c ^
U.S. DEPARTMENT OF COMMERCE
National Technical Information Service
PB-252 864
Handbook for
Pesticide Disposal by
Common Chemical Methods
TRW Systems Group
Prepared For
Environmental Protection Agency
December 1975
J
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HANDBOOK FOR PESTICIDE DISPOSAL
BY COMMON CHEMICAL METHODS
This study (SW-112o) describes work performed
for the Federal solid waste management programs under contract No. 68-01-2956
and is reproduced as received from the contractor
U.S. ENVIRONMENTAL PROTECTION AGENCY
1976
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sheet | EPA/530/SW-11?c 1
pt- ~1V4'
4. Title and Subtitle
Handbook for Pesticide Disposal by Camion Chemical Methods
5. Report Date
December, 1975
6.
7. Author(s)
C.C. Shih and D.F. Dal Porto
8. Performing Organization Rept.
No.
9. Performing Ofgfltllfcation Name and Address
TRW Systems, Inc.
One Space Park
JRedondo Beach, CA 90278
10. btaOSKt/Task/VJBfcdtHjKNo.
68-01-3207
11. Contract No.
68-01-2956
12. Sponsoring Organization Name and Address
Office of Solid Waste Management Programs, U.S. Environmental
Protection Agency, Washington, DC 20460
13. Type of Report & Period
Covered
14.
15. Supplementary Notes
16. Abstracts ij^g study is concerned with utilizing chemical degradatioVdetoxification
methods for the disposal of small quantities of pesticide wastes. A primary objective
of the study is to develop procedures to advise pesticide users of safe, readily
available chemical methods for pesticide disposal. Another objective is to delineate
the hazards associated with pesticide disposal by chemical methods, and warn the
layman against the indiscriminate use of chemical disposal methods based on incomplete
knowledge of the degradation products or the hazardous nature of the detoxifying
reagents. Chemical degradation information on twenty different pesticides, represent-
ing each of the major pesticide classes, is discussed. Chemical degradation procedures
that can be used by the laymen are described for naled, diazinon, Guthion, malathion,
carbaryl, captan, and atrazine, but not for Dursban, methyl parathion, maneb, alachlor
(Lasso), diuron, picloram, trifluralin, methoxychlor, chlordane, toxaphene, 2,4-D,
amiben (chloramben), and pentachlorophenol.
17. Key Words and Document Analysis. 17a. Descriptors
Pesticide, degradation, detoxification, disposal
17b. identifiers /Open-Ended Terms
Chemical disposal, chemical detoxification, pesticide disposal
17c. C0SAT1 Field/Group
19.. Security Class (This
Report)
IjqClASSIFIF.n
20. Security Class (This
Page
UNCLASSIFIED
| 21. No, of Pages
FORM NTIS-35 (REV. 3-721
USCOMM-DC 14952-P72
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This report has been reviewed by the U.S. Environmental Protection
Agency and approved for publication. Approval does not signify that the
contents necessarily reflect the views and policies of the U.S. Environmental
Protection Agency, nor does mention of ccnraercial products constitute
endorsement or recommendation for use by the U.S. Government.
The recommended detoxification procedures contained in this report are
based on information that is believed to be reliable and best efforts
have been made to confirm the information obtained. However, no warranty
or guarantee is made concerning the accuracy or sufficiency of any Infor-
mation, and TRW does not assume any responsibility in connection with any
accidents or injuries which may result from using the detoxification
procedures prescribed in this report.
ii
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ACKNCWLEDGEMEOT
This project is deeply indebted to the EPA Project Officer,
Mr. Harry W. Trask, for his continuing advice and guidance during the
course of the study. Thanks are also due to other staff members of the
Office of Solid Waste Management Programs for their critical review of
the draft final report.
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ABSTRACT
The present study is concerned with examining the practicability of
utilizing chemical degradation/detoxification methods for the disposal Of
small quantities of pesticide wastes. The objectives of the study are
twofold: (i) to develop procedures to advise pesticide users of safe and
readily available chemical methods for pesticide disposal; and (ii) to
delineate the hazards associated with pesticide disposal by common chenii-
cal methods. A total of twenty pesticides representative of the major
pesticide classes were investigated. Based on a review of the literature
on pesticide chemistry and information provided by the pesticide manufac-
turers, it was determined that treatment with alkali is an effective and
environmentally safe method for the disposal of small quantities of naled,
diazinon, Guthion, malathion, carbaryl, captan, and atrazine. For these
seven pesticides, detailed disposal procedures were developed to give
directions on the quantities and concentrations of caustic soda and addi-
tives to be used, the contact time required to complete the degradation
process, and the methods for handling reaction product mixtures and rinse
solutions. The review and analysis of the information collected also
indicate no practical chemical degradation/detoxification methods exist
for the disposal of Dursban, methyl parathion, maneb, alachlor (Lasso),
diuron, picloram, trifluralin, methoxychlor, chlordane, toxaphene, 2,4-D,
amiben (chloramben), and pentachlorophenol.
iv
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TABLE OF CONTENTS
Page
SUMMARY 1
1. INTRODUCTION 5
2. CLASSIFICATION AND SELECTION OF PESTICIDES 9
2.1 CLASSIFICATION OF PESTICIDES 9
2.2 PRIORITIZATION SYSTEM FOR PESTICIDE SELECTION 10
2.3 SELECTION OF CANDIDATE PESTICIDES 15
3. RECOMMENDED PROCEDURE FOR THE DISPOSAL OF SELECTED
PESTICIDES 23
4. CONCLUSIONS AND RECOMMENDATIONS 33
APPENDIX A CHEMICAL METHODS FOR THE DEGRADATION/DETOXIFICATION OF
PHOSPHORUS-CONTAINING PESTICIDES 43
A.1 GENERAL REVIEW OF APPLICABLE DISPOSAL METHODS. . . 45
A.2 CHEMICAL METHODS FOR THE DEGRADATION/DETOXIFICATION
OF NALED 49
A.3 CHEMICAL METHODS FOR THE DEGRADATION/DETOXIFICATION
OF DIAZINON 51
A.4 CHEMICAL METHODS FOR THE DEGRADATION/DETOXIFICATION
OF DURSBAN 56
A.5 CHEMICAL METHODS FOR THE DEGRADATION/DETOXIFICATION
OF METHYL PARATHION 58
A.6 CHEMICAL METHODS FOR THE DEGRADATION/DETOXIFICATION
OF GUTHION 61
A.7 CHEMICAL METHODS FOR THE DEGRADATION/DETOXIFICATION
OF MALATHION 64
APPENDIX B CHEMICAL METHODS FOR THE DEGRADATION/DETOXIFICATION OF
NITROGEN-CONTAINING PESTICIDES 67
B.l GENERAL REVIEW OF APPLICABLE DISPOSAL METHODS. . . 69
B.2 CHEMICAL METHODS FOR THE DEGRADATION/DETOXIFICATION
OF CARBARYL 69
B.3 CHEMICAL METHODS FOR THE DEGRADATION/DETOXIFICATION
OF MANEB 73
v .
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TABLE OF CONTENTS
(CONTINUED)
Page
B.4 CHEMICAL METHODS FOR THE DEGRADATION/DETOXIFICATION
OF ALACHLOR 75
B.5 CHEMICAL METHODS FOR THE DEGRADATION/DETOXIFICATION
OF CAPTAN 77
B.6 CHEMICAL METHODS FOR THE DEGRADATION/DETOXIFICATION
OF DIURON . . 78
B.7 CHEMICAL METHODS FOR THE DEGRADATION/DETOXIFICATION
OF ATRAZINE 79
B.8 CHEMICAL METHODS FOR THE DEGRADATION/DETOXIFICATION
OF PICLORAM 82
B.9 CHEMICAL METHODS FOR THE DEGRADATION/DETOXIFICATION
OF TRIFLURALIN 84
APPENDIX C CHEMICAL METHODS FOR THE DEGRADATION/DETOXIFICATION OF
HALOGEN-CONTAINING PESTICIDES 87
C.l GENERAL REVIEW OF APPLICABLE DISPOSAL METHODS ... 89
C.2 CHEMICAL METHODS FOR THE DEGRADATION/DETOXIFICATION
OF METHOXYCHLOR 89
C.3 CHEMICAL METHODS FOR THE DEGRADATION/DETOXIFICATION
OF CHLORDANE. 90
C.4 CHEMICAL METHODS FOR THE DEGRADATION/DETOXIFICATION
OF TOXAPHENE 91
C.5 CHEMICAL METHODS FOR THE DEGRADATION/DETOXIFICATION
OF 2,4-D 93
C.6 CHEMICAL METHODS FOR THE DEGRADATION/DETOXIFICATION
OF AMI BEN 96
C.7 CHEMICAL METHODS FOR THE DEGRADATION/DETOXIFICATION
OF PENTACHLOROPHENOL. 97
APPENDIX D NACA TRIPLE RINSE AND DRAIN PROCEDURE 99
REFERENCES 103
vi
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SUMMARY
This study is concerned with examining the practicability of utilizing
chemical degradation/detoxification methods for the disposal of small quan-
tities of pesticides wastes. A primary objective of the study is to develop
procedures to advise pesticide users of safe, readily available chemical
methods for pesticide disposal. A second objective, of equal importance,
is to delineate the hazards associated with pesticide disposal by chemical
methods, and to warn the laymen against the indiscriminate use of chemical
disposal methods based on incomplete knowledge of the degradation products
or the hazardous nature of the detoxifying reagents.
The approach was to conduct an in-depth investigation on twenty key
pesticides representative of each major pesticide class, rather than attempt
to cover all commercially available pesticides. The pesticides were classi-
fied into chemical families. The principal criteria used in selecting the
representative pesticides from each chemical class were production volume
and toxicity. Secondary considerations in the selection of the pesticides
included the representativeness of the chemical structure of the pesticide
within the chemical class, persistence in the soil, mobility, and solubility
in water. The twenty pesticides selected for the TRW study were:
Phosphorus-containing pesticides - naled, diazinon, Dursban
(chlorpyrifos), methyl parathion, Guthion (azinphosmethyl),
and malathion.
Nitrogen-containing pesticides - carbaryl (Sevin), maneb,
alachlor (Lasso), captan, diuron, atrazine, picloram, and
trifluralin.
Chlorine-containing pesticides - methoxychlor, chlordane,
toxaphene, 2,4-D, amiben (chloramben), and pentachlorophenol.
Identification of practical chemical degradation/detoxification methods
for pesticide disposal was accomplished by a review of the literature on
pesticide chemistry. In addition, the manufacturers were directly contacted
for readily available information and published instructions. The emphasis
was on simple chemical disposal methods suitable for use by laymen.
-------
From the results of the review, it was determined that treatment with
alkali is an effective and environmentally safe method for the disposal of
small quantities of naled, diazinon, Guthion, malathion, carbaryl, captan
and atrazlne. This conclusion was reached after careful assessment of the
completeness of the degradation process and the identity and toxicity of
the degradation products. The disposal procedures presented in this report
give directions on the quantities and concentrations of caustic soda and
additives to be used, The contact time required to complete the degrada-
tion process, and methods for handling reaction product mixtures and rinse
solutions.
Equally important, the review and analysis of the information collected
also indicate no practical chemical degradation/detoxification methods
exist for the disposal of Dursban, methyl parathion, maneb, alachlor (Lasso),
diuron, picloram, trifluralin, methoxychlor, chlordane, toxaphene, 2,4-D,
amiben (chloramben), and pentachlorophenol. Chemical methods are not rec-
ommended for one or more of the following reasons:
The extent of chemical degradation is unknown or incomplete.
The identify of the degradation products are unknown,
The environmental hazards of the degradation products are
unknown.
§ The chemical reagents involved are expensive and hazardous.
The chemical degradation products are hazardous.
Of particular concern is the hazardous nature of the pesticide degradation
products not often recognized by laymen. For example, the degradation
products from the acid or alkaline hydrolysis of methyl parathion, maneb,
alachlor, and diuron are either toxic or may lead to the formation of
suspected carcinogens.
Overall, chemical detoxification can be an effective method for the
disposal of small quantities of certain pesticide wastes. At the same
time, it should be noted that the applicability of a chemical treatment
method to pesticide disposal must be evaluated in terms of each specific
pesticide. The reaction chemistry between the pesticide requiring dis-
posal and the chemical decontaminant used, as well as the environmental
2
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hazards of the degradation products, must be sufficiently understood
before a chemical detoxification procedure is employed. The final recom-
mendations on the twenty pesticides investigated are summarized in Table 1.
TABLE 1
CHEMICAL DISPOSAL OF PESTICIDES
Do
Don't
Use alkali:
Use chemical treatment:
Naled
Dursban
Diazinon
Methyl Parathion
Guthion
Maneb
Malathion
Alachlor (Lasso)
Carbaryl
Diuron
Captan
Picloram
Atrazine
Tri fluralin
Precautions:
Metho*ychlor
Chlordane
Use personal protection equipment.
Toxaphene
Follow disposal procedure closely.
2,4-D
Dispose larger quantities in
Ami ben
several smaller batches.
Pentachlorophenol
3
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1. INTRODUCTION
The improper disposal of surplus pesticides and used pesticide
containers is a problem that poses a threat to both man and the environ-
ment. The normal recommended disposal methods, principally incineration
or burial in specially designated landfills, have not been practiced by
a majority of the end users of pesticides due to the scarcity of available
facilities. For a number of pesticides, chemical degradation/detoxification
offers the best alternative as an environmentally acceptable method for the
disposal of small quantities of pesticides. Like incineration, the degra-
dation products of the chemical treatment of pesticides can be predicated
and controlled by the selection of appropriate chemical reagents and reac-
tion conditions. The adequacy of a chemical treatment method can be deter-
mined from the knowledge of the extent of degradation, and the identity and
environmental hazards of the degradation products.
The present study is aimed at the gathering of information necessary
for the development of procedures to advise pesticide users of safe, readily
available chemical methods for pesticide disposal. Another purpose is to
provide pesticide users with a tool that will permit them to evaluate the
feasibility of utilizing chemical degradation procedures contained in labels
or labeling of pesticide products. Equally important, this study will warn
the laymen of the hazards associated with the chemical degradation of many
pesticides, including the hazardous nature of the end products as well as
the operating hazards. To accomplish these objectives, the TRW program was
organized into the following project elements:
a. Selection of 20 representative pesticides;
b. Identification of practical chemical degradation/detoxification
methods for pesticide disposal;
c. Development of pesticide disposal procedures.
The 20 pesticides investigated were selected to represent each major
pesticide class from the multiplicity of pesticidal compounds which cover
a wide range of chemical structures. The principal criteria used in
Preceding page blank
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selecting the representative pesticides from each chemical class were the
production volume and toxicity, and a prioritization model was utilized to
quantify the combined effects of these two factors. Secondary considera-
tions in the selection of the pesticides included the representativeness
of the chemical structure of the pesticide within the chemical class,
persistence in the soil, mobility, and solubility in water. The 20 pesti-
cides selected for the TRW study were:
Phosphorus-containing pesticides - naled, diazinon, Dursban
(chlorpyrifos), methyl parathion, Guthion (azinphosmethyl),
and malath ion.
Nitrogen-containing pesticides - carbaryl (Sevin), maneb,
alachlor (Lasso), captan, diuron, atrazine, picloram, and
trifluralin.
Chlorine-containing pesticides - methoxychlor, chlordane,
toxaphene, 2,4-D, amiben (chloramben), and pentachlorophenol.
The identification of practical chemical degradation/detoxification
methods for pesticide disposal was accomplished by an extensive review of
the literature on pesticide chemistry. In addition, the manufacturers of
the selected pesticides were directly contacted for readily available infor-
mation and published instructions on methods of chemical detoxification.
The emphasis was on simple chemical disposal methods suitable for use by
laymen, such as alkaline hydrolysis and chemical oxidation by sodium
hypochlorite treatment. Equal importance was also placed on the identifi-
cation of pesticides that should not be treated by the common chemical
methods, as a result of incomplete knowledge of the degradation products
or the generation of degradation products that were equally or more toxic
than the starting material.
The information collected on the most practical and reliable methods
for the chemical degradation/detoxification of the selected pesticides was
utilized to develop disposal procedures which give directions on the quanti-
ties and concentrations of the reagents and additives to be used, as well
as the handling of the reaction product mixtures and rinse solutions. The
6
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final recommended procedures are based on the recommendations of the
pesticide manufacturers and the National Agricultural Chemicals Associa-
tion together with information from the literature, taking into account
the considerations that the detoxifying reagents used should be relatively
common and low in cost, easy to handle, and pose no significant hazard to
man and the environment. For the pesticides for which chemical degradation/
detoxification techniques were not applicable, alternate methods for the
disposal of small quantities of these pesticides have been suggested. The
incorporation of the input from the pesticide manufacturers into the final
recommendations, as well as the approach to concentrate on a selected number
of key pesticides, are the major differences between the present TRW study
and similar types of studies on the chemical degradation of pesticides.
The main body of this report is divided into four sections, the first
of which is this introduction. Section 2 describes the selection of the
representative pesticides for this study. In Section 3, the recommended
procedures for the disposal of small quantities of pesticides and the decon-
tamination of pesticide containers are presented. The conclusions and
recommendations that have resulted from the TRW investigation are summarized
in Section 4. The detailed review and discussion of the chemical methods
available for the degradation/detoxification of the phosphorus, nitrogen,
and chlorine containing pesticides are presented in Appendices A, B and C,
respectively. The triple rinse and drain procedure for pesticide containers
developed by the National Agricultural Chemicals Association is included in
Appendix D of this report.
7
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2. CLASSIFICATION AND SELECTION OF PESTICIDES
Over several hundred insecticides, herbicides and fungicides are pre-
sently being sold in the United States and consequently, a complete study
to determine the recommended chemical degradation/detoxification methods
for all or a majority of these pesticides would be a major effort and
outside the scope of this program. Therefore, the approach utilized
in this program was to select an appropriate number of key pesticides
representative of each major pesticide class.
2.1 CLASSIFICATION OF PESTICIDES
For the present study, the classification of pesticides into chemical
families of compounds is more relevant than the classification according to
use patterns or applied characteristics, and the pesticide classification
system suggested by the Midwest Research Institute (MRI) in the "Guidelines
for the Disposal of Small Quantities of Unused Pesticides" report, with minor
modifications, is most applicable. The MRI system classifies the pesticides
into seven major categories:
Inorganic and metallo-organic pesticides
Phosphorus-containing pesticides
Nitrogen-containing pesticides
Halogen-containing pesticides
Sulfur-containing pesticides
Botanical and microbiological pesticides
Organic pesticides, not elsewhere classified
The predominant inorganic and metallo-organic pesticides are compounds
containing either arsenic, mercury or copper, and the fundamental toxic
character of these metals or elements cannot be destroyed by any chemical
Preceding page blank 9
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method. The inorganic and metallo-organic pesticides were therefore not
considered in this study. The sulfur-containing pesticides do not pose
serious toxicity or environmental hazards and as with the botanical and
microbiological pesticides, are not produced in significant quantities.
