Prepublication issue for FPA libraries
and State Solid Waste Management Agencies
. IDENTIFICATION AND DESCRIPTION
OF CHEMICAL DEACTIVATION/DETOXIFICATION METHODS
FOR THE SAFE DISPOSAL OF SELECTED PESTICIDES
This report (SW-165c) describes work performed
for the Office of Solid Waste under contract no. 68-01-4487
and is reproduced as received from the contractor.
The findings should be attributed to the contractor
and not to the Office of Solid Waste.
Copies will be available from the
National Technical Information Service
U.S. Department of Commerce
Springfield, Virginia 22161
U.S. ENVIRONMENTAL PROTECTION AGENCY
1978
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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
Environmental Protection Agency, nor does mention of trade names or
commercial products constitute endorsement or recommendation for use.
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
information and Syracuse Research Corporation does not assume any
responsibility in connection with any accidents or injuries which may
result from using the detoxification procedures prescribed in this
report.
An environmental protection publication (SW-165c) in the solid
waste management series.
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AIJSTKACT
This .sc'c|in.'J ID Llic H;iiKlJ>ook. for Pesticide Disposal by Common Uii-nii c'.'i I
Methods has examined chemical detoxification/degradation methods for 40 pesti-
cides. The objectives for this study are the same as described in the compan-
ion: to develop practical chemical methods by which the layman can detoxify
pesticides and to delineate hazards associated with the detoxification methods.
The 40 pesticides were selected on the basis of their toxicological properties,
their consumption, and their representation of other pesticides. Chemistry
was reviewed for each through literature search and personal contacts with
pesticide manufacturers and other sources. Although many of the selected
pesticides are susceptible to alkaline hydrolysis, this approach is only
recommended for 11 of the pesticides: monocrotophos; phosphamidon; fensulfo-
thion; PennCap-M (microencapsulated methyl parathion); disulfoton; phorate;
methamidophos; carbofuran; aldicairb; methomyl; and captafol. Details for
treating each of the 11 pesticides are presented. No acceptable chemical
detoxification was found for the remaining pesticides: ronnel; dimethoate;
Dyfonate; Def; EPTC; molinate; thiram; propanil; Diphenamid; chloroxuron;
simazine; cyanazine; Amitrole; paraquat; PCNB; dinoseb; chloropicrin; chloro-
benzilate; endrin; D-D; dibromochloropropane (DBCP); BHC; dicamba; sodium
fluoroacetate (Compound 1080); creosote; and warfarin.
111
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TABLE OF CONTENTS
SUMMARY
1. INTRODUCTION
2. CLASSIFICATION AND SELECTION OF PESTICIDES
2.1 PRIORITIZATION SYSTEM FOR PESTICIDE SELECTION 3
2.2 CLASSIFICATION OF PESTICIDES 6
2.3 SELECTED PESTICIDES 6
3. CHEMICAL METHODS FOR THE DISPOSAL OF SELECTED PESTICIDES 21
4. CONCLUSIONS AND RECOMMENDATIONS 31
APPENDIX A - CHEMICAL METHODS FOR THE DEGRADATION/DETOXIFICATION OF
PHOSPHORUS-CONTAINING PESTICIDES 44
A.I GENERA], REV TEW 01' APPLICABLE DISPOSAL METHODS 44
A.2 CHEMICAL METHODS FOR DETOXIFICATION OF MONOCROTOPHOS 52
A.3 CHEMICAL METHODS FOR DETOXIFICATION OF PHOSPHAMIDON 57
A.4 CHEMICAL METHODS FOR DETOXIFICATION OF FENSULFOTHION 62