For these reasons, it is more appropriate to classify the pesticides which
might utilize chemical detoxification into four major categories:
0 Phosphorus-containing pesticides
Nitrogen-containing pesticides
Halogen-containing pesticides
Miscellaneous pesticides
It should be noted that according to.this pesticide classification system,
a pesticide that contains phosphorus, nitrogen, halogen and other elements
is normally classified as a phosphorus compound. The usefulness of this
method of classification is supported by the fact that the decomposition
chemistry of a pesticide containing phosphorus and other elements will most
likely depend primarily on the chemistry of the phosphorus-containing por-
tion of the. molecule.
To ensure the proper selection of representative pesticides, the fur-
ther classification of pesticides within each major category is necessary.
Again, the MRI system for subclassification, with a number of modifications
and combinations, is used. The revised pesticide classification system is
presented in Table 2, together with examples of typical pesticides in each
pesticide class.
2.2 PRIORITIZATION SYSTEM FOR PESTICIDE SELECTION
The criteria used in the selection of representative pesticides from
each chemical class included: the quantity of the pesticide requiring dis-
posal, its hazard to the environment, and the representativeness of the
chemical structure of the pesticide within the chemical class. To provide
for a quantitative basis of the selection process, a simple model was developed
for prioritizing the pesticides within each chemical subclass. In the
10
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TABLE 2
PESTICIDE CLASSIFICATION SYSTEM
Pesticide Class
Typical Pesticides
in Each Chemical Class
I. Phosphorus-Containing Pesticides
(i) Phosphates and Phosphonates
(ii) Phosphorothioates
(iii) Phosphorodithioates
(iv) Other Organophosphates
Mevinphos, TEPP, Azodrin, Dichlorvos,
Bidrin, Naled
Diazinon, Methyl Parathion, Parathion,
Demeton, Dursban, Fenthion, Zinophos,
Dasanit
Disulfoton, Phorate,Malathion, Guthion,
Ethion, Trithion
Ruelene, DEF Defoliant, Folex
II. Nitrogen-Containing Pesticides
(i) Carbamates, Thiocarbamates and
Oithiocarbamates
(ii) Amides, Anil ides, Imides, and
Hydrazides
(i 1 i) Ureas and UraciIs
(iv) Triazines
(v) Amines, Nitro Compounds, and
Quaternary Ammonium Compounds
(vi) Other Nitrogen-Containing Compounds
Carbaryl, Aldicarb, Carbofuran, Bux Ten,
Sutan, Eptam, Maneb, Ferbam, Zineb
Diphenamid, Alachlor, Randox, Propachlor,
Captan, Difolatan, MH
Diuron, Linuron, Monuron, Bromacial
Atrazine, Propazine, Simazine
Picloram, Trifluralin, Benefin, Nitralin,
Dinoseb, Diquat, Paraquat
Antu, Dodine, Naptalam
III. Halogen-Containing Pesticides
(i) DDT and Related Compounds
(ii) Chlorophenoxy Compounds
(iii) Aldrin-Toxaphene Group
(iv) Dihaloaromatic Compounds
(v) Highly Halogenated Compounds
Methoxychlor, Chlorobenzilate, Dicofol
2,4-D,Silvex, 2,4,5-T, MCPA
Chlordane, Toxaphene, Endrin, Heptachlor
Amiben, Paradichlorobenzene, Banvel
Pent^chlorophenol, Fenac, Dacthal
IV. Miscellaneous Pesticides
Warfarin, Endothall, Fumarin, Rotenone,
Pyrethins, Sodium Fluoroacetate, Omite
11
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development of the priority ranking model, the pesticide waste quantity
factor was considered to be of equal importance as the environmental hazard
factor in establishing priorities; i.e., a highly toxic or hazardous
pesticide waste generated in relatively small quantities was considered
equally damaging as a moderately toxic or hazardous pesticide waste gen-
erated in relatively large quantities. The simplest mathematical relation-
ship that expresses this type of priority ranking for hazard and quantity
factors r^ and Q respectively, is the product function:
PR = r .Q
where PR is the numerical ranking factor. Since the quantity of the pesti-
cide requiring disposal is directly related to the production volume,* the
quantity factor Q was assigned with values related to the annual production
volume of each pesticide as follows:
Annual Production Volume of Pesticide 3.
>45,400 metric tons (100 million lb) per year 1000
4540 to 45,400 metric tons (10 to 100 million lb) per year 100
454 to 4540 metric tons (1 to 10 million lb) per year 10
<454 metric tons (1 million lb) per year 1
The hazard rating factor rf was more difficult to define, since a
pesticide may be classified as hazardous by virtue of any number of factors.
It may present an oral, dermal, or inhalation toxicity hazard. It may be
toxic to aquatic life if leachate from the soil reaches surface waters. It
may be subject to bi©concentration, or represent a carcinogenic, mutagenic,
or teratogenic hazard. In addition, all these hazard factors may be magni-
fied by the persistence of the pesticide in soil, or its mobility and
solubility in water.
~
Except in the case of DDT, where all domestic production is for export.
12
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In general, there will be more than one reason to rate a pesticide as
hazardous. The National Academy of Sciences - National Research Council* (NAS
NRC), faced with a similar problem in evaluating potential hazards of indus-
trial chemicals, concluded that it was only possible to rank with respect to
each particular phase of the total hazard, considered by itself. It was
also noted that any attempt to use mathematical operations to produce an
index or composite in the form of one number should be discouraged, since
such oversimplification can produce confusion and misunderstanding.
For the purposes of this program, the hazard factor, r^, was calcu-
lated on the basis of the "worst" potential hazard presented by the
pesticide. Numerical values of rf were assigned with reference to Table 3,
which was derived from the NAS-NRC Report: "System for Evaluation of the
Hazards of Bulk Water Transportation of Industrial Chemicals", with the
2
appropriate modifications. The flammability and reactivity hazards have
both been eliminated from the rating system, as these are not hazards gen-
erally associated with pesticides. Also, in the NAS-NRC report, four hazard
"grades" are defined, ranging from slightly hazardous to extremely hazardous.
In Table 2, r values of 1, 10, 100 or 1000 have been arbitrarily assigned
to NAS-NRC Grades 1, 2, 3 and 4 respectively, and rf is taken as the highest
value of r exhibited by the pesticide in any hazard category. According to
the proposed hazard rating system, a pesticide such as DDT which is known to
bioaccumulate in the food chain, has a 48-hour TLm of 0.0021 mg/1 for fish
and a moderate acute oral toxicity, is assigned the highest hazard rating of
1000 because of either its bioaccumulative property or its extreme hazard
to aquatic life.
It may be noted that the hazard rating system does not include either
mobility or persistence in the soil among its hazard categories. Mobility
or persistence in the soil is not a hazard in itself and only serves to
increase the degree of a hazard already present. The mobility of a pesti-
cide depends on the physico-chemical properties of the pesticide as well as
the soil and must take into account such factors as formulation type,
solubility, ionic charge of the pesticide and the moisture content, tem-
perature, pH and organic matter and clay contents of the soil. Mobility
13
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TABLE 3
HAZARD RATING SYSTEM
Hazard Rating (r)
Hazard Category
1000
100
10
1
1. Bioaccumulation
Bioaccumulated and liable
to produce a hazard to
aquatic life or human
health
Not known to be significantly
bioaccumulated
2. Oral Toxicity
LD50 < 5 mg/kg
LD^q 5-50 mg/kg
LD^q 50-500 mg/kg
LDjq 500-5000 mg/kg
! 3. Inhalation
Toxicity
LC5q < 50 ppm or
< 0.5 mg/1 or
or 0SHA 1 ppm
LCgg 50-200 ppm or
0.5-2mg/l or OSHA
1-10 ppm
LC50 200-2000 ppm
or OSHA 10-100 ppm
OSHA 100-1000 ppm
4. Dermal Toxicity
LDgg < 20 mg/kg
24 hour skin contact
LDg0 20-200 mg/kg
24 Hour skin contact
Corrosive to skin
Lachrymators
5. Aquatic Toxicity
TLm <1 mg/1
TLm 1-10 mg/1
TLm 10-100 mg/1
TL 100-1000 mg/1
m J
6. Teratogenicity
Known to be teratogenic
Not known to be teratogenic
7. Carcinogenicity
Known to be carcinogenic
Not known to be carcinogenic
8. Mutagenicity
Known to be mutagenic
Not known to be mutagenic
r^ is the highest value of r exhibited by the pesticide in any hazard category.
-------
data, based on soil thin-layer chromatography, are only available for the
most common soil-applied pesticides. The pesticide mobility factor was
therefore only a secondary consideration in the selection of the candi-
date pesticides. The persistence of a pesticide in soil depends to a large
extent on its chemical classification. For example, organochlorine in-
secticides are the most persistent pesticides (from 1 to 5 years), whereas
the organophosphate insecticides do not persist for long periods in most
soils (less than 3 months). Since the candidate pesticides were selected
to represent each chemical class listed in Table 2 and pesticides of the
same chemical class normally persist in soil for similar periods of time,
the persistence factor was again only a secondary consideration in the
selection process.
Although both Q and rf may assume values of 1, 10, 100 or 1000, there
are no pesticides produced at over 45,400 metric tons (100 million lb) per
year and hence the highest Q value possible is 100 and the product PR can
range from 1 to 105 in multiples of 10. For convenience, the discussion
on the selection of the candidate pesticides will refer to log PR rather
than PR. Thus a log PR rating of 5 is the highest priority ranking and a
log PR rating of 1 is the lowest priority ranking in the selection process.
2.3 SELECTION OF CANDIDATE PESTICIDES
The selection of the candidate pesticides is discussed with reference
to the chemical classification system presented in Table 2.
Phosphorus-Contai ning Pesti ci des
(i) Phosphates and Phosphonates. Naled was the only pesticide assigned
with the top log PR rating of 4 for this group and was selected.
(ii) Phosphorothioates. This is one of the most important chemical sub-
class of pesticides. Two pesticides were assigned the highest possible log
15
-------
PR rating of 5 in this group - diazinon and parathion. Four other pesti-
cides in this group were assigned the high log PR rating of 4 - chloropyntfos
(Dursban), dasanit, methyl parathion, and ronnell. Methyl parathion was
selected over parathion to represent this group because it is one of the
largest volume insecticide produced and parathion is being displaced more
and more by methyl parathion. In addition, diazinon and Dursban were
selected.
(iii) Phosphorodithioates. Malathion was assigned the highest possible
log PR rating of 5 in this group and was selected. Five other pesticides
in this group were assigned the high log PR rating of 4 - azinphosmethyl
(Guthion), carbophenothion (Trithion), disulfoton (Di-Syston), ethion, and
phorate (Thimet). Azinphosmethyl is the only heterocyclic derivative of
dithiophosphoric acid with a high log PR rating of 4 and was selected. The
heterocyclic derivatives of dithiophosphoric acid have a strong insecticidal
effect not only on suckling plant pests, but also on various leaf-eating
insects. In many cases these compounds are very promising as substitutes
for the chlorine-containing insecticides such as DDT and have attracted
increasing attention.
(iv) Other Orqanophosphates. The only pesticide from this group assigned
a log PR rating of 4 was the DEF-defoliant. The DEF defoliant is only
moderately toxic to animals, and its high priority rating was due to its
aquatic toxicity - a 48-hour TLm of 0.036 mg/1 for fish. Since six pesti-
cides have already been selected to represent the three most important
chemical subclass of phosphorus-containing pesticides, no pesticide from
this rather inhomogeneous group was selected.
Nitrogen-Containing Pesticides
(i) Carbamates, Thiocarbamates and Dithiocarbamates. Carbaryl (Sevin) and
aldicarb (Temik) were the two pesticides assigned the log PR rating of 4
for the carbamates. Carbaryl was selected over aldicarb to represent the
carbamates because of its much larger production volume. In addition, the
salts of substituted dithiocarbamic acids, and especially the salts of
16
-------
ethylenebis (dithiocarbamic) acid, are the most widely used fungicides
employed for the protection of growing plants. Maneb was selected to
represent the dithiocarbamates because the production of other fungicides
in this group such as nabam and zineb are gradually being reduced.
(ii) Amides, Anil ides, Imides and Hydrazides. Captan was the only pesti-
cide in this group assigned with a log PR rating of 5 and was therefore
selected. Difolatan was assigned a log PR rating of 4 but belongs to the
imide group already represented by the higher priority captan. Three
other pesticides in this group were assigned with a log PR rating of 2 -
alachlor (Lasso), CDAA (Randox), and propachlor (Ramrod). All three are
volume herbicides and fungicides of moderate hazard produced at over 4,540
metric tons (10 million lb) per year. Alachlor was selected as the second
representative pesticide from this group because its production volume was
twice that of CDAA (9080 metric tons vs 4540 metric tons in 1972), and it
has a longer residual action in soil than propachlor (ten to twelve weeks
versus four to six weeks).
(iii) Ureas and Uracils. Diuron was the only pesticide from this group
assigned with a log PR rating of 3 and was therefore selected. Diuron is
also persistent and slightly mobile in soil.
(iv) Triazines. Atrazine, Dyrene, propazine and simazine were all assigned
with a log PR rating of 3. Atrazine was selected over the three other pesti-
cides to represent this group because it is produced in much larger quantities.
(v) Amines, Nitro Compounds, and Quaternary Ammonium Compounds. Triflur-
alin was assigned with the highest log PR rating of 5 because of its aquatic
toxicity and large production volume. Trifluralin was selected to represent
the nitro compounds. In addition, picloram, which was assigned with a log
PR rating of 3, was selected to represent the amine compounds. Picloram is
persistent in soil, mobile, and water-soluble, and small amounts of this
herbicide irrigated on sensitive crops could lead to disastrous results.
(vi) Other Nitrogen-Containing Pesticides. There are no major pesticides
included in this group and none was selected.
17
-------
Halogen-Containing Pesticides
(i) DPT and Related Compounds. Methoxychlor was assigned with the log PR
rating of 5 and was selected to represent this group.
(ii) Chlorophenoxy Compounds. 2,4-D was the only pesticide in this group
assigned with the log PR rating of 5 and was selected.
(iii) Aldrin-Toxaphene Group. Both chlordane and toxaphene were assigned
with the log PR rating of 5 and were selected.
(iv) Dihaloaromatic Compounds. Chloramben (amiben) and paradichlorobenzene
were both large volume pesticides (over 9,000 metric tons per year) assigned
with a log PR rating of 2. Dichlone was assigned with a higher log PR
rating of 3, but its production volume is unknown and presumably much less
than 454 metric tons (1 million lb) per year. Also, paradichlorobenzene is
generally formulated as the 100 percent crystals, popular for domestic use
against clothes moths and does not present a significant disposal problem.
Chloramben was therefore selected to represent this group.
(v) Highly Halogenated Compounds. Pentachlorophenol was the only pesti-
cide in this group assigned with a high log PR rating of 5 and was selected.
Miscellaneous Pesticides
Warfarin is the only pesticide in this group produced in significant
quantities and is not suitable for disposal by chemical methods. None of
the pesticides in this group can be considered as representative and none
was selected.
The list of the candidate pesticides selected for the present study
is presented in Table 4. In Table 5, the production volume and the hazard
properties of the selected pesticides are summarized. It may be noted that
the list of candidate pesticides includes all the pesticides with an annual
production volume of over 4,540 metric tons (10 million lbs), with the
18
-------
TABLE 4
LIST OF SELECTED PESTICIDES
Pesticide Class
Candidate Pesticides
I.
Phosphorus-Contai n1ng Pesti cldes
(i)
Phosphates and Phosphonates
Naled
(11)
Phosphorothloates
Diazinon, Methyl Parathion, Dursban
(ill)
PhosphoroditMoates
Guthlon, Malathion
II.
Nitrogen-Containing Pesticides
(1)
Carbamates, Thiocarbamates, and
Dithiocarbamates
Carbaryl, Maneb
(ii)
Amides, Anilides, Imides, and
Hydrazldes
Alachlor, Captan
(Hi)
Ureas and Uracils
Dluron
(iv)
Triazines
Atrazlne
(v)
Amines, Nitro Compounds,
Quaternary Ammonium
Compounds
Plcloram, Trifluralin
III.
Halogen-Containing Pesticides
(D
DDT and Related Compounds
Methoxychlor
(11)
Chlorophenoxy Compounds
2,4-D
(111)
Aldrin-Toxaphene Group
Chlordane, Toxaphene
(iv)
Dihaloaromatic Compounds
Ami ben
(v)
Highly Halogenated Compounds
Pentachlorophenol
19
-------
TABLE 5
PRODUCTION VOLUME AND HAZARD PROPERTIES OF THE SELECTED PESTICIDES*
Production
H*7ar<1s+
Persistence
Pesticide
Volus*
(Metric Tons
Per Year)
Producti on
Ratina
Q
Acute
Oral LDjo
(mg/kg)
Acute
Dermal 10H
(ng/fcg)
48-hour
,Tt* ,
(mg/1)
Other
Hazards
Hazard
Rating
ff
log
CO.rf)
in
Soil
(Months)
Mobi1i ty
Water Solubility*
Naled
910
10
430
800
0.078
1,000
4
Insoluble
Oiazinon
4,540
100
300-850
>2,150
0.03
--
1,000
5
3-12
Slightly mobile
40 ppm
Methyl Parathion
20,430
100
14-24
67
8
--
100
4
1-3
Slightly mobile
55 ppm
Dursban
2,270
10
135
2,000
0.02
--
1,000
4
1-3
--
2 ppm
Guthion
1,820
10
16
220
0.01
-
1,000
4
--
Slightly mobile
33 ppm
Kalathion
13,620
100
2,800
4,100
0.02
-
1,000
5
1-3
--
145 ppm
Carhary 1
20,430
100
850
4,000
1.5
--
100.
4
1-3
--
40 ppm at 30°C
Maneb
454-4,540
10
6,750
>1,000
1-10
-
100
3
-
--
Slightly mobile
Alachlor
9,080
100
1,200
>2,000
--
--
1
2
--
-
40 ppm
Captan
39,600
100
9,000
--
0.3
--
1,000
5
--
--
<0.5 ppm
Oiuron
2,720
10
3,400
--
4.3
-
100
3
>12
Slightly mobile
42 ppm
Atrazine
40,860
100
3,080
..
12.6
--
10
3
>12
Slightly mobile
33 ppm
Picloram
1,360
10
8,200
>4,000
2.5
--
100
3
>12
Mobile
430 ppm
Trifluralin
11,350
100
>10,000
>5,000
0.011
--
1,000
5
3-12
lomobile
<1 ppm
Methoxychlor
4,540
100
6,000
0.007
--
1,000
5
--
-
Insoluble
2,4-0
20,430
100
375-805
0.8-2.1
--
1,000
s
1-3
Mobile
620 ppm
Chlordane
11,350
100
457-590
690
0.01
--
1,000
5
>12
Immobile
Insoluble
Toxaphene
22,700
100
80-90
1,075
0.003
--
1,000
5
--
Iomobile
Insoluble
Aim ben
9,080
100
5,620
>3,160
--
-
1
z
1-3
--
700 ppm
Pentach 1 a rophenol
20,880
10
25-200
150-350
0.2
--
1,000
5
--
--
20 ppm at 30'C
*Preduction volume data are 1972 figures obtained from Reference 1. The oral and dermal hazard data were obtained from References 3 and 4. The aquatic
toxicity data were obtained from References 5, 6 and 7. The data on persistence in soil, mobility and water solubility were obtained from References 3, 8
and 9.
-The acute oral and dermal LD^g values are for rats. The 58-hour TLm values are for fish.
'water solubility data are at 25°C, unless otherwise specified. Also, note that the potassium salt of picloram, the sodium salt of pentachlorophenol,
and the amine salt of 2,4-0 are very soluble in water.
-------
exception of propachlor, CDAA, parathlon, methyl bromide, the arsenic-
containing organic pesticides and the inorganic pesticides. As discussed
previously, both propachlor and CDAA are similar in chemical structure to
alachlor, which has been selected, also, parathion is similar in chemical
structure to the selected methyl parathion. Methyl bromide is usually
stored in returnable pressurized containers and does not present a signif-
icant disposal problem. The arsenic-containing organic pesticides and the
inorganic pesticides are generally not suitable for treatment by chemical
degradation/detoxification methods.
21
-------
3. RECOMMENDED PROCEDURE FOR THE
DISPOSAL OF SELECTED PESTICIDES
The identification of practical chemical degradation/detoxification
methods for pesticide disposal was accomplished by an extensive review of
the literature on pesticide chemistry. In addition, the manufacturers of
the selected pesticides were directly contacted for readily available
information and published instructions on methods of chemical detoxification.
The detailed review and discussion of the chemical methods available for
the degradation/detoxification of the phosphorus, nitrogen and chlorine
containing pesticides are presented in Appendices A, B, and C of this
report. From the results of analysis of the information collected, it
was determined that treatment with alkali is an effective and environ-
mentally safe method for the disposal of small quantities of naled, diazinon,
Guthion, malathion, carbaryl, captan, and atrazine. For the other 13 pesti-
cides investigated, practical chemical methods for disposal are not available
at the present time. In most cases, the only available practical method
for the disposal of small quantities of these pesticides is either land
burial or ground surface disposal, although incineration at high tempera-
tures (above 1000 C for a minimum of 2 sec) is the preferred disposal
method in all cases.
The personal protection equipment needed in the disposal of pesticides
are given in Table 6. The type and quantity of decontaminant solution as
well as the contact time recommended for the detoxification of the seven
pesticides where chemical methods are applicable are given in Table 7. The
recommended contact time is based on the calculated residence time required
to cause 99.9 percent degradation of the pesticide. A minimum of 15 minutes
has been allowed for the degradation reaction to complete even for reactions
that are practically instantaneous. Also, in the case of wettable powder
and dust formulations, a contact time of twice the nominal requirements is
recommended to allow for the diffusion and absorption of the reactants into
the solid particulates. In the case of diazinon, it may also be noted that
alkali treatment is recommended over acid treatment as the preferred chemical
disposal method. This is because acid treatment of diazinon could lead to
Preceding page blank 23
-------
TABLE 6
PERSONAL PROTECTION EOUIPMENT FOR PESTICIDE DISPOSAL*
The decontaminant solution recommended for the chemical detoxification of
pesticides and pesticide containers in most cases is strong caustic that
can severely burn skin, eyes, or any body tissue. In addition, inhalation
and skin contact with the pesticides, and especially the organophosphates,
is extremely dangerous. To avoid contact with the decontaminant solution
and the pesticide in the disposal of small quantities of pesticides or
pesticide containers, the following protective equipment is recommended:
1. Impervious or rubber head covering.
2. Protective eye goggles.
3. Organic vapor respirators, cartridge type.
4. Washable work clothing.
5. Natural rubber gloves.
6. Latex rubber apron, ankle length.
7. Rubber work shoes or overshoes.
It should be noted that most household gloves deteriorate when handling
organophosphates and therefore should not be used. Also, leather shoes
should not be worn. The organic vapor respirators could be any type
approved by the U.S. Department of Agriculture.
The rubber gloves, shoes, apron, and head covering may be obtained through
a rubber goods house or safety equipment companies. The eye goggles, work
clothing and organic vapor respirator may be obtained from safety equip-
ment companies or sometimes through the Sears and Roebuck farm catalog.
* References 10, 11, 12, and 13.
24
-------
TABLE 7
RECOMMENDED DECONTAMINANT SOLUTION AND CONTACT TIME FOR THE
CHEMICAL DETOXIFICATION OF SELECTED PESTICIDES
Pesticide
Formulati on*
Decontaminant
Solution
Ratio of Decontaminant
Solution to Formulation
Contact
Time
Naled
8 lb/gal EC
4% D
5% NaOH -
50% ethanol
10:1 by volume
1/2 gal to 1 lb
15 min
30 min
Di azinon
60% EC
25% EC
WP, D
5% NaOH -
50% ethanol
10:1 by volume
5:1 by volume
1/2 gal to 1 lb
40 min
40 min
80 min
Guthion
2 lb/gal EC
50% WP
5% NaOH -
50% ethanol
5:1 by volume
1/2 gal to 1 lb
15 min
30 min
Malathion
5 lb/gal EC
WP, D
5% NaOH -
50% ethanol
10:1 by volume
1/2 gal to 1 lb
15 min
30 min
Carbaryl
4 lb/gal OS
2 lb/gal EC
1 lb/gal EC
WP, D
5% NaOH -
50% ethanol
10:1 by volume
10:1 by volume
5:1 by volume
1 gal to 1 lb
15 min
15 min
15 min
30 min
Captan
WP, D
10% NaOH
1 gal to 1 lb
30 min
Atrazine
WP
10% NaOH
1 gal to 1 lb
48 hr
*EC - emulsifiable concentrate, D - dust, WP - wettable powder, OS - oil solution.
-------
highly toxic degradation products when insufficient water is present. In
the disposal of small quantities of naled, diazinon, Guthion, malathion,
carbaryl, captan and atrazine, the information provided in Table 7 is to
be used in conjunction with the information on recommended personal protec-
tion equipment (Table 6) and the Pesticide Disposal Procedure by Alkali
Treatment presented in Table 8.
As discussed previously, there are no practical chemical detoxification
techniques for the other 13 pesticides investigated. For these pesticides,
*
incineration or burial in a specially designated landfill are the only
environmentally adequate methods of disposal. However, there is a scarcity
of both pesticide incinerators and specially designated landfills in opera-
tion to serve the farm communities and the general public, and land burial
or ground surface disposal are the only other options suitable for the
disposal of small quantities of these pesticides. These alternate methods
for the disposal of small quantities of the 13 pesticides are given in
Table 9. It may be noted that ground surface disposal at herbicidal dosage
is recommended for alachlor instead of land burial because at higher con-
centrations, alachlor could conceivably react with nitrites in the soil to
form a nitrosoamine, a suspected carcinogen. Also, acid treatment is
recommended for picloram prior to land burial. Picloram is usually formu-
lated as an aqueous solution containing its potassium salt, which is
extremely water-soluble, mobile, and persistent in soil. Conversion of
the potassium salt of picloram to the acid form by the addition of a
mineral acid therefore reduces the potential for water contamination.
For the decontamination of glass and metal pesticide containers, the
NACA triple rinse and drain procedure (Appendix D) should be followed
whenever applicable. To decontaminate glass and metal containers for
naled, diazinon, Guthion, malathion, carbaryl, captan and atrazine, the
use of a caustic soda rinse solution is also effective and is recommended
*"Specially designated landfill" is defined in 40CFR Part 165 as a
landfill at which complete long term portection is provided for the quality
of surface and subsurface waters from pesticides, pesticide containers, and
pesticide-related wastes depositied therein, and against hazard to public
health and the environment.
26
-------
TABLE 8
PESTICIDE DISPOSAL PROCEDURE -
CHEMICAL DETOXIFICATION BY ALKALI TREATMENT
This procedure is only applicable to seven of the 20 pesticides investigated
in the present study: naled, diazinon, Guthion, malathion, carbaryl, captan,
and atrazine. Do not use this procedure for other pesticides since decom-
position products are unknown and may be harmful. The quantity of decon-
taminant solution to be used in given in Table 7. Note that caustic soda
(lye) absorbs moisture and should be stored in a tightened container. The
disposal procedure is outlined as follows:
1. Use personal protection equipment (Table 6).
2. Carefully mix water, ethanol (if recommended) and caustic soda
(lye) in a container to make up the recommended decontaminant
solution (Table 7). Note that the reaction between caustic
soda and water generates heat and splattering may occur. To
make up 1 gal of the 5% NaOH - 50% ethanol solution, use 1 cup
of caustic soda with 2 qts of ethanol and 1-3/4 qts of water.
To make up 1 gal of the 10% NaOH solution, use 2 cups of caustic
soda with 3-1/2 qts of water.
3. Place pesticide requiring disposal in a 5 gal metal container.
The container should be one that has been used for the same type
of pesticide or one that has not been previously used for pesti-
cides and other chemicals. Add the recommended amount of decon-
taminant solution (Table 7) to the pesticide. Do not fill up
more than half of the container. Larger quantities of pesticides
should be disposed of in several smaller batches.
4. Tighten the bungs and other closures. Rotate the container care-
fully to promote the mixing between the pesticide formulation and
decontaminant solution.
5. Let the container and reaction mixture stand for at least
15 minutes with occasional agitation. Consult Table 7 for the
recommended contact time for each pesticide formulation.
27
-------
TABLE 3 (CONTINUED)
6. Remove all bungs and closures and drain the reaction product
mixture into a pit or trench at least 18 inches deep, located
in non-crop land away from water supplies. Cover with earth.
7. Flush inside and outside of container with clear water.
8. Tighten all bungs and closures. Puncture the container with a
pick axe or chisel and crush immediately and recycle for scrap
to a steel melting plant. If container recycle cannot be accom-
plished, bury the container at least 18 inches deep in an isolated
area away from water supplies or at an approved dump site.
28
-------
TABLE 9
ALTERNATE METHODS FOR THE DISPOSAL OF
SMALL QUANTITIES OF SELECTED PESTICIDES
Pesticide
Disposal Method
Dursban
Land burial
Methyl parathion
Land burial
Maneb
Land burial
A1 achlor
Ground surface disposal
Diuron
Land burial
Picloram
Land burial with acid
treatment
Trifluralin
Land burial
Methoxychlor
Land burial
Chlordane
Land burial
Toxaphene
Land burial
2,4-D
Land burial
Ami ben
Land burial
Pentachlorophenol
Land burial
29
-------
as an alternate procedure. The caustic soda rinse procedure is described
in Table 10. To decontaminate glass and metal containers for other pesti-
c1des9 the only alternate procedure is the use of a detergent rinse solution
as described by Lawless et alJ This procedure is identical to the caustic
soda decontamination procedure (Table 10) except that no caustic soda is
added and the rinse procedure is repeated once. The rinse solution for
this procedure contains undegraded pesticides and must be disposed of by, in
order of preference: (i) incineration; (ii) burial at an approved landfill;
(iii) burial in an isolated area away from water supplies.
The preferred method for the disposal of combustible pesticide con-
tainers is by burning in approved incinerators. Included in this category
are paper bags, fiber drums, burlap bags, cloth bags, cardboard boxes,
fiber boxes, wooden boxes, and plastic bags. If this cannot be accomplished,
the containers should be emptied as thoroughly as possible, crushed (if
applicable), and buried in approved landfills or at least 18 inches deep in
an isolated area away from water supplies. Open burning of the used pesti-
cide containers can.be very hazardous and is not recommended. In the case
of herbicides, open burning may result in the emission of vapors that could
cause damage to nearby vegetation.
Small empty aerosol cans for pesticides should not be incinerated
or burned since they may contain explosive amounts of residual hydrocarbon
propellantJ These can be disposed of either through the household trash
collection service or be buried at least 18 inches deep in an isolated area
away from water supplies.
30
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TABLE 10
PESTICIDE CONTAINER DECONTAMINATION PROCEDURE
WITH CAUSTIC SODA
This procedure is only applicable to empty glass and metal containers for
naled, diazinon, Guthion, malathion, carbaryl, captan and atrazine. Do
not use this procedure for containers of other pesticides without con-
sulting the pesticide manufacturer or EPA personnel. The procedure is
outlined as follows:
1. Use personal protection equipment (Table 6).
2. Drain container as completely as possible to spray tank or
to another container for chemical detoxification. In the
latter case, do not mix the pesticide with other types of
pesticide formulations. Follow the pesticide detoxifica-
tion procedure described in Table 8.
3. Carefully add water, detergent and caustic soda (lye) and
tighten the bungs and other closures. The amount of rinse
solution to be added depends on the container size.
a. container size less than 5 gal - 1 pt water, 1 table-
spoon detergent, 1 teaspoon caustic soda.
b. 5 gal containers - 2 qt water, 2 tablespoons detergent,
1/2 cup caustic soda.
c. 15 gal containers - 1-1/2 gal water, 1/4 cup detergent,
1/2 lb (approximately 1 cup) caustic soda.
d. 30 gal containers - 3 gal water, 1/2 cup detergent,
1 lb (approximately 2 cups) caustic soda.
e. 55 gal containers - 5 gal water, 1 cup detergent, 2
lb (approximately 4 cups) caustic soda.
4. Rotate the container carefully to wet all inner surfaces
with the rinse solution.
5. Let the container stand 15 minutes with occasional agitation.
31
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TABLE 10 (CONTINUED)
6. Remove all bungs and closures and bury the rinse solution
at least 18 inches deep in an isolated area away from water
supplies.
7. Flush inside and outside of container with clear water.
8. For 30 and 55 gal steel containers, replace closures and
secure tightly and send the containers to an approved drum
reconditioner (check with State Department of Agriculture
for list) or recycle as scrap into a steel melting plant.
For 1 gal and 5 gal steel containers, puncture with a pick
axe or chisel and crush immediately and recycle for scrap
to a steel melting plant. For glass containers break or
crush into large container (such as 55 gal open headed
drum with cover) and recycle for scrap to a glass melting
plant. If container recycle cannot be accomplished, the
container should be crushed and buried at least 18 inches
deep in an isolated area away from water supplies or at
an approved dump site. Do not reuse container.
32
-------
4. CONCLUSIONS AND RECOMMENDATIONS
The present study has demonstrated that chemical detoxification can
be an effective method for the disposal of small quantities of excess pes-
ticides and the decontamination of pesticide containers. A total of twenty
pesticides representative of different chemical classes were investigated,
and the results of the study indicated that alkali treatment is a practical
degradation/detoxification technique for naled, diazinon, Guthion (azinphos-
methyl), malathion, carbaryl (Sevin), captan, and atrazine. The effects of
chemical treatment on these seven pesticides and the reasons for recommend-
ing alkali treatment are summarized in Table 11. Detailed disposal proced-
ures for these pesticides based on alkali treatment have been developed and
presented in Section 3.
No.practical chemical degradation/detoxification methods were identi-
fied for the disposal of Dursban, methyl parathion, maneb, alachlor (Lasso),
diuron, picloram, trifluralin, methoxychlor, chlordane, toxaphene, 2,4-D,
ami ben(chloramben), and pentachlorophenol. In most cases, chemical methods
were not recommended at the present time for one or more of the following
reasons:
The extent of chemical degradation is unknown or imcomplete.
The identity of the degradation products are unknown.
The environmental hazards of the degradation products are unknown.
The chemical reagents involved are expensive and hazardous.
The chemical degradation products are hazardous.
The effects of chemical treatment on the thirteen pesticides and the speci-
fic reasons for not recommending chemical treatment are summarized in Table
12. For these pesticides, alternate disposal methods based on land burial,
land burial with acid treatment, or ground surface disposal have been pro-
posed and discussed in Section 3. However, with the exception of land
burial for trifluralin and possibly for 2,4-D, the other alternate disposal
procedures prescribed only result in better containment of the hazard and
33
-------
TABLE 11
SUMMARY OF EFFECTS OF CHEMICAL TREATMENT ON PESTICIDES FOR WHICH ALKALI TREATMENT IS RECOMMENDED
Pesticide
Chemical Treatment
Degree of Degradation
Identity and Environmental Hazards of Degradation Products
Naled
(Dibrom)
Alkaline hydrolysis
Complete degradation
The alkaline salts of dimethylphosphoric acid, hydrobromic
acid and dichlorobromoacetic acid formed are nontoxic.
Di azi non
Alkaline hydrolysis
Complete degradation
The alkaline salt of diethythiophosphoric acid and the
2-isopropyl-4-methyl-6-hydroxypyrimidine formed are con-
siderably less toxic than diazinon.
Acid hydrolysis
Complete degradation
In large excess of water, same hydrolysis products are
obtained as in alkaline hydrolysis. However, ^highly
toxic tetraethyl dithio - and thiopyrophosphates have
been found with insufficient water in acid medium.
Chemical oxidation
Complete degradation
Diazoxon formed is equally toxic.
Guthion
(Azi nphosmethyl)
Alkaline hydrolysis
Complete degradation
The alkaline salt of dimethyldithiophosphoric acid and the
anthranilic acid formed are nontoxic.
Chemical oxidation
Complete degradation
Gutoxon formed is equally toxic.
Malathion
Alkaline hydrolysis
Complete degradation
The alkaline salt of dimethyldithiophosphoric acid formed
is nontoxic. The diethyl fumarate formed is not a
cholinesterase inhibitor.
Acid hydrolysis
Slow reaction
The dimethythiophosphoric acid and the 2-mercaptodiethyl
succinate formed are not cholinesterase inhibitors.