A.5 CHEMICAL METHODS FOR DETOXIFICATION OF RONNEL 67
A.6 CHEMICAL METHODS FOR DETOXIFICATION OF DIMETHOATE 68
A.7 CHEMICAL METHODS FOR DETOXIFICATION OF DISULFOTON 71
A.'8 CHEMICAL METHODS FOR DETOXIFICATION OF PHORATE 74
A.9 CHEMICAL METHODS FOR DETOXIFICATION OF MONITOR 78
A.10 CHEMICAL METHODS FOR DETOXIFICATION OF DEF 80
A.11 CHEMICAL METHODS FOR DETOXIFICATION .OF PENNCAP-M 82
A.12 CHEMICAL METHODS FOR DETOXIFICATION OF DYFONATE 86
APPENDIX B - CHEMICAL METHODS FOR THE DETOXIFICATION OF NITROGEN-
CONTAINING PESTICIDES 89
B.I GENERAL REVIEW OF APPLICABLE DISPOSAL METHODS 89
B.2 CHEMICAL METHODS FOR DETOXIFICATION OF CARBOFURAN 94
B.3 CHEMICAL METHODS FOR DETOXIFICATION OF ALDICARB 96
B.4 CHEMICAL METHODS FOR DETOXIFICATION OF METHOMYL 100
B.5 CHEMICAL METHODS FOR DETOXIFICATION OF EPTC 103
B.6 CHEMICAL METHODS FOR DETOXIFICATION OF MOLINATE 104
B.7 CHEMICAL METHODS FOR DETOXIFICATION OF THIRAM 105
B.8 CHEMICAL METHODS FOR DETOXIFICATION OF PROPANIL 107
B.9 CHEMICAL METHODS FOR DETOXIFICATION OF CAPTAFOL 108
B.10 CHEMICAL METHODS FOR DETOXIFICATION OF DIPHENAMID 111
B.ll CHEMICAL METHODS FOR DETOXIFICATION OF CHLOROXURON 112
B.12 CHEMICAL METHODS FOR DETOXIFICATION OF SIMAZINE 114
B.13 CHEMICAL METHODS FOR DETOXIFICATION OF CYANAZINE 116
B.14 CHEMICAL METHODS FOR DETOXIFICATION OF AMITROLE 118
iv
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TA1JLK OK CONTENTS (CONT'D)
Page
APPENDIX B (Cont'd)
B.15 CHEMICAL METHODS FOR DETOXIFICATION OF PARAQUAT 119
B.16 CHEMICAL METHODS FOR DETOXIFICATION OF PENTACHLORONITRO-
BENZENE (PCNB) 123
B.17 CHEMICAL METHODS FOR DETOXIFICATION OF DNBP (DINITRO-s-
BUTYLPHENOL) . 124
B.18 CHEMICAL METHODS FOR DETOXIFICATION OF CHLOROPICRIN 125
APPENDIX C - CHEMICAL METHODS FOR THE DETOXIFICATION OF HALOGEN-
i CONTAINING PESTICIDES ' 129
C.I GENERAL REVIEW OF APPLICABLE DISPOSAL METHODS 129
C.2 CHEMICAL METHODS FOR DETOXIFICATION OF CHLOROBENZILATE 132
C.3 CHEMICAL METHODS FOR DETOXIFICATION OF 2,4,5-T 134
C.4 CHEMICAL METHODS FOR DETOXIFICATION OF ENDRIN 137
C.5 CHEMICAL METHODS FOR DETOXIFICATION OF DIBROMOCHLOROPROPANE 140
C.6 CHEMICAL METHODS FOR DETOXIFICATION OF BHC (LINDANE) 143
C.7 CHEMICAL METHODS FOR DETOXIFICATION OF D-D 148
C.8 CHEMICAL METHODS FOR DETOXIFICATION OF DICAMBA 150
APPENDIX D - CHEMICAL METHODS FOR THE DETOXIFICATION OF INORGANIC
AND METALLO-ORGANIC PESTICIDES 151
D.I GENERAL REVIEW OF APPLICABLE DISPOSAL METHODS 151
D.2 CHEMICAL METHODS FOR DETOXIFICATION OF ARSENIC ACID 152
D.3 CHEMICAL METHODS FOR DETOXIFICATION OF MSMA (MONOSODIUM
METHANEARSONATE) 154
APPENDIX E - CHEMICAL METHODS FOR DETOXIFICATION OF MISCELLANEOUS
PESTICIDES 157
E.I GENERAL REVIEW OF APPLICABLE DISPOSAL METHODS 157
E.2 CHEMICAL METHODS FOR DETOXIFICATION OF SODIUM FLUOROACETATE 158
E.3 CHEMICAL METHODS FOR DETOXIFICATION OF CREOSOTE 160
E.4 CHEMICAL METHODS FOR DETOXIFICATION OF WARFARIN 163
APPENDIX F - PESTICIDE CONTAINER RINSE PROCEDURES 165
REFERENCES 171
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SUMMARY
This report is a sequel to the Handbook for Pesticide Disposal by Common
Chemical Methods (1). Its objectives are the same as the earlier report: to
develop chemical procedures which pesticide users could utilize for detoxify-
I
ing and deactivating waste pesticides and to delineate hazards associated
with the chemical methods of pesticide detoxification.