Chemical oxidation
Complete degradation
Malaoxon formed is more toxic than malathion.
Carbaryl
(Sevin)
Alkaline hydrolysis
Complete degradation
1-Napthol and methyl amine formed have low toxicity.
Alkaline carbonate formed is nontoxic.
Acid hydrolysis
Very slow reaction
Identity and toxicity of products unknown.
Nitric acid
Unknown
Nitrobenzene and other unidentified products are formed.
Captan
Alkaline hydrolysis
Complete degradation
Tetrahydrophthalimide and alkaline sulfide, chloride and
carbonate are formed. Tetrahydrophthalimide is further
hydrolyzed to phthalic acid.
Acid hydrolysis
Unreactive
- -
Atrazine
Strong alkali
Complete degradation
Hydroxyatrazine formed is herbicidally inactive and will
further decompose in plants to amines and carbon dioxide.
Strong mineral acid
Slow reaction
Hydroxyatrazine is formed.
Weak alkali or acid
Unreactive
-
-------
TABLE 12
SUMMARY OF EFFECTS OF CHEMICAL TREATMENT ON SELECTED PESTICIDES
f"
Pesticide
Chemical Treatment
Deqree of Degradation
Identity and Environmental Hazards of Dearadation Products f
Uursban
(Chi orpyri fos)
Acid or alkaline hydrolysis
Complete degradation
Toxicity of trichlorohydroxypyridine formed unknown. E
Sodium hypochlorite
Complete degradation
Identity and toxicity of products unknown. F
Methyl
Acid hydrolysis
Very slow reaction
p-Nitrophenol formed is toxic. 1
pa rath ion
Alkaline hydrolysis
Complete degradation
p-Nitrophenol formed is toxic.
Chemical oxidation
Complete degradation
Methyl paraoxon formed is more toxic than methyl parathion
for vertebrates.
Chemical reduction
Unknown
0,0-dimethyl 0-4-aminophenyl thiophosphate is nontoxic to
. animals, but total environmental hazards are not known.
Maneb
Strong acids
Complete degradation
Carbon disulfide evolved could be an explosive and toxicity
hazard.
Hydrolysis in weak acids
or alkali
Complete degradation
Ethylene thiourea formed may be carcinogenic.
Chemical oxidation
Unknown
Ethylenethiuram monosulfide formed may lead to ethylene
thiourea.
Alachlor
(Lasso)
Hydrolysis by strong acids
or alkali
Complete degradation
The secondary amine formed may react with nitrites in the
soil to form nitrosoamine, a suspected carcinogen.
Diuron
Boiling with caustic alkalies
or mineral acids
Chemical oxidation
Complete degradation
Unreacti ve
3,4-dichloroaniline and dimethyl amine formed are more toxic
than diuron.
Pi cloram
Sodium hydroxide
Unknown
Decarboxylation and Dartial dechlorination of picloram.
Complete identity and toxicity of products unknown.
Tri fl ural in
Acid or alkaline hydrolysis
Chemical oxidation
Unreacti ve
Unreacti ve
Methoxychlor
Alkaline hydrolysis
Chemical oxidation
Slow reaction
Unreacti ve
Environmental hazards of the 1 ,l-dich!oro-2,2-bis (p- j
methoxyphenyl) ethylene formed are not known.
I Cblordane
Alkaline hydrolysis
Unknown
Partial dechlorination leads to the splittina out of one i
or two chlorine atoms. Environmental hazards of products
unknown.
-------
TABLE 12
(CONTINUED)
Pesticide
Chemical Treatment
Deqree of Deqradation
Identity and Environmental Hazards of Degradation Products
Chlordane
(Continued)
Chemical reduction
Substantial degradation
Identity and toxicity of products unknown.
Toxaphene
Alkaline hydrolysis
Partial dechlorination
Identity and toxicity of products unknown.
2,4-D
Prolonged boiling with HBr
or HC1
Complete degradation
2,4-Dichlorophenol formed is extremely susceptible to photo-
decomposi tion.
Sodium hypochlorite or
gaseous chlorine at pH 3
Complete degradation
Identity and toxicity of products unknown.
Nitric acid
Unknown
Environmental hazards of the 2,4-dicbloro-5-nitrophenoxy-
acetic acid formed unknown.
Hydrogen peroxide
Unreacti ve
Ami ben
{Chloramben)
ficid or alkaline hydrolysis
Chemical oxidation
Un reactive
Unreacti ve
Sodium hypochlorite
Complete degradation
Identity and toxicity of products unknown.
Pentachlorophenol
Chemical oxidation
Complete depradation
Chlorani 1 formed is a disinfectant.
Chlori nation
Complete degradation
Hexachlorophenols formed are fungicidal.
-------
cannot be considered totally environmentally acceptable. The preferred
disposal method for these pesticides is by incineration.
In Table 13, the final recommendations on the disposal of small quanti-
ties of each of the twenty pesticides are summarized according to their
chemical classification. It may be observed that all the pesticides that
are amenable to alkali treatment belong to either the organophosphates,
the carbamates, the imides and hydrazides, or the triazines categories.
In general, the other pesticides in these categories are also readily
decomposed by alkali treatment. It is important to recognize, however,
that the nature of the degradation products is highly dependent on the
other functional groups constituting the pesticide. It is thus possible
to produce degradation products of various degrees and types of hazard
when pesticides of the same chemical class are subjected to alkali treat-
ment. The applicability of alkali treatment as a disposal method for
pesticides must therefore be assessed on an individual basis.
On the other hand, knowledge of the hazards associated with the chemi-
cal disposal of a specific pesticide can often serve as warning against
utilizing the disposal method for other pesticides of the same chemical
class. For example, it was pointed out that the mildly acidic, neutral or
alkaline hydrolysis of maneb would result in the formation of carcinogenic
ethylene thiourea. The same hazard is also present when the other deriva-
tives of ethylenebisdithiocarbamic acid, such as zineb and nabam, are sub-
jected to hydrolysis except in strong acid solutions. In the hydrolysis
of diuron, the dimethyl amine and 3,4-dichloroaniline formed are both of
higher mammalian toxicity than diuron. Similarly, in the hydrolysis of
other substituted ureas, such as fenuron, monuron and neburon, the dialkyla-
mine and aniline or chloroaniline formed are all of higher mammalian toxicity
than the starting pesticide compounds.
As noted from Table 13, chemical treatment is not recommended for any
of the halogen-containing pesticides. This is because most of the halogen-
containing pesticides are polyhalogenated and it is difficult to remove more
than one halogen atom from the pesticide compound by practical chemical
methods. Furthermore, the identity and the environmental hazards of the
37
-------
TABLE 13
SUMMARY OF RECOMMENDED METHODS FOR THE DISPOSAL OF
SMALL QUANTITIES OF SELECTED PESTICIDES
Pesticide Class
Pesticide
Recommended
Disposal Method
I. Phosphorus-conHining
pesticides
Phosphates and
phosphonates
Naled
Alkali treatment
Phosphorothioates
Diazinon
Alkali treatment
Phosphorothioates
Methyl parathion
Land burial
Phosphorothioates
Dursban
Land burial
Phosphorodithioates
Guthion
Alkali treatment
Phosphorodi thioates
Malathion
Alkali treatment
II. Nitrogen-containing
pesticides
Carbamates
Carbaryl
Alkali treatment
Dithiocarbamates
Maneb
Land burial
AniTides
Alachlor
Ground surface disposal
Imides and hydrazi des
Captan
Alkali treatment
Ureas and uracils
Diuron
Land burial
Triazines
Atrazine
Alkali treatment
Ami nes
Picloram
Land burial with acid
treatment
Nitro compounds
Trifluralin
Land burial
III. Halogen-containing
pesticides
DDT group
Methoxychlor
Land burial
Chlorophenoxy compounds
2,4-D
Land burial
Aldrin-toxaphene group
Chlordane
Land burial
Aldrin-toxaphene group
Toxaphene
Land burial
Dihaloaromatic
compounds
Ami ben
Land burial
Highly halogenated
compounds
Pentachlorophenol
Land burial
38
-------
partially dehalogenated products are almost always unknown. Thus there is
a definite need for catalysts that would facilitate the dehalogenation
process.
The above discussion and the detailed analysis presented in the Appen-
dices lead to the conclusion that there is presently insufficient informa-
tion to develop chemical detoxification procedures for most of the pesti-
cides. Consequently, it is recommended that future research be carried out
in the following areas:
t Determine the toxicity of the degradation products from the acid
and alkaline hydrolysis of Dursban.
Determine the identity and environmental hazards of the degrada-
tion products of Dursban, 2,4-D, and amiben by sodium hypochlorite
treatment.
Determine the rate of alkaline hydrolysis of picloram, methoxychlor,
chlordane, and toxaphene, and the identity and environmental hazards
of the degradation products.
t Investigate the detoxification of methyl parathion and chlordane
by chemical reduction methods.
Develop inexpensive and safe catalysts for the dechlorination of
chlorinated hydrocarbon pesticides.
Investigate other practical chemical methods for the disposal of
maneb, alachlor, diuron, and picloram.
t Determine the identity and environmental hazards of the degradation
products from the treatment of organophosphorus and carbamate pes-
ticides by a decontaminant solution of monoethanolamine (MEA) in
dipropyleneglycol monomethyl ether (DPGME).
Expand the study of chemical disposal methods to other pesticides.
39
-------
APPENDICES
Preceding page blank
-------
APPENDIX A
CHEMICAL METHODS FOR THE DEGRADATION/DETOXIFICATION
OF PHOSPHORUS-CONTAINING PESTICIDES
A.1 GENERAL REVIEW OF APPLICABLE DISPOSAL METHODS
The organophosphorus compounds constitute one of the most important
classes of present day pesticides. The scale of use of the organophosphorus
pesticides is gradually surpassing that of the organochlorine pesticides
because of their lesser persistence in the environment and rapid degradation
to supposedly harmless products. In reality, the decomposition of some
organophosphorus pesticides may lead to more or equally toxic components.
For example, chemical oxidation of parathion leads to the more toxic para-
oxon, whereas hydrolysis leads to the equally toxic p-nitrophenol. It is
therefore important to know both the identity and the hazard properties of
the end degradation products before any chemical detoxification procedure
could be reconmended.
The organophosphorus pesticide is a tertiary phosphate or thiophosphate
ester represented by the general structural formula:
R0\ ^O(S)
ro/Pno-x
(S)
where R is usually an ethyl or methyl group and X is an organic radical.
For the organophosphorus pesticides, hydrolysis in many cases results in
nontoxic decomposition products and is therefore considered a general de-
toxification technique for this class of compounds. The hydrolysis could
take place in either acid, neutral, or alkaline solutions. In hydrolysis,
whether the P-O(S) or (S)O-X bond is ruptured depends on both the structure
of the pesticide and the hydrolytic conditions. In alkaline solutions, the
P-O(S) bond is broken and the (S)O-X is usually replaced:14
Pages 42, 43, and 44 are blank
45
-------
R(K ^°(s) R0\
.pf + OH- - /P\ + xo;
ro xo-x RO noh (S)
(S)
J
In acid hydrolysis, however, the initial step involves the rupture of the
(S)O-X bond, followed by additional hydrolysis of the secondary esters to
14
primary esters:
R0\ /-0(s) . R0\ ^-0(s) +
p + H ~ /PN + X
RO 0-X RO OH
(S) | (S)
Primary ester
It should be noted that the cleavage of P-O(S) or the X-O(S) bond also
depends on the nature of the X group and the general rule for the acid
and alkaline hydrolysis of organophosphorus pesticides described above is
not always valid.
The rate of hydrolysis of organophosphorus pesticides under similar
conditions is dependent on the chemical nature of the substituents R and X.
In general, the substituents that render the phosphorus atom more electro-
positive also increase the rate of hydrolysis, unless steric effects inter-
fere, thus:^' 15, 16, 17
« Pesticides where R is a methyl group hydrolyze more rapidly than
their ethyl analogues. For example, methyl parathion hydrolyzes
at a faster rate than parathion.
t The substitution of P=0 for P=S results in a compound of greater
hydrolyzability. For example, paraoxon hydrolyzes at a faster
rate than parathion.
46
-------
-t i ¦?;: useful rrf i :ig rhemi csl >«. ti c. w-ioxi -
-i - n ''i itriiH .t*:. hi: u^S" the a! os co.ivercitiy r.ht
'h-ir>.s *«-): ut \i. ; . - r, -:?!' «..;H M-'OdU,' t t.T;fv-.;'v, r-i t.J. 3!.-;.i or
-; i-ial, <'t rs^Mrifrr <>j{»i L>» v>n:--'«ien?«;i. !/»<» c-Df«i ino^i ,*» :;; i Ao :?;/
nyuro 0"':i 3 :1;- ir*' ;i;C". \xr;K,o-iiH f >u;?1d in ?!-<*?» raoiff
de-ridii;cr 01 ' 3*: rryrno?Mpi;.i>jr1--" pe?iic;der; ir- Mn? cr.'s,
M'se rale of hyd^f/tv"-.ui of orgatiuphi-sphorus pestlcities u; ahso strolly
«'' liscei'sC-'-ri!;. Almost ir-.y .-nimbly the reaction Dctwef:n an oroanopSospborifs
coiMjjoiifi'"- 8^ri kaiei' > ttCio or base is fOt-'i'Mj to obey second cotter kinetics,
-r-t tnt /'.its:; ; j" report; 0:13; to both tsv;% concent ration ot th? psscicidt!
. VH- ¦> K
.-.r-d tre t.vf.iM'Ptr.itlCri Ot hydroxy! ot n-'drcwti ion, ' Tnus the rate
rwtianOM 'la;: be r^f^SeP^d ¦
r) » %(a-iHb-*} r
*lsf
rr;'fv: ;1 i d ;j»"e t!l r. 1 r? : 11 a 1 CC'fiCtiBt :"3t1 Ofl 0'f ,? r Q51 ?Upf iOSC'^O HIS ;;e$UCn"ki
>:;i 'r.e iiVijrr;;c/l (or » ydm-jen ; ;0su r;j5pf?Qt'; ve 1 y; x is .^crease in con¦
;rrj:. gfti:r t.:. k is the reaction rate "cr^tant. Infeg' aUon erf
!-'i? Tdtt.il Srrjation 'J: l-atls tO
J-
i-t.
^ L_ i£i*i
'(a-x) b
r. '. . {* ? v, th-_ jiti i ri I ri !¦ ?d 10 rrt-an: ir.ri t'nr tine
! 'rr r.- ir^sltj l f " X{i!.'p! '. nf ,:,n <,-qa ¦nph-i:!oh" r
r^L c i^e Is r<7- L-
'0.5 c >~(l' 31
jLb-a )
n
s >i.
-!! ?.
j :>»" ¦.» v;; ,fei r.^d fr,r '¦*1 y^r~i ...t tiri-l ;*
rq-rt.fO -UjCH r'Li> pt<.U>.e a'S, : & ett i vtf'
,cv'j.Ii ;"c>
-------
(5)
4R
-------
the compounds to phosphoric acid.^ Since perchloric acid solutions
may form sensitive powerful explosive mixtures with organic materials
and the anhydrous acid decomposes at ambient temperature and explodes
on contact with most organic materials, there are no practical chemical
oxidation methods to detroxify organophosphorus pesticides directly.
Oxidation or halogenation of organophosphorus pesticides followed
by chemical hydrolysis, on the other hand, is a detoxification procedure
that deserves special consideration. Both oxidation and halogenation
decrease the stability of the organophosphorus pesticide to hydrolysis,
although the initial oxidized or halogenated products are generally
more toxic. Thus, diazinon may be oxidized to diazoxon which hydro-
lyzes more readily. In water an access of chlorine rapidly leads to
complete breakdown of Schradan to nontoxic compounds, presumably via
the hydrolysis of the chlorinated products.^ Hypochlorites have there-
fore been used to clean equipment contaminated with Schradan and Dimefox.
A. 2 CHEMICAL METHODS FOR THE DEGRADATION/DETOXIFICATION OF NALED
Naled (Dibrom, 0,0-dimethyl 0-2,2-dichloro-l,2-dibromoethyl phosphate)
is an active insecticide for the control of both sucking and chewing
insects and is manufactured by the bromination of dichlorvos (DDVP). The
usual formulations for naled include the 8 lb/gal emulsifiable concentrate
(Ortho Dibrom 8 Emulsive) and the 4 percent dust (Ortho Dibrom Dusts).19
Naled is stable in brown glass containers but in the presence of
metals and reducing agents rapidy loses bromine and reverts to dich-
lorvos:3, 20
>1 II
(CH30)2P0CHBrCCl2Br ~ (CH30)2P-0CH=CC12 + Br2
The presence of dichlorvos must therefore be taken into consideration in
the recormaendation of any detoxification procedure for naled.
With respect to hydrolysis, naled is more stable than dichlorvos.
The hydrolysis of naled results in the formation of dimethyl phosphoric
49
-------
acid, hydrobromic acid, and dichlorobromoacetic acid. For dichlorvos,
the hydrolysis products are dimethyl phosphoric acid and dichloroacetalde-
hyde.^' ^ In the presence of NaOH, the sodium salts of the acids would
be formed. Since dimethylphosphoric acid and its sodium salt and the
sodium salt of dichlorobromoacetic acid are practically harmless, and
dichloroacetaldehyde rapidly decomposes and evaporates, no toxic residues
21 23
would remain from the hydrolysis products of naled and dichlorvos. '
The rate of hydrolysis of naled has been reported to be about 10
percent per day in ambient water. ^ Metcalf indicated that naled is des-
25
tructively hydrolyzed in water in about 2 days. Using the more con-
servative estimate of 10 percent hydrolysis per day and the bimolecular
reaction rate model described in A.l, the time required to degrade
99.9 percent of the naled in a 8 lb/gal formulation with 1 N NaOH was
calculated to be less than 0.5 min, when the volume-to-volume ratio of the
NaOH decontaminant solution to naled formulation was ten to one. It was
also noted that a ten to one volume-to-volume ratio provides approximately
30 percent more than the stoichiometric amount of NaOH required to neutral-
ize the acids formed from the hydrolysis of naled. Since dichlorvos
hydrolyses at a faster rate than naled, any dichlorvos resulting from the
decomposition of naled in the pesticide formulation would also be hydro-
lyzed almost instantaneously in the IN NaOH. For the 4 percent dust formu-
lation of naled, a two to one volume-to-volume ratio of 1 N NaOH solution
to naled dust is more than adequate to detoxify the pesticide. In the
case of both the emulsifiable concentrate and dust formulations, however,
the naled must first be dissolved into the aqueous phase before the neu-
cleophilie attack by the hydroxyl ion can occur. To accomplish this, it
is recommended that a ethanol be added to make up a 50 percent ethanol
solution in IN NaOH.26
A decontaminant solution containing 12.5 percent of monoethanolamine
(MEA) in dipropylene glycol monomethyl ether (DPGME) solvent has also
18
been developed to detoxify naled. In the experiments conducted, 85
percent technical naled was exposed to the decontaminant solution in a
volume-to-volume ratio of 10 parts decontaminant to the one part naled.
50
-------
Naled was shown to be destroyed completely after 30 min, and the data
obtained from the subsequent fish studies indicated that the reaction
product mixture has low toxicity to fish, with a 48-hour TL of 2109
ppm for mosquito fish. The MEA-DPGME solution has been used effectively
to decontaminate spray equipment for naled and should be applicable to
the decontamination of small quantities of naled formulations and used
naled containers.
For the decontamination of naled containers, the triple rinse and
drain procedure developed by the National Agricultural Chemicals
Association (NACA) is recommended (Appendix D). The use of a rinse solu-
tion containing caustic soda and detergent may also be considered. These
decontamination procedures are described in detail in Section 3.
A.3 CHEMICAL METHODS FOR THE DEGRADATION/DETOXIFICATION OF DIAZINON
Diazinon (0,0-diethyl 0-(2-isopropyl-4-methylpyrimidyl-6)
thiophosphate) is used to control various plant pests and animal para-
sites and is marketed in the form of emulsive concentrates, wettable
powders, dusts and granulated formulations. The typical formulations
include 5 percent and 10 percent granules (Basudin 5 and Basudin 10),
25 percent and 60 percent emulsive concentrates (Basudin 25 and
Basudin 60), and 40 percent wettable powders (Basudin 40).
Diazinon is miscible with ethanol, acetone, xylene, and soluble in
petroleum oils. In an excess of water, the principal products of diaz-
inon are diethylthiophosphoric acid and 2-isopropyl-4-methyl-6-hydroxy-
21 27
pyrimidine (IMHP) under both acidic and alkaline conditions. '
CH,
A
H0 CgHy-iSO
The major hydrolysis product IMHP has an acute oral LD^q value of 2700
51
(c2h5o)2p-o
h2o
(c2h5o)2poh
CgHy-l'SO
-------
14
mg/kg for mice and is considerably less toxic than diazinon.
Dietbylthiophosphoric acid is also not known to be toxic. Chemical
hydrolysis can therefore be considered a possible method for the disposal
of diazinon.
The kinetics of hydrolysis of diazinon have been studied by a number
of investigators. In a study conducted on aqueous solutions of diazinon
with 3.5 percent acetone at concentrations of 100 mg/1, Weiss and
Gakstatter determined the half-lives of diazinon as 25, 45 and 40 days at
pH, 6, 7 and 8, respectively, under experimental temperature conditions
28
of 18 to 15 C. Ruzicka et al reported the half-life of diazinon at
15
70 C in ethanol - pH 6 buffer solutions as 37 hours. The 30 percent
ethanol was used to improve pesticide solubility. Konrad et al studied
29
the effect of pH on rates of diazinon hydrolysis in aqueous systems.
At pH 6 diazinon was found to be quite stable to hydrolysis, but at pH 2
hydrolysis was extremely rapid. Cowart et al found 46.3 percent diazinon
remaining after two weeks in a neutral aqueous solution at room tempera-
Of]
ture. Gomma et al determined the hydrolysis rates of diazinon and
27
diazoxon at five pH values and at a temperature of 20 C. In Table 14,
the half-lives of diazinon at different pH values are shown with the
calculated bimolecular rate constants for hydrolysis. It is seen that
diazinon is quite stable in the pH range of 5.0 to 9.0, although the
hydrolysis process is rapid under acidic (pH <3.1) or alkaline conditions
(pH >10.4). For acid and alkaline hydrolysis, the bimolecular rate con-
stants presented in Table 14 were calculated as:
In 2
k = ; for pH < 7
and
Vs <0H >
In I
k = 7 for pH >7
fc0.5 ' ^
52
-------
TABLE 14
EFFECT OF pH ON THE HYDROLYSIS
RATE OF DIAZINON AT 20 C
pH
Half-life
Bimolecular
Rate Constant
(l/mole-hr)
Reference
2.0
83.3 min
49.9
Konrad et al^
3.1
706.1 min
74.2
Gomma et al^
4.0
31 hr
223.5
Konrad et al
5.0
740.7 hr
93.6
Gomma et al
6.0
25 days
1155.2
28
Weiss and Gakstatter
6.0
37 hr
18733.7
15
Ruzicka et al
7.0
45 days
-
Weiss and Gakstatter
7.0
302.5 hr
-
Cowart et al
7.4
4435.8 hr
-
Gomma et al
8.0
40 days
722.0
Weiss and Gakstatter
9.0
3263 hr
21.2
Gomma et al
10.4
144.9 hr
19.0
Gomma et al
53
-------
where (H+) and (OH-) are the hydrogen and hydroxyl ion concentrations and
*0 5 half-life °f diazinon at the corresponding pH value. It may
also be noted from Table 14 that the value of the rate constant varies
under both acidic and alkaline conditions,* indicating either conflicting
data or the inadequacy of the bimolecular reaction rate model to describe
the chemical hydrolysis of diazinon. On the other hand, the values of the
rate constants calculated from the experimental data of Gomma et al do
confirm the bimolecular reaction rate model and their data generally
provides more conservative estimates for the k values. Using the Gomma
et al k values and the bimolecular reaction rate model, the times required
to degrade 99.9 percent of the diazinon in the 60 percent and 25 percent
emulsive concentrate formulations have been calculated for both acid and
alkaline hydrolysis conditions. The results of these calculations are
presented in Table 15, and indicate that either IN HC1 or IN NaOH may be
employed as the decontaminant solution to detoxify diazinon, although
acid hydrolysis is several times more rapid than alkaline hydrolysis. For
practical detoxification of the emulsive concentrates, granular or powder
formulations of diazinon, it is recommended that ethanol be added to make
up a 50 percent ethanol solution in IN HC1 (or IN NaOH), as the diazinon
must be first dissolved in the aqueous phase before the hydrolysis reaction
can occur. Also, a volume-to-volume ratio of ten parts of decontaminant
solution to one part of the pesticide formulation is recommended. The
large excess of decontaminant solution is essential since small amounts
of the highly toxic tetraethyl dithio- and thiopyrophosphates have been
21
found with insufficient water in acid medium. Tetraethyl dithiopyro-
phosphate (sulfotepp) has an acute oral LD(-n value of 5 mg/kg for rats,
21
whereas the LD^ of tetraethyl monothiopyrophosphate is 0.5 mg/kg.
The effect of temperature on the hydrolysis rate constants has also
27
been determined by Gomma et al. The data agreed with the Arrhenius
equation and showed the half-lives of diazinon at 60 C as 46.7 min at
*However, since the mechanism for acid hydrolysis is different from alka-
line hydrolysis, the value of the rate constant for acid hydrolysis is also
different from that for alkaline hydrolysis.
54
-------
TABLE 15
TIME REQUIRED FOR 99.9 PERCENT
DEGRADATION OF DIAZINON AT 20 C
WITH CHEMICAL HYDROLYSIS
Diazinon
Formulations
Decontaminant
Solution
Volume-to-volume ratio
of Decontaminant Solution
to Formulation
Time Required
for 99.9%
Degradation
60% e.c.
IN
NaOH
10:1
30.2
min
25% e.c.
IN
NaOH
10:1
26.2
min
25% e.c.
IN
NaOH
5:1
31.6
min
25% e.c.
IN
NaOH
3:1
40.8
min
60% e.c.
IN
HC1
10:1
7.8
min
25% e.c.
IN
HC1
10:1
6.7
min
25% e.c.
IN
HC1
5:1
8.1
min
25% e.c.
IN
HC1
3:1
10.5
min
55
-------
pH 3.1 and 12.4 hr at pH 10.4. However, since the rate of hydrolysis of
diazinon is reasonably rapid at 20 C in either IN HC1 or IN NaOH solution
(Table 15), there appears to be no need to further enhance the degradation
rate of diazinon by raising the reaction temperature.
20
Diazinon is susceptible to oxidation. The oxidized product dia-
zoxon is probably of the same toxicity as diazinon but hydrolyses at a
27
faster rate than diazinon. The hydrolysis products of diazoxon are
diethylphosphoric acid and 2-isopropyl-4-methyl-6-hydroxypyrimidine
71
(IMHP). Diethylphosporic acid is nontoxic for both insects and animals
and breaks down completely to phosphoric acid, methane, and carbon diox-
21
ide under the influence of sunlight. Thus it is possible to detoxify
diazinon by first oxidizing the pesticide to diazoxon followed by chemical
hydrolysis.
For the decontamination of diazinon containers, both the NACA triple
rinse and drain procedure (Appendix D) and the use of a rinse solution
containing caustic soda and detergent may be considered. The details of
these decontamination procedures, including the proper disposal of rinse
solutions and decontaminated containers, ere described in Section 3.
A.4 CHEMICAL METHODS FOR THE DEGRADATION/DETOXIFICATION OF DURSBAN
Dursban (chlorpyrifos, 0,0-diethyl 0-3,5,6-trichlop.yridyl
thiophosphate) is an active insecticide for the control of sucking and
chewing plant pests as well as household parasites. The usual formula-
tions include the 2 and 4 lb/gal emulsifiable concentrates (Dursban 2E
and Dursban M), the 0.5 to 15 percent granules, and a number of other
oil-soluble (Dursban 6, Dow Mosquito Fogging Concentrate) and water emul-
sifiable formulations (Dursban 21D).
Dursban has very low solubility in water but is readily soluble in
31
most organic solvents (e.g. 63 g/100 g ethanol at 25 C). Dursban is
stable under normal storage conditions. In acid or alkaline media the
compound is slowly hydrolyzed by water, forming diethylthiophosphoric
21
acid and trichlorohydroxypyridine.
56
-------
n
CI
CI
CI
(C2H5O)2
CI
+ H20 - (C2H50)2P0H +
HO
CI
Although diethylthiophosphoric acid is not biologically active and breaks
down eventually to phosphoric acid, thiophosphoric acid and ethanol,
toxicity data on trichlorohydroxypyridine are not readily available.
For comparison, the acute oral LD^g values for mouse have been given as
235, 1150, and 430 mg/ka for the pentachloro-, 2,3,5,6-tetrachloro- and
32
2,3,5-trichloropyridine, respectively.
The half-lives of Dursban in phosphate buffer solutions at 25 C have
been reported to be 63, 35 and 23 days at pH values of 5, 7 and 8 re-
O]
spectively. With respect to temperature, the hydrolysis rate increases
approximately 3-fold for every 10 C rise, and the half-life of Dursban
23
at pH 7 and 35 C is reduced to 12 days. The temperature effect on
hydrolysis rate can be represented by an energy of activation of 19,500
cal/mole-K for the hydrolysis reaction, and the half-life of Dursban at
pH 7 and 100 C can be calculated as 66.5 min.
In aqueous methanoic solution, the half-life of Dursban is 1,930
r a
days at pH 6.0 and 7.2 days at pH 9.96/ Using this information and the
bimolecular reaction rate model, the time required to degrade 99.9 percent
of the Dursban in a 4 lb/gal formulation with a IN NaOH-methanol solution
was calculated to be 12 min, when the volume-to-volume ratio of the de-
contaminant solution to Dursban formulation was 10 to 1.
Spray mixtures containing less than 1 percent Dursban have been
destroyed with an excess of 5.25 percent sodium hypochlorite in less than
30 min at 100 C and in 24 hours at 30 cJ For concentrated mixtures con-
taining 61.5 percent Dursban, the active ingredient was essentially
destroyed by treatment with 100 volumes of the 5.25 percent sodium hy-
pochlorite solution and steam in 10 minJ However, no information was
given on the identity and toxicity of the degradation products.
-------
In summary, either the IN NaOH-methanol solution or the 5.25 percent
sodium hypochlorite solution and steam may be used to degrade but not
necessarily detoxify Dursban. The identity and toxicity of the degradation
products must be established before either method can be recommended as
the detoxification procedure for Dursban. For small spills or leaks,
V
Dow recommends absorption with materials such as sand and bury the cleaned
33
up waste in locations away from domestic water supplies. For large
spills, Dow recommends barricading the area, elimination of ignition
33
sources and consult the manufacturer.
For the decontamination of Dursban containers the NACA triple rinse
and drain procedure (Appendix D) is recommended. The use of a caustic
soda - methanol or caustic soda - detergent rinse solution will also be
effective in decontaminating the container, but the rinse solutions must
be disposed of either by incineration or burial in an area away from
water supplies.
A.5 CHEMICAL METHODS FOR THE DEGRADATION/DETOXIFICATION OF METHYL PARATHION
Methyl parathion (0,0-dimethyl 0-4-nitrophenyl thiophosphate) is
used for the control of a wide variety of plant pests and is gradually
displacing parathion because of its lower toxicity for mammals. The
usual formulations are emulsions (up to 7.5 lb/gal), wettable powders and
dusts (1 and 2 percent).
Methyl parathion is slightly soluble in paraffinic hydrocarbons
but highly soluble in aromatic hydrocarbons and most organic solvents.
It is hydrolyzed by water and in alkaline medium with the formation of
dimethylthiophosphoric acid and p-nitrophenol:
-------
The rate of hydrolysis of methyl parathion has been investigated
rather extensively. Melnikov reported that at pH 1-5, 50 percent of the
methyl parathion is hydrolyzed in 175 days at 20 C and the rate of hydr©l«
21
ysis in alkaline medium is still greater. Gunther and Blinn reported
the half-life of methyl parathion as 210 min in 0.01 N NaOH at 30 C and
34
32 min in IN NaOH at 15 C. Ketelaar and Ketelaar and Gersmann studied
the alkaline hydrolysis of methyl parathion in water and in 50 percent
acetone and derived Arrhenius expressions for the bimolecular reaction
qc oc
rate constants. ' The half-life of methyl parathion calculated from
these rate constants is 4.4 min in IN NaOH at 20 C and 10.7 min in a
mixture of IN NaOH and 50 percent acetone at 20 C. Muhlmann and Schrader
reported the half-life of methyl parathion at 70 C as 15.4 hr at pH 1 and
22
1.5 hr at pH 9. At 70 C in a 20 percent ethanol - pH6 buffer solution,
15
the half-life of methyl parathion was found to be 8.4 hr. Cowart et al
found 43.5 percent methyl parathion remaining after two weeks in a neutral
30
aqueous solution at room temperature.
The above information indicates that methyl parathion is hydrolyzed.
readily in IN NaOH solution. Alkaline treatment is often the recommended
procedure for decontamination of glass and metal containers and clean up
10-12 37-39
of accidental spills and leaks associated with methyl parathion. '
Presumably, the pesticide residues will undergo hydrolysis and detoxifica-
tion in the strong alkali mixture. However, as has been pointed out,
the p-nitrophenol formed is equally toxic and the container rinse solutions
or the scrubbing and absorption material for spills and leaks must either
be incinerated or be buried in an area away from water supplies.
Oxidizing agents convert methyl parathion to 0,0-dimethyl 0-4-nitro-
phenyl phosphate (methyl paraoxon) which has an oral LD^g of 21 mg/kg for
mouse and is more toxic for vertebrates than the starting methyl
parathion:21, 32
(ch3°)2I°^ N°2 * » (CH30)Jo-hQ-N02 + H2S04
59
-------
In a KMnO^-parathion system, 2,4-dinitrophenol and paraoxon have been
isolated. 14 Similarly, both 2,4-dinitrophenol and methyl paraoxon would
be found in a KMnO^-methyl parathion system, 2,4-Dinitrophenol has an
oral LDj-q of 30 mg/kg for rats and is approximately the same toxicity as
methyl parathi on Thus, chemical oxidation of methy1 parathion 1eads to
degradation products of equal and higher toxicity and is therefore not an
acceptable disposal method.
Reducing agents (e.g., metals in acid medium) convert methyl para-
21
thion to the corresponding amino compound:
S S
(CH30)2Po N02 {CH30)2 lo ^ NH2 + 2H20
The 0,0-dimethyl 0-4 aminophenyl thiophosphate formed is nontoxic to
animals and does not have an insecticidal effect.
In summary, it may be concluded that both chemical hydrolysis and
oxidation result in the formation of toxic products and neither is recom-
mended as a disposal method for methyl parathion. The reduction of methyl
parathion by a decontaminant solution of metal in acid medium (e.g. zinc
in 9 to 1 mixture of acetic and hydrochloric acid) is a potential
chemical detoxification procedure and warrants further investigation.
For the decontamination of glass and metal containers, the triple rinse
and drain procedure developed by NACA is recommended (Appendix D).
Stauffer recommends the use of an aqueous solution of commercial low-
foaming hard water detergent (e.g. Tide, Cheer) in 5 percent trisodium
phosphate or a solution of 14 weight percent bleach (an aqueous solution
38 39
of calcium or sodium hypochlorite) for drum decontamination. ' The
volume of decontaminant solution recommended by Stauffer is 2 gal for 55
gal drums and 0.5 gal for 5 gal cans. Kerr-McGee recommends the use of
a solution of 5 gal water, 1 cup detergent, and 2 lb caustic soda for the
12
decontamination of a 55-gal drum. All three types of decontamination
solutions will be effective in decontaminating the methyl parathion
container, but the rinse solutions now contain toxic degradation products
and must be disposed'of by proper incineration or burial in an area away
from water supplies.
-------
A.6 CHEMICAL METHODS FOR THE DEGRADATION/DETOXIFICATION OF GUTHION
Guthion (azinphosmethyl, 0,0-dimethyl S-(3,4-dihydro-4-keto-l ,2,3-
benzotriazinyl-3-methyl) dithiophosphate) is an insecticide used for the
Control of various pests on cotton, fruits, and many other crops. It 1s
marketed as a 50 percent wettable powder and two 2 lb/gal liquid formula-
tions (Guthion 2S and Guthion 2L).
Guthion is soluable in most organic solvents and is chemically stable
under ordinary storage conditions. In alkaline medium the main products
of Guthion hydrolysis are anthranillc acid and the salt of dimethyldithio-
phorphoric acid:^'
" Jf- OCT
The anthranilic acid is a relatively nontoxic substance which occurs
40
naturally in such foods as grapes, cabbage, etc. The sodium salt of
dimethyldithiophosphoric acid is not a cholinesterase inhibiting material
and will undergo further oxidation and desulfurization reactions to meth-
anol, methane, sodium dithiophosphate, sodium thiophosphate, sodium
phosphate and other nontoxic products. Alkaline hydrolysis can therefore
be considered as a possible method for the disposal of Guthion.