The study method was basically the same used in the earlier work (1).
Forty pesticides were chosen by similar criteria. The pesticides were selec-
ted based primarily upon criteria of domestic consumption, toxicity and
representative chemical classes. The selected pesticides were:
- Phosphorus-containing pesticides - monocrotophos, phosphamidon, fensulfo-
thion, ronnel, dimethoate, disulfoton, phorate, methamidophos, Def,
Dyfonate, and PennCap-M (microencapsulated methyl parathion).
- Nitrogen-containing pesticides - carbofuran, aldicarb, methomyl, EPTC,
molinate, thiram, propanil, captafol, Diphenamid, chloroxuron, simazine,
cyanazine, Amitrole, dinoseb, PCNB, and chloropicrin.
- Halogen-containing pesticides - chlorobenzilate, 2,4,5-T, endrin,
dibromochloropropane (DBCP), D-D, BHC (lindane), and dicamba.
- Inorganic and metallorganic pesticides - arsenic acid and MSMA.
- Miscellaneous pesticides - creosote, sodium fluoroacetate (Compound 1080)
and warfarin.
Information on chemical degradation and the toxicity of the degradation
products was collected by literature review, and contacts with pesticide manu-
facturers and research groups. The collected data was evaluated to identify
chemical reactions which convert the pesticides to non-toxic products. Then
criteria for acceptable reactions were assessed, which included availability,
safety, and cost of the reagents and equipment; reaction requirements such
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as temperature control; I lie technical ah 111 Lies needed for performance; and
react ion t ime.
Results and conclusions of this study generally agreed with the previous
study (1). Although many of the pesticides responded to alkaline hydrolysis
(which included the phosphorus-containing pesticides and some nitrogen-con-
taining and halogen-containing pesticides), alkaline hydrolysis was only
recommended for 11 pesticides: monocrotophos; phosphamidon; fensulfothion;
PennCap-M (microencapsulated methyl parathion); disulfoton; phorate; methami-
dophos; carbofuran; aldicarb; methomyl; and captafol. The hydrolytic detoxi-
fication procedure is detailed: it includes preparation of the caustic decon-
taminant; the quantity of decontaminant to use; directions for the decon-
tamination (e.g., method of mixing and contact time); and method for disposal
of the decontaminated waste. Also, a method for rinsing empty bottles and
drums with caustic decontaminant is described. Although the £-triazenes
simazine and cyanazine yield less hazardous products with alkaline hydrolysis,
because of their low solubilities and other factors an acceptable decontamina-
tion procedure by chemical reaction was not possible.
No simple chemical procedure was recommended for degrading the remaining
pesticides for one or more of the following reasons:
- Reaction conditions and requirements were beyond the capabilities of
the layman.
- Reagents were hazardous or expensive.
- Reaction rates were unknown or too slow.
- Degradation products were unknown, were toxic, or formed toxic products
in the environment.
vii
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Tlic- final rerommi'iKlal ions for I he 40 selected pest 1 c i.d«'s are snmmar i x.ed.
in Ta l>l.e 1.
Table 1. Chemical Disposal