Muhlmann and Schrader studied the effects of pH on the rate of hydro-
lysis of Guthion and Gutoxon (the oxygen analogue of Guthion) at 70 c and
22
the effects of temperature on the rate of hydrolysis in the pH 1-5 range.
As indicated in Table 16, Guthion hydrolysis is slower under acid conditions
than under alkaline conditions. In the pH 1-5 range, the activation energy
for Guthion hydrolysis was calculated to be 23,900 cal/mole from the rate
constants reported by Muhlmann and Schrader. Since the activation energy
for acid hydrolysis is ususally a lot higher than the activation energy for
alkaline hydrolysis, the half-life of Guthion at pH 9 and 20 C can be
estimated from the calculated activation energy for acid hydrolysis and
the data presented in Table 16 as:
61
-------
TABLE 16
EFFECTS OF pH ON THE RATE
OF HYDROLYSIS OF GUTHION
AND GUTOXON AT 70 C
PH
Half-life of
Guthion
(hr)
Half-life of
Gutoxon
(hr)
1.0
24
4.5
2.0
13.5
4.5
3.0
9
4.5
4.0
7.2
4.0
5.0
8.9
4.4
6.0
7.5
4.0
7.0
4.8
2.1
8.0
2.4
0.9
9.0
0.6
62
-------
23900 i 1 1 \
1.9872 ^293.16 " 343.16;
t0 5(pH9, 20C)< 0.6 e hr
= 237 hr
Using the bimolecular reaction rate model, the half-life of Guthion at
pH 14 and 20 C was calculated to be less than 0.14 min, and the bimole-
cular rate constant was calculated to be greater than 4.8 l/(mole-min).
For the 2 lb/gal formulation, it was also determined that the time
required to degrade 99.9 percent of the Guthion with a IN NaOH solution
was approximately 2 min, when the volume-to-volume ratio of the IN NaOH
decontaminant solution to the Guthion formulation was five to one. In
general, these calculations have confirmed Chemagro's statement that
Guthion is very sensitive to alkaline hydrolysis and the reaction proceeds
40
rapidly at room temperature. Also, since the alkaline hydrolysis reac-
tion only takes place in the aqueous phase, it is recommended that ethanol
be added to make up a decontaminant solution of 50 percent ethanol in IN
NaOH, as Guthion has very low solubility in water.
The action of oxidizing agents on Guthion causes splitting off of
the thiono sulfur and formation of its oxygen analogue Gutoxon. As noted
from Table 16, Gutoxon is more rapidly hydrolyzed than Guthion under both
acid and alkaline conditions. In a IN NaOH solution, the principal pro-
ducts of Gutoxon hydrolysis would be anthranilic acid and the sodium salt
of dimethylthiophosphoric acid. Thus chemical oxidation followed by
alkaline treatment may be considered as an alternate detoxification
procedure for Guthion, although this leads to unnecessary complications
as Guthion is rapidly hydrolyzed by cold alkaline solutions.
For the decontamination of glass and metal containers for Guthion,
both the NACA triple rinse and drain procedure (Appendix D) and the pro-
cedure recommended by Chemagro may be considered. The Chemagro procedure
involves the use of a rinse solution containing caustic soda and
13
detergent. The quantity of the chemicals and rinse solutions recommended
as well as the proper decontamination procedure are described in detail in
Section 3.
63
-------
A. 7 CHEMICAL METHODS FOR THE DEGRADATION/DETOXIFICATION OF MALATHION
Malathion (0,0-dimethyl S-l ,2-dicarboethoxyethyl dithiophosphate)
IS & non-systemic insecticide with a wide range of agricultural and
horticultural uses. It is marketed in the form of 5 lb/gal emulsifiable
concentrates, 25 and 50 percent wettable powders, and 4 percent dust.
Malathion is miscible with most organic solvents though of limited
solubility in petroleum oils. Hydrolysis of malathion follows different
paths in acid and alkaline medium. In acid medium the main products of
hydrolysis are dimethylthiophosphoric acid and 2-mercaptodiethyl succinate,
while in alkaline medium the salt of dimethyldithiophosphoric acid and
14 21 22
diethyl fumarate are formed: ' '
S
H o H+ I
s 2 (ch3o)2poh + ch2cooc2h5
Js
(CH30)2PSCHC00C2H5
CH2C00C2H5
hschcooc2h5
Na0H » (CH302)2PSNa + CHC00C2H5
CHC00C2H5
Dimethylthiophosphoric and the sodium salt of dimethyldithiophosphoric
acid are not cholinesterase inhibiting materials and will undergo
further degradation to other nontoxic products. 2-Mercaptodiethyl
succinate has an oral LD5Q of 1156 mg/kg for rats and diethyl fumarate
has an oral LD5Q of 1780 mg/kg for rats. Although the 2-mercapoto-
diethyl succinate and diethyl fumarate formed are within the same range
of mammal ion toxicity as malathion, neither are cholinesterase inhibitors
and both compounds should be relatively nontoxic to insects and fish.
Thus, either acid or alkaline hydrolysis may be considered as acceptable
methods for the disposal of malathion.
The rate of hydrolysis of malathion has been extensively investigated.
Yost et al reported that malathion hydrolysis is almost instantaneous at
pH 12, whereas at pH 9 50 percent of malathion was hydrolyzed in 12 hr.^
42
At pH 5-7, however, no hydrolysis was observed over a period of 12 days.
64
-------
Ketelaar and Gersmann studied the alkaline hydrolysis of malathion and
derived an Arrhenius expression for the bimolecular reaction rate con-
stant. The activation energy was determined to be 24,500 cal/mole and
36
the bimolecular rate constant at 20 C was 154.5 l/(mole-min). Ruzlcka
et al found the half-life of malathion in a 20 percent ethanol-pH 6 buffer
15
solution at 70 C to be 7.8 hr. Konrad et al reported that malathion
hydrolysis did not occur in acid systems of pH>2, was slow at pH 9 (25
percent degradation in 7 days) and rapid at pH 11 (>99 percent in 1
43
day). Cowart et al found 59.3 percent malathion remaining after 7 days
30
in a neutral aqueous solution at room temperature. Malathion is
therefore resistant to hydrolysis in neutral or acidic solutions. In a
IN NaOH solution, however, the time required to degrade 99.9 percent
of the malathion in a 5 lb/gal formulation was calculated to be less than
a minute, when the volume-to-volume ratio of the decontaminant solution
to malathion formulation was ten to one. In practice, it is recommended
that a 50 percent ethanol-lN NaOH mixture be used as the decontaminant
solution, as the alkaline hydrolysis reaction only takes place in the
aqueous phase and the solubility of malathion in water is relatively low.
Wolverton et al have reported the use of a decontaminant solution
containing 25 percent monoethianolamine (MEA) in dipropylene glycol mono-
1 g
methyl ether (DPGME) solvent to detoxify malathion. For the decontami-
nation of malathion, 95 percent technical malathion was exposed to the
decontaminant solution in a volume-to-volume ratio of 10 parts decontami-
nant to one part malathion. Malathion was shown to degrade completely in
120 min. Also, data from the fish toxicity studies indicated that the
reaction product mixture is relatively nontoxic to fish, with a 48-hour
TLm of 2182 ppm for mosquito fish, as compared to malathion's 48-hour TLm
of 0.02 ppm for fish. In addition, it was shown that the detoxification
of malathion by MEA took place by a nucleophilic displacement reaction at
phosphorus, with a bimolecular reaction rate constant of 0.0160 l/(mole-min).
When malathion is oxidized by nitric acid or other strong oxidizing
agents the thiono sulfur atom is split off and the corresponding ester of
21
thiolophosphoric acid (malaoxon) is formed:
65
-------
s
(CH30)2!sCHC00C2H5 + 8 HN03
CH2C00C2H5
(CH30)2
'SCHCOOCgHg + 8 N02 + H2S04 + 3H20
ch2cooc2h5
Malaoxon is a cholinesterase inhibitor that is more toxic than malathion.17
Chemical oxidation is therefore not recommended as a disposal method for
malathion.
In a study conducted by Kennedy et al, malathion was treated with a
44
mixture of liquid ammonia and metallic sodium or lithium. In either
solutions 100 percent degradation of the malathion was obtained. However,
the chemical reagents used were dangerous and the identity and toxicity of
the reaction products were unknown. For these reasons, the liquid NH^-
Na or NH^-Li system cannot be considered in any practical disposal pro-
cedure.
For the decontamination of malathion containers, both the NACA
triple rinse and drain procedure (Appendix D) and the procedure recom-
mended by American Cyanamid may be considered. The American Cyanamid
procedure involves the use of a rinse solution containing caustic soda
and detergent and is similar to the procedure prescribed by Chemagro for
45
organophosphorus pesticides. The container decontamination procedure
is described in detail in Section 3.
66
-------
APPENDIX B
CHEMICAL METHODS FOR THE DEGRADATION/DETOXIFICATION
OF NITROGEN-CONTAINING PESTICIDES
B.l GENERAL REVIEW OF APPLICABLE DISPOSAL METHODS
The nitrogen-containing pesticides have been broadly classified Into
the following groups with representative pesticides from each group:
Carbamates, thiocarbamates and dithlocarbamates - carbaryl,
maneb
Amides, anil ides, imides, and hydrazides - alachlor, captan
t Ureas and uracils - diuron
Triazines - atrazine
Amines, nitro compounds, quaternary ammonium compounds -
pi cloram, trifluralin
Unlike the organophosphorus pesticides, the nitrogen-containing pesticide
subclasses are different from each other in chemical structures and in
decomposition chemistry. There are no chemical disposal methods with
universal applicability to the nitrogen-containing pesticides. The dis-
posal methods applicable to each subclass of nitrogen-containing pesticides
will be discussed along with the chemical degradation/detoxification methods
for the representative pesticide from each subclass.
B.2 CHEMICAL METHODS FOR THE DEGRADATION/DETOXIFICATION OF CARBARYL
Carbaryl (Sevin, naphthyl N-methylcarbamic acid) is a versatile
insecticide used to control pests of cotton, vegetables and fruit crops.
The common formulations include the 50 percent, 80 percent and 85 percent
wettable powders (Sevin 50 W, Sevin 80 Sprayable, and Sevin 85 Sprayable),
the 2 to 50 percent dusts, the 5 to 10 percent granules, the 1 to 2 lb/gal
emulsifiable concentrates, and the 4 lb/gal oil formulation (Sevin 4 Oil).
Carbaryl is highly soluble in organic solvents. In alkaline medium
carbaryl is hydrolyzed to 1-naphthol, methyl amine, and the alkaline
21
carbonate:
^ Pages 67, 68,
are blank
-------
OCONHCH-
2NaOH
+ CH3NH2 + Na2C03
1-Naphthol has an acute oral LDgg of 2590 mg/kg for rats. Methyl amine
has an acute oral LDKn of 2500 mg/kg for rats. However, 1-naphthol is
47
more toxic than carbaryl to young clams and fish. It is also known
that 1-naphthol is unstable in the alkaline environment of sea water and
47
degrades to carbon dioxide and numerous other products. The main
decomposition product is a precipitate containing a stable free radical
that is toxic to certain estuarine species. Therefore alkaline treatment
of carbaryl must be followed by burial of the reaction solution in a
location away from water supplies.
The alkaline hydrolysis of other esters of carbamic acid follows the
same path as carbaryl:
' «
ROCNR" + 2NaOH ROH + R'NR" + Na2C03
where the products are a hydroxy compound, an amine, and sodium carbonate.
The nature of these hydrolysis products is dependent on the R, R' and R"
groups. It is thus possible to produce several hydrolysis products of
various degrees and types of hazard. The applicability of alkali
treatment as a disposal method for carbamate pesticides must therefore
be assessed on an individual basis.
46
Carbaryl is known to be rapidly hydrolyzed in strong alkali. In
a study conducted by Karinen et al, the amount of carbaryl hydrolyzed by
sea water (at pH 8) in four days was found to be 44 percent at 17 C, 55
48
percent at 20 C, and 93 percent at 28 C. Aly and El-Dib investigated
the hydrolysis of carbaryl in NaOH solution and found the rate of
hydrolysis to be first order with respect to the hydroxyl ion concentra-
49
tion. The observed half-lives and the calculated bimolecular rate
70
-------
constants reported by Aly and El-Dib are given in Table 17, along with the
50
values reported by Wauchope and Hague in a later study. At 20 C, the
blmolecular rate constants for alkaline hydrolysis of carbaryl as calcu-
lated from the data of Karinen et al, Aly and El-Dib, and Wauchope and
Hague are 140, 152, and 195 1/(mole-min), respectively. These values are
in reasonably good agreement with each other. Using the bimolecular
reaction rate model, the time required to degrade 99.9 percent of the
carbaryl in a 4 lb/gal formulation with IN NaOH was calculated to be less
than a minute, when the volume-to-volume ratio of the NaOH decontaminant
solution to carbaryl formulation was ten to one. In practice, it is
again recommended to use a 50 percent ethanol - IN NaOH mixture as the
decontaminant solution, as the solubility of carbaryl in water is rela-
tively low. For the treatment of carbaryl manufacturing wastes, NACA
has recommended the addition of 2 lb of flake caustic (sodium hydroxide)
for each 5 lb of actual carbaryl and allow about 24 hours for completion
51
of the reaction. However, the amount of caustic recommended by NACA is
only approximately stoichiometric and at least a 50 percent excess should
be used. Also, the reaction time of 24 hours appears to be excessively
long.
Carbaryl is stable for weeks in weakly acidic solutions. Kennedy et
al reported that hydrogen peroxide treatment had no significant effect on
carbaryl.52 Nitric acid treatment, on the other hand, was found to induce
changes in carbaryl and lead to the formation of nitrobenzene, along with
other unidentified products. In the study of the decomposition of carbaryl
in plants and animals, it has been established that oxidation is directed
21
primarily at the methyl group attached to the nitrogen atom:
OCONHCH3 oconhch2oh
06-^06
Also formed as metabolites are 4-hydroxy- and 5-hydroxynaphthyl N-methyl-
carbamates, which further breakdown with rupture of the aromatic ring.
However, the chemistry of the oxidation process as well as the identity
71
-------
TABLE 17
EFFECTS OF pH AND TEMPERATURE ON
THE HYDROLYSIS RATE OF CARBARYL
pH
Temperature
(C)
Half-life
Bimolecular
rate constant
l/(mole-min)
Activation
energy
(cal/mole)
Reference
8.0
17
115.2 hr
100
48
Karinen et al
8.0
20
84 hr
140
24,090
8.0
28
24 hr
460
10.954
3
32 min
24.2
10.954
13
11 min
69.1
Aly and E1-Dib49
10.954
23
3.8 min
204
16,900
10.954
33
1.4 min
537
10
12
99 min
70
10
25
20 min
340
10
35
8 min
900
50
Wauchope and Hague
9.8
25
27 min
430
19,390
9.5
25
58 min
380
9.2
25
116 min
380
9.0
25
173 min
400
-------
of the reaction products are not well known. Chemical oxidation there-
fore cannot be considered as a disposal method for carbaryl.
Under the influence of sunlight, the reversal reaction of carbaryl
CO
to 1-naphthol and methylisocynate (CHgN=C=0) has been found to take place.
Methylisocynate is a poisonous and highly reactive substance. Accordingly,
carbaryl should always be submitted to alkaline hydrolysis before disposal.
For the decontamination of carbaryl containers, both the NACA triple
rinse and drain procedure (Appendix D) and the use of a rinse solution
containing caustic soda and detergent may be considered. The latter pro-
cedure is described in detail in Section 3.
B.3 CHEMICAL METHODS FOR THE DEGRADATION/DETOXIFICATION OF MANEB
Maneb (manganese ethylenebisdithiocarbamate)and its related com-
pounds form the group of dithiocarbamate fungicides which are the most
widely used and most versatile of organic fungicides. The other important
fungicides in the dithiocarbamate group are zineb, nabam and ferbam.
Zineb and nabam are the zinc and disodium salts of ethylenebisdithiocarbamic
acid, whereas ferbam is the iron salt of dimethyldithiocarbamic acid.
54 55
The common formulations of maneb include the following: '
Dithane M-45 - a coordination product of zinc ion and manganese
ethylenebisdithiocarbamate containing 16 percent manganese ion,
2 percent zinc ion and 62 percent ethylenebisdithiocarbamate ion
Dithane M-22 Special - a wettable powder containing 80 percent
maneb and 20 percent inert ingredients including zinc sulfate
Manzate - an 80 percent maneb wettable powder
Manzate D - an 80 percent maneb wettable powder containing zinc
Tersan LSR turf fungicide - an 80 percent maneb wettable con-
taining zinc
73
-------
Thus all the maneb formulations are 80 percent wettable powders with or
without zinc. There is no practical solvent for maneb, although the com-
pound has very slight solubility in water and in some organics.
The hydrolysis of maneb in either acid or alkaline medium is a rather
complex, multi-step process. In the presence of strong acids, maneb
decomposes with the formation of ethylene diamine, carbon disulfide and
a manganese salt:^
S
II
CH2NHCS>. CMH
: Mn + H2S04
2 2
ch9nh(js Ch2nh2
2CS2 + MnSO^
In the presence of weak acids, however, the hydrolysis of maneb follows a
different path, leading to the formation of ethylene thiourea, hydrogen
56 57
sulfide, carbon disulfide and manganese hydroxide: '
ch2nhcs>. CH2NHv
| Mn + 2H20 - | C=S + H2S + CS?
CH2NHjjs CH2NH-
| + Mn(0H)2
In neutral pH or alkaline sultions, the initial organic product is ;
ethylenethiuram monosulfide, which catf polymerize to polyethylenethiuram
56 58 59
monosulfide or further hydrolyze to ethylene thiourea. ' ' Ethylene
25 59
diisothiocyanate and ethylene diamine have also been reported. '
Also, alkaline hydrolysis is accompanied by the evolution of carbon
56
disulfide, but not of hydrogen sulfide. Presumably under these conditi
the sulfide sulfur remains in solution, possibly as the alkaline sulfide,
and is later oxidized by atmospheric oxygen to the sulfate.
The ethylene thiourea formed under mildly acidic, neutral, or alka-
line conditions is of special concern because it has been shown to be
74
-------
carcinogenic to mammals.^ Hence all the derivatives of ethylenebis-
dithiocarbamic acid are potential sources of carcinogenic products when
subjected to hydrolysis except in strong acid solutions. Even the use of
a strong mineral acid to dispose of maneb, however, results in the forma-
tion of carbon disulfide, a gas which could produce an undesirable
explosive and toxicity hazard. Disposal of maneb by either acid or alka-
line hydrolysis is therefore not recommended.
In the oxidation of maneb, ethylenethiuram monosulfide has been
OC CO
identified as one of the products. * The ethylenethiuram monosulfide
formed may again be further hydrolyzed to ethylene thiourea. Chemical
oxidation is therefore not considered as a disposal method for maneb.
For the disposal of small quantities of maneb formulations, burial
at least 18 inches deep in non-crop land away from water supplies is
recommended. The best method for the disposal of maneb (and other dithio-
carbamates) and maneb containers (usually in fiber drums or bags) is
incineration in a carefully-operated, well-designed incinerator. The
guidelines for maneb disposal by incineration are presented in the Rohm
54
and Haas Pesticide Disposal Manual.
B.4 CHEMICAL METHODS FOR THE DEGRADATION/DETOXIFICATION OF ALACHLOR
A1achlor (Lasso, 2-ch1oro-N-(2,6-diethylphenyl)-N-methoxymethylaceta-
mide) is a selective pre-emergence herbicide for the control of annual
grasses and broad-leaved weeds in crops. The usual formulations are the
15 percent granules.
Alachlor is slightly soluble in water. It is hydrolyzed under
strongly acid or alkaline conditions to form a secondary amine and gly-
col! i c acid:^5' ^
75
-------
In the application of alachlor at herbicidal dosage, the reaction products
obtained from its decomposition in the soil are the same as the hydrolysis
products and neither the secondary amine nor the glycol lie acid is toxic
to plants in the amounts released.^ Glycol lie acid has an oral LDKn
32
of 3200 mg/kg for rats and is therefore relatively nontoxic to mammals.
However, the secondary amine product is of concern because it could con-
ceivably react with nitrites in the soil to form a nitrosoamine, a suspected
carcinogen:
ch3och2nh ch3och2n-n=o
H5C2~"|^Jj~~C2H5 + NaN02 + HC1 H5Cr^j[""~C2H5 + NaC1 + H2°
At high application rates, CDAA (Randox), a chloroacetamide herbicide
similar to alachlor, has been found to inhibit the transformation of nitrite
to nitrate in soil, although at herbicidal dosage this is not significant.^1
The inhibition mechanism could be due to the reaction of the secondary
amine from CDAA hydrolysis with the nitrite to form nitrosoamines.
Lawless et al recently indicated a different set of hydrolysis products
from the treatment of alachlor by strong acid or alkaline solutions, where
chloroacetic acid, methanol, formaldehyde and 2,6-diethylaniline were
obtained.1 The chloroacetic acid would lead to glycollie acid under further
hydrolysis, and the 2,6-diethylaniline, being a primary amine, would not
form nitrosoamines with nitrites. 2,6-Diethylaniline has an oral LD^q of
2030 mg/kg for rats.^ However, since alachlor has a relatively low
mammalian toxicity and leads to soil decomposition products that are non-
toxic to plants when applied at herbicidal dosage, the recommended method
for the disposal of small quantities of alachlor is by landspreading at
herbicidal dosage. For the disposal of larger quantities of alachlor,
incineration should again be considered. For the decontamination of
alachlor containers, the NACA triple rinse and drain procedure (Appendix D)
is the only recommended method. The rinse solution should be disposed
of by addition to the spray tank.
76
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B.5 CHEMICAL METHODS FOR THE DEGRADATION/DETOXIFICATION OF CAPTAN
Captan (N-trichloromethylthiotetrahydrophthalimide) is a broad-
spectrum protective fungicide employed for the control of various diseases
of agricultural crops, including seed disinfection. It is marketed in the
form of 50 and 80 percent wettable powder, 5 and 10 percent dusts, and 25
to 75 percent dusts and wettable powder for seed treatment.
Captan is hydrolytically stable at neutral or acid pH but decomposes
fairly rapidly in alkaline media, resulting in the formation of tetra-
hydrophthalimide, hydrogen chloride, hydrogen sulfide,carbon dioxide, and
possibly elemental sulfur: '
+ 3HC1 + h2S + C02
21
Tetrahydrophthalimide is capable of further hydrolysis to phthalic acid.
In the presence of strong alkaline solution such as NaOH, sodium chloride,
sodium sulfide and sodium carbonate will be formed. Thus the alkaline
treatment of captan leads to the formation of nontoxic degradation products
and may be considered as an environmentally acceptable disposal method.
Daines et al reported that lime completely destroyed the fungicidal
62
activity of captan. Laboratory studies conducted on an aqueous slurry
of captan indicated that the rate of captan decomposition was very rapid
at pH 10.6 and instantaneous at pH 14. For the treatment of large spills
associated with captan or equipment decontamination, StaUffer recommends
the use of an aqueous solution of commercial low-foaming, hard water
detergent (Tide, Cheer, etc) in 5 percent trisodium phosphate or 10 to 25
percent sodium hydroxide.63 Captan is usually packed in 2 lb to 50 lb
bags. The empty bags should be buried in an isolated area away from
water supplies.
I H?0
dc>scci3 OyH
77
-------
Depending on whether hydrogen sulfide or elemental sulfur is formed
from the hydrolysis of captan, 3 to 4 moles of NaOH will be required to
neutralize the hydrolysis products from one mole of captan. For the
detoxification of 1 lb of 80 percent captan wettable powder, 1 gal of 10
percent NaOH is recommended. The amount of NaOH recommended is approxi-
mately 50 percent in excess of the stoichiometric requirement. The amount
of 10 percent NaOH necessary for the detoxification of captan formulations
of other concentrations can be estimated in a similar manner.
B.6 CHEMICAL METHODS FOR THE DEGRADATION/DETOXIFICATION OF DIURON
Diuron (N-3,4-dichlorophenyl-N',N1-dimethylurea) is an herbicide
mainly used for general weed control on non-crop areas and for selective
control of weed seedlings in certain crops. The usual formulations of
.. 64
diuron are:
Karmax diuron weed killer - a wettable powder containing 80
percent duiron
Karmax DL diuron weed killer - a water suspansion containing
28 percent diuron (2.8 lb diuron per gallon)
Krovar I weed killer - a wettable powder containing 40 percent
diuron and 40 percent bromacil
Krovar II weed killer - a wettable powder containing 27
percent diuron and 53 percent bromacil
Diuron is stable toward oxidation and moisture under ordinary con-
ditions. The rate of hydrolysis is negligible at ambient temperatures and
at neutral pH, but boiling with solutions of caustic alkalies or mineral
acids in water causes diuron to break dow.n with the formation of
21
3,4-dichloroaniline and dimethylamine or their salts:
0
CI
CI
78
-------
3,4-Dichloroani1ine has an oral LD5q of 740 mg/kg for mouse and dimethyl-
ami ne has an oral LDgg of 698 mg/kg for rats.^ By comparison, diuron
has an oral LD^q of 3400 mg/kg for rats. Thus the hydrolysis products of
diuron have higher mammalian toxicity than the starting material and
hydrolysis cannot be considered as a safe disposal method for diuron.
Similarly, the other substituted ureas, such as fenuron, monuron and
neburon, all result in dialkylamine and aniline or chloroaniline as hy-
21
drolysis products upon prolonged boiling with alkalies or mineral acids.
Chemical hydrolysis is therefore not recommended as a disposal method for
the substituted urea herbicides.
Diuron is persistent in soil and may remain effective for several
25
years as it is extremely resistant to attack by microorganisms. Diuron
wastes must therefore be disposed with great care to prevent unwanted
sterilization of soils. For the disposal of diuron wastes, proper incin-
eration is the only recommended procedure, although the disposal of small
quantities of diuron by burial in non-crop land away from water supplies
may also be considered. For the decontamination of diuron containers,
the NACA triple rinse and drain procedure (Appendix D) is the only recom-
mended method.
B.7 CHEMICAL METHODS FOR THE DEGRADATION/DETOXIFICATION OF ATRAZINE
Atrazine (2-chloro-4-ethylamino-6-isopropylamino-5-triazine) is used
as a selective pre-emergence and post-emergence herbicide on many crops
including maize, sorghum, sugar cane, pineapple, nursery conifers and for
general weed control. The usual formulations include the 50 percent
wettable powders (Gesaprim 80 and Primatol A 80).
Atrazine is stable in neutral, slightly acidic or alkaline media.
In the presence of strong alkali or mineral acids, and especially at
21 25 66
higher temperatures, atrazine is hydrolyzed to hydroxyatrazine: ' '
+ HC1
79
-------
Hydroxyatrazine is herbicidally inactive and will further decompose in
25
plants to amines and carbon dioxide. Since atrazine is biologically
Very Inactive apart from its herbicidal activity, the transformation of
atrazine to hydroxyatrazine is an effective detoxification process.
Armstrong et al reported that atrazine hydrolysis followed first-
order kinetics with respect to atrazine concentration at constant pH, but
that the rate of hydrolysis was also both acid and base catalyzed.66
Alkaline hydrolysis was suggested to involve direct nucleophilic displace-
ment of the -CI by -OH, and acid hydrolysis probably results from protona-
tion of a ring or chain N atom followed by cleavage of the C-Cl bond by
H,0. The activation energy for the degradation reaction was reported by
66
Zimdahl et al to be 10.8 kcal/mole. However, it is not clear from the
information provided whether this activation energy is applicable to acid
or base catalysis. Utilizing the pH dependent rate constant relationships
developed by Armstrong et al and assuming 10.8 kcal/mole as the activation
energy for both acid and base catalysis (even though this is not strictly
valid), the half-lives of atrazine at different pH values and temperatures
have been calculated and the results of these computations are presented
in Table 18. It is seen that atrazine detoxification should be conducted
in strong acids or alkalies and preferably at higher temperatures.
The National Agricultural Chemicals Association indicated that acid
or alkaline hydrolysis is an effective way of treating aqueous effluents
51
from the manufacturing and formulation processes for triazine herbicides.
The detoxification process recommended involves adjusting of the pH of the
aqueous waste to 1, followed by passing the solution through a hot water
heater and then discharging into a holding pond. The concentration of the
herbicide in the holding pond should be monitored to determine when it is
safe to discharge the solution to the sewer. The same procedure should
also be applicable to the disposal of atrazine formulations. However,
since alkaline hydrolysis of atrazine is more rapid than acid hydrolysis,
it is recommended that the detoxification process be carried out at pH 14.
For the detoxification of 1 lb of 80 percent atrazine wettable powder,
a minimum of 0.3 gal of 10 percent NaOH is recommended. This amount of
80
-------
TABLE 18
EFFECTS OF pH AND TEMPERATURE ON
THE HYDROLYSIS RATE OF ATRAZINE
Temperature
(C) Half-life
1
25
80 hr
1
40
33 hr
1
60
11.7 hr
1
80
4.7 hr
2
25
331 hr
3
25
1381 hr
12
25
295 hr
13
25
36 hr
14
25
4.5 hr
14
40
1.9 hr
14
60
40 min
14
80
16 min
81
-------
NaOH is necessary to assure a pH 14 in the reaction solution after part
of the NaOH is utilized to neutralize the HC1 formed from atrazine
hydrolysis, the amount of 10 percent NaOH recommended for the detoxifi-
cation of atrazine formulations of other concentrations can be estimated
in a similar manner. As noted previously, the alkaline treatment of
atrazine is preferably carried out at higher temperatures to facilitate
the rate of degradation.
The atrazine wettable powders are normally packed in bags. The
empty bags should be buried in an isolated area away from water supplies.
Chemical detoxification utilizing either acid or alkaline hydrolysis
is also applicable, to simazine and propazine. Both simazine and propazine
decompose into herbicidally inactive hydroxy derivatives and their rates
of hydrolysis in acid and alkaline solutions are similar to that of
21, 25, 51
atrazine.
B.8 CHEMICAL METHODS FOR THE DEGRADATION/DETOXIFICATION OF PICLORAM
Picloram (Tordon, 3,5,6-trichloro-4-aminopicolinic acid) is a growth
regular type herbicide used for the control of perennial and annual weeds.
The amine and potassium salts of the acid are highly soluble in water and
normally used in the pesticide formulations. The common formulations of
i i . 67,68
picloram include: '
Tordon 22K weed killer - a liquid containing 24.9 percent of
the potassium salt of picloram (2 lb acid equivalent per
gallon) and 75.1 percent isopropanol, water and dispersing
agents.
Tordon 101 Mixture weed and bush killer - a liquid containing
10.2 percent of the trisopropanolamine salt of picloram
(0.54 lb acid equivalent per gallon), 39.6 percent of the
trisopanolamine salt of 2,4-D (2.0 lb acid equivalent per
gallon) and 50.2 percent sequestering agents, water and
isopropanol.
82
-------
Information on potential chemical detoxification methods for picloram
is sparse. Kennedy et al reported that treatment by hydrogen peroxide
(5, 15 and 30 percent), nitric acid (4N, 8N, and 16N), sulfuric acid (9N,
18N, and 36N), and ammonium hydroxide (5N, 7.5N, and 15N) had no sign1f1 -
sodium hydroxide (2N, 4N, and 8N), however, picloram was decarboxylated
and the chlorine present was replaced by an OH group. Since 3, 5-dichloro-
4-amino-6-hydroxypicolinic acid has been isolated as a metabolite in
wheat and the 6- position is expected to be more reactive than the 3- and
5- positions, it is probable that the initial reaction in sodium hydroxide
also occurs at the 6- position:^
The extent of dehalogenation of piclorams in the sodium hydroxide solution
was not given by Kennedy et al. The reaction products may therefore be a
mixture of 3,5-dichloro-6-hydroxy-4-aminopyridine, 3-chloro-5,6-dihydroxy-
4-aminopyridine, 5-chloro-3,6-dihydroxy-4-aminopyridine, and 3,5,6-
trihydroxy-4-aminopyridine. The toxicity and the herbicidal activity of
these products are not known at this point.
In a later study, Kennedy et al found that treatment with liquid
ammonia-metallic sodium or liquid ammonia-lithium caused 100 percent
44
degradation of picloram. Again, the identity and the toxicity of the
reaction products are not known. This chemical degradation process also
involves the handling of hazardous and highly reactive reagents and cannot
be recommended as a disposal method for picloram.
For spills or leaks involving picloram formulations, Dow recommends
absorption with inert materials such as sand followed by, burial of the
waste in non-crop land away from water supplies.Dow has no specific
cant effect on the potassium salt of picloram.
52
Upon treatment with
83
-------
chemical procedure for the disposal of picloram.^ For the disposal of
small quantities of picloram formulations, Lawless et al recommends the
precipitation of the free acid from its solution by the addition of a
mineral acid, followed by incineration of the picloram acid and disposal
of the dilute residual solution in an area where several years persistence
in the soil can be tolerated J This is probably the best disposal pro-
cedure based on present knowledge.
For the decontamination of picloram containers, the NACA triple
rinse and drain procedure (Appendix D) is the only recommended method.
B.9 CHEMICAL METHODS FOR THE DEGRADATION/DETOXIFICATION OF TRIFLURALIN
Trifluralin (Treflan, 2,6-dinitro-N,N-dipropyl-4-trifluoromethylani-
line) is a pre-emergence herbicide with little post-emergence activity for
the annual weeds in cotton, soybeans, and several other crops. The usual
formulations include a 4 lb/gal emulsifiable concentrate (Treflan EC) and
5 percent granules (Treflan 5G).
Trifluralin is resistant to oxidation and acid and alkaline hydrolysis.
Kennedy et al reported that treatment by hydrogen peroxide, nitric acid,
sulfuric acid, and sodium hydroxide had no significant effect on trifluralin,
52
talthough ammonium hydroxide treatment did result in a color change. On
the other hand, trifluralin has been known to be susceptible to photo-
chemical decomposition.71 Crosby and Leitis reported that photodecompo-
sition of trifluralin was rapid under acidic conditions, but above pH 7.4
72
the rate declined sharply and the product portions changed. 2-Amino-6-
nitro-4-trifluoromethylaniline (II) was found to be the principal product
under acidic conditions while 2-ethyl-5-nitro-7-trifluoromethylbenzimidazole
(III) was the principal product in base. A multitude of other degradation
products was also detected.
84
-------
CF
CF
CF
Tri fluralin
II
III
The major hydrolysis products of trifluralin would be identical to
those formed from photodecomposition at the same pH. These degradation
products are believed to be herbicidally inactive but their total environ-
mental effects, such as the toxicity to fish, are not known at present.
Elanco Products does not recommend any chemical degradation/
73
detoxification method for the disposal of trifluralin. The major en-
vironmental effect of concern in the disposal of trifluralin is its
toxicity to fish. Contamination of any body of water by disposal of
wastes or cleaning of equipment should therefore be avoided. Trifluralin
is known to be strongly adsorbed onto the soil and is resistant to move-
ment by water, and burial in specially designated landfills or isolated
areas away from water supplies is the procedure recommended by Elanco for
73
the disposal of small quantities of trifluralin. The best method of
disposal, of course, is to use trifluralin according to label directions.
For the decontamination of trifluralin containers, the NACA triple
73
rinse and drain procedure (Appendix D) is recommended. Rinse solutions
from containers can be poured into the spray tank for application. Trif-
luralin bags should be destroyed when empty and disposed of through
regular refuse collection system or buried in an isolated area away from
74
water supplies.
85
-------
APPENDIX C
CHEMICAL METHODS FOR THE DEGRADATION/DETOXIFICATION
OF HALOGEN-CONTAINING PESTICIDES
C.l GENERAL REVIEW OF APPLICABLE DISPOSAL METHODS
A number of chemical methods are potentially applicable for the
detoxification of the halogen-containing pesticides. It is well known
that DDT undergoes dehydrochlorination in alkaline solutions to DDE. The
use of zinc in ethanol or sodium iodide in acetone is effective in the
75
dehalogenation of 1,2-dihalides. Chau recently reported the reduction
of chlordene and heptachlor with prolonged boiling in an acetone solution
7fi
of chromous chloride. Dennis suggested the use of nickel boride to
replace the more expensive palladium on charcoal, raney nickel or cobalt
as a catalyst for dehalogenation.^ Kennedy et al showed that treatment
with liquid ammonia and metallic sodium or lithium caused complete degra-
44
dation of 2,4-D, DDT, dieldrin, dalapon, and 2,4,5-T. Several other
investigators have demonstrated that a metallic sodium-butanol , tetra-
hydrofuran (THF) system or lithium-butanol-THF system is equally effective
in leading to total dehalogenation.^
The major problem with the chemical dehalogenation methods described
above is that most of these methods involve the use of costly and specific
chemical reagents that are often hazardous. In addition, the extent of
dehalogenation, and hence the identity and environmental hazards of the
degradation products are almost always unknown. At the present time,
there are no practical chemical degradation/detoxification processes for
the disposal of halogen-containing pesticides. Alternate disposal methods
and more detailed decomposition chemistry of the specific pesticides will
be discussed in the following sections.
C.2 CHEMICAL METHODS FOR THE DEGRADATION/DETOXIFICATION OF METHOXYCHLOR
Methoxychlor (1,1,l-trichloro-2,2-bis [p-methoxyphenol] ethane) is
used for the control of a wide variety of insects attacking fruits,
vegetables, field and forage crops, and livestock, as well as certain
household and industrial insects. The usual formulation is a 50 percent
wettable powder (Marlate 50).
89
Pages 86, 87 and 88 are blank
-------
Methoxychlor is resistant to oxidation and similar to DDT in its
chemical properties. The dehydrochlorination of methoxychlor, however,
takes place considerably more slowly than DDT. Melnikov reported that
the rate constant of the reaction of DDT with KOH in alcohol at 40.19 C
was 192 times greater than that of the p,p'-isomer of methoxychlor at the
21
same temperature. Du Pont also indicated that alkali treatment of
78
methoxychlor is ineffective. In addition, the environmental hazards
of the alkaline hydrolysis degradation product, 1,1-dichloro-2,2-bis
(p-methoxyphenyl) ethylene, are not well known.
Methoxychlor is susceptible to catalytic dehydrochlorination by
3
heavy metal catalysts. However, the reaction conditions and the extent
of dehydrochlorination have not been investigated. The reaction product
is likely to be the diphenylethylene derivative identical to that obtained
from alkaline hydrolysis. Catalytic dehydrochlorination therefore cannot
be recommended as a disposal method.
Du Pont recommends incineration with scrubbing as the disposal method
78
for methoxychlor. For the disposal of small quantities of methoxychlor
and empty bags, burial in non-crop land away from water supplies is the
only practical and recommended method.
C.3 CHEMICAL METHODS FOR THE DEGRADATION/DETOXIFICATION OF CHLORDANE
Chlordane (1,2,4,5,6,7,8,8-octachloro-2,3,3a,4,7,7a-hexahydro-4,7-
methanoindene) is a broad spectrum insecticide for house and institution
use. The common formulations include solutions containing 20 to 50 per-
cent technical chlordane in deodorized kerosene and emulsifier, 25 to 40
79
percent wettable powders and dusts, and 5 to 3 percent granules.
Technical grade chlordane contains 60 to 75 percent of the cis- and
trans-isomers of chlordane, and 25 to 40 percent of related compounds,
21
including chlordene, heptachlor and nonachlor. Under the influence of
caustic alkalies, chlordane undergoes partial dehydrochlorination. The
cis-isomer (a-chlordane) is thought to be more readily dehydrochlorinated
than the trans-isomer (e-chlordane), but the splitting out of more than
90
-------
two chlorine atoms is not possible even for a-chlordane under ordinary
conditions.20 Bowery indicated that chlordane was dechlorinated by alkali
to yield nontoxic products.24 This statement was not verified by Velsicol.
Sweeny and Fischer demonstrated that chlordane could be substantially
degraded by the mildly acidic reduction of zinc powder or zinc-copper
on
couple. Melnlkov also reported that more than two chlorine atoms were
21
split out when chlordane was acted on by zinc dust 1n acid medium.
However, the degradation products were not Identified and the zinc 1ons
formed are toxic and pose another environmental problem. Z1nc reduction
is therefore not considered as an acceptable disposal method for chlordane.
In the analysis of chlordane formulations, the total chlorine content
is determined by converting all organically bound chlorine to chloride ion
by using a metallic sodium-lsopropyl alcohol solution and refluxing vlgor-
24
ously for 30 minutes. This again 1s not a practical disposal method.
Velsicol indicates that no practical chemical treatment 1s available
79
for chlordane at this time. The basic objection to the use of alkali
treatment is that several days to weeks contact time may be required to
insure complete hydrolysis. For the disposal of excess chlordane, Velsicol
recommends incineration at 1800 to 2000 F, with a residence time of a
minimum of one second. This is 1n agreement with the recommended inciner-
ation conditions from a recent TRW study on the thermal degradation of
81
chlorinated hydrocarbon pesticides. For the decontamination of chlor-
dane containers, the triple rinse and drain procedure developed by NACA
(Appendix D) is recommended. If correctly folloiwed, the rinsed containers
can be safely handled for disposal, recycling for metal, or drum recondi-
tioning.
C.4 CHEMICAL METHODS FOR THE DEGRADATION/DETOXIFICATION OF T0XAPHENE
Toxaphene is a complex mixture of polychlorinated camphenes containing
67 to 69 percent chlorine and has the approximate composition of C-|oH10^8*
It is a non-systemic and persistent contact and stomach insecticide.
Toxaphene is marketed as a 90 percent toxaphene - 10 percent solvent
91
-------
82
solution using mixed or modified xylene as the solvent. This solution
is then formulated by various companies into emulsifiable concentrates,
either alone or with other insecticides. Little or no toxaphene is cur-
rently being used in dust, wettable powder, or granule formulations.
Treatment by alkalies causes toxaphene to split out part of the
21
chlorine but does not lead to complete degradation. In laboratory
experiments conducted at Tenneco Chemicals, the dehydrochlorination of
toxaphene by refluxing one part with 100 parts of 2 percent alcoholic
potassium hydroxide removed 33 percent of the total chlorine in one half
OO
hour. The same reagent at room temperature removed 25 percent of the
chlorine in five hours. Tenneco indicated that there was evidence that
the dehydrochlorinated residue was less active biologically and less toxic
but the reaction product mixture has not been further characterized. In
a recent Russian study by Lyubenko et al, it was found that boiling toxa-
phene for six hours in water resulted in 98 percent degradation of
toxaphene, but the extent of dehydrochlorination was not specified and
83
may be minor.
In the analytical determination of toxaphene, several methods are
available for converting all organically bound chlorine to chloride ion.
These decomposition procedures include the reaction of toxaphene with
metallic sodium in isopropyl or isobutyl alcohol, metal-organic reagents
24
such as sodium biphenyl, and metallic sodium in liquid ammonia. None
of these can be considered as practical disposal methods.
For the disposal of small quantities of toxaphene, both Hercules and
Tenneco recommend either fuel assisted incineration or burial in a secure
landfill lined with an impervious material or naturally isolated from
82 83
groundwater. ' Alkali treatment is the chemical method that offers
the best possibilities but cannot be recommended because it does not lead
to complete detoxification.
A significant portion of the 90 percent toxaphene is delivered in
55 gallon lined drums. For the decontamination of these containers, the
92
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drums should be drained as completely as possible and then carefully rinsed
with repeated rotation. A triple rinse with about a gallon of solvent
(xylene or the safer mineral spirits, if compatible with the formulation)
83
is recommended by Tenneco. The rinse solution can be added to the next
formulation batch and the drum can be sent to a drum reconditioner for
restricted reuse. For the decontamination of containers for toxaphene
emulsifiable concentrates, the NACA triple rinse and drain procedure
(Appendix D) is recommended. The rinse solution can either be added to
the spray tank or buried in non-crop lands away from all possible contact .
with water supplies. The containers should either be sent to a drum
reconditioner or made useless by punching holes in them followed by burial
in landfill operations.
C.5 CHEMICAL METHODS FOR THE DEGRADATION/DETOXIFICATION OF 2,4-D
2,4-D (2,4-dichlorophenoxyacetic acid) and its salts and esters are
systemic herbicides widely used for the weeding of cereals and other crops.
2,4-D is not normally used in the free acid or sodium salt form because of
low solubility and limited herbicidal activity. The most common forms of
2,4-D are the dimethyl amine, ethanolamine, and mixed alkanolamine salts
and isopropyl, butyl, iso-octyl and propylene glycol butyl ether esters.
The amine salts are usually marketed as solutions of declared 2,4-D content
(e.g., Dow DMA-4 herbicide). The esters are usually formulated as emulsifi-
able concentrates (e.g., Esteron 99 Concentrate weed killer).
The free acid form of 2,4-D reacts with inorganic bases to form
stable salts and is resistant to further reaction. On prolonged boiling
with HBr or HC1, 2,4-D decomposes to 2,4-dichlorophenol and glycollic acid:
2,4-Dichlorophenol is also obtained by the chemical cleavage of the ether
84
bond when 2,4-D is fused with pyridine hydrochloride. 2,4-Dichlorophenol
93
-------
is an intermediate soil degradation product of 2,4-D and is extremely
QC Qg 07
susceptible to photodecomposition. ' ' However, neither method
described above for converting 2,4-D to the phenol is suitable as a
general disposai technique.
The NACA Waste Disposal Manual reported that chlorination of liquid
2,4-D waste by adding sodium hypochlorite solution or gaseous chlorine
at pH 3 and temperatures above 85 F for at least 10 minutes would render
51
the phenoxys nonherbicidal. The chlorination products were not identi-
fied. According to Melnikov, the chlorination of 2,4-D with gaseous
chlorine yields 2,4,6-trichlorophenoxyacetic acid, but at 200 to 205 C,
disintegration products are also found, including 2,4-dichlorophenol,
21
bis (2,4-dichlorophenoxy) methane, and others. When the ethyl ester
of 2,4-D is chlorinated at 195 to 210 C, the esters of 2,4-dichlorophenoxy-
chloro- and dichloroacetic acids and 2,4-dichlorophenyl chloromethyl ether
21
are obtained. Some of the same products are probably also obtained in
the chlorination of 2,4-D at pH 3. The environmental effects of these
products are not completely known. Chlorination therefore cannot be
recommended as a disposal method for 2,4-D at the present time.
Kennedy et al reported that hydrogen peroxide (5, 10 and 30 percent)
52
had no significant effect on 2,4-D. Melnikov indicated that the main
product of the nitration of 2,4-D by nitric acid or nitrating mixture is
2,4-dichloro-5-nitrophenoxyacetic acid with a small trace of 2,4-dichloro-
21
6-nitrophenoxyacetic acid: 0
HN0.
11
The toxicity and the environmental hazards of the nitration products are
unknown. Both nitration products may be herbicidally active. Nitration
is therefore not an acceptable disposal method.
94
-------
The use of metallic sodium or lithium in liquid ammonia to cause 100
44
percent degradation of 2,4-D has also been reported. The degradation
products were not identified. This again is not a practical disposal
method.
In summary, there are no practical chemical degradation/detoxification
methods for 2,4-D disposal. 2,4-D is known to be readily detoxified by
soil microorganisms and at low dosages is normally decomposed in one to
25
four weeks. The detection of 2,4-dichlorophenol, 4-chlorocatechol,
chloromuconic and succinic acids from either soil or pure culture studies
suggests a sequence of reactions involving ring hydroxylation and cleavage
or OC QO
and further metabolism of the open chain structure to carbon dioxide. ''
The non-persistence and detoxification of 2,4-D in soil indicate that burial
in non-crop areas away from water supplies would be an acceptable method
for the disposal of small quantities of 2,4-D.
Strong solutions of acid, amine or other salts of 2,4-D can be
precipitated with calcium or magnesium salts to reduce the quantity of
herbicides requiring disposal and minimizing the potential for water
51
contamination as a result of leaching. This technique is not applicable
to the 2,4-D esters.
Dow recommends incineration in a high temperature incinerator to
dispose of small amounts of unused 2,4-D.^ The recent TRW study recom-
mends incineration at temperatures above 1660 F for at least 0.3 seconds
81
for the complete degradation of 2,4-D esters. Incineration at high
temperatures with sufficient residence time leads to complete detoxifica-
tion of 2,4-D and is the most environmentally acceptable method for 2,4-D
disposal.
For the decontamination of 2,4-D containers, the NACA triple rinse
and drain procedure (Appendix D) is recommended. The small containers
should be punched full of holes, crushed and taken to a landfill. Large
containers (30 and 55 gallon drums) can be sent to a drum reclaimer or a
scrap metal dealer after rinsing according to the NACA procedure.
95
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C.6 CHEMICAL METHODS FOR THE DEGRADATION/DETOXIFICATION OF AMIBEN
Amiben (chloramben, 3-amino-2,5-dichlorobenzoic acid) is a selective
pre-emergence herbicide suggested for use on soybean, carrots and cucur-
bitaceous crops, and also on transplanted crops. The common formulations
include an aqueous solution of the ammonium salt containing 2 lb acid
equivalent/gallon (Amiben), a granule containing 10 percent acid equivalent
as the ammonium salt (Amiben Granular 10 percent), and 4 and 1.2 percent
granules as ornamental and garden weed killers.
Amiben is stable to heat, to oxidation, and to hydrolysis by acid or
3 20
alkaline media. ' Treatment by sodium hypochlorite rapidly decomposes
amiben. The chemistry of decomposition is unknown but probably involves
the generation of both mono- and dichloroamino compounds as the principal
products. The identity of these degradation products has not been con-
firmed and the environmental effects are completely unknown. The use of
sodium hypochlorite as a chemical reagent to detoxify amiben is considered
89
to be unacceptable by Amchem Products.
As,described in C.l, several chemical reducing agents, such
as the use of a combination of hydrazine and palladium charcoal, are
90
effective in dehalogenating the haloaromatic compounds. However, none
of these reagents can be considered in any practical disposal method.
Amiben is readily susceptible to photolysis by visible light. For
example, sunlight or a fluorescent sunlamp caused an aqueous solution to
become colored, probably as a result of polymerization process.^ Illumina-
tion by a lamp with a borosilicate glass filter has been reported to cause
69
rapid dechlorination at the 2-position. The reaction products from the
photodecomposition of amiben have not been completely characterized and it
is questionable whether photolysis can be considered as a practical method
for the disposal of small quantities of pesticides.
In summary, the use of chemical reagents as a means of amiben disposal
is not recommended at the present time. Amchem Products indicates that
amiben's shelf life is of sufficient duration to allow for total use of
96
-------
89
the product in accordance with label directions. On this basis, there
should be few instances of small quantities of excess amiben requiring
disposal.
For the decontamination of amiben containers, the NACA triple rinse
and drain procedure (Appendix D) is again recommended. The rinse solution
can either be added to the spray tank or buried in non-crop lands away
from water supplies.
C.7 CHEMICAL METHODS FOR THE DEGRADATION/DETOXIFICATION OF PENTACHLOROPHENOL
Pentachlorophenol (PCP) is an insecticide used for termite control and
the protection of cut timber from wood-boring insects and from fungal rots.
It is also strongly phytotoxic and hence used as a pre-harvest defoliant
and as a general herbicide. Pentachlorophenol is marketed in the form of
technical grade crystals, solution concentrates (e.g., Dowicide 7, pen-
chlorol, penta) or as sodium pentachlorophenate granules (Dowicide G,
Santaborite, Weedbeads). The technical grade crystals or solution concen-
trates are designed for use by large consumers for wood preservation. The
normal procedure is to dissolve or dilute pentachlorophenol to a 5 to 7
percent solution with petroleum solvents and impregnate the wood by pres-
91
sure treatment.
.21
Pentachlorophenol is decomposed by most, but not all, strong oxidizing
agents. For example, with nitric acid, tetrachloro-p-quinone (chloranil)
and tetrachloro-o-quinone are obtained:
OH 0
CI
CI,
cr
Cl
ci
C°]
HCl
Chloranil is a disinfectant that is stable to acids but reacts with alkalies
20
to form salts of chloranilic acid. Thus chemical oxidation of pentachloro-
phenol does not lead to complete detoxification.
97
-------
The chlorination of pentachlorophenol gives derivatives of cyclohexene
21
known as hexachlorophenols:
The hexachlorophenols are fungicidal and have been proposed for seed
disinfection. Chlorination is therefore not an acceptable disposal method.
Sodium pentachlorophenate is highly soluble in water and can be
converted to pentachlorophenol by the addition of a strong mineral acid.
The pentachlorophenol is practically insoluble in water and therefore
minimizes the potential for water contamination when buried in ground.
There are no practical chemical methods for pentachlorophenol detoxifica-
tion. The only method recommended for the disposal of small quantities of
pentachlorophenol is to bury the material in an approved and designated
91
landfill or in an isolated area away from water supplies.
The containers for the technical grade crystals and sodium penta-
chlorophenate are paper bags. These should be emptied as thoroughly as
possible and then buried in an approved and designated landfill or an
isolated area away from water supplies. The solution concentrates are
usually delivered in metal cans or drums. These should be rinsed three
times with fresh portions of the diluting solvent which is then added to
the dilute mixture for wood impregnation.
98
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APPENDIX D
NACA TRIPLE RINSE AND DRAIN PROCEDURE
The National Agricultural Chemicals Association (NACA) recommends the
following decontamination procedure for pesticide containers:
1. Empty container into spray tank. Then drain 1n vertical position
for 30 seconds.
2. Add a measured amount of rinse water (or the designated spray
carrier) so container is 1/4 to 1/5 full. For container size
less than 1 gallon, add an amount of rinse solution equal to
1/4 of the container volume. For a 1 gallon container, add 1
quart of rinse solution. For a 5 gallon container, add 1
gallon of rinse solution. For 30 and 55 gallon containers,
add 5 gallons of rinse solution.
3. Replace closure. Shake container or roll and tumble to get rinse
on all interior surfaces. Drain rinse solution into sprayer or
mix tank. Continue draining for 30 seconds after drops start.
4. Repeat the above steps for total of 3 rinses. 1 gallon and 5
gallon steel containers should be punctured before draining the
3rd rinse. It is recommended that the container be punctured
in the top near the front sprout to allow for complete drainage .
of the third rinse.
5. For 30 and 55 gallon steel containers, replace closures and
secure tightly and send the containers to an approved drum
reconditioner (check with State Department of Agriculture for
list) or recycle as scrap into a steel melting plant. For 1
gallon and 5 gallon steel containers, crush immediately and
recycle for scrap to a steel melting plant. For glass containers,
break or crush into large container (such as 55 gallon open
headed drum with cover) and recycle for scrap to a glass melting
plant. If the above preferred container disposal method cannot
be accomplished, the container should be crushed and buried at
an approved dump site. Do not reuse containers.
101
Pages 99 and 100 are blank
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Preceding page blank
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1316
109
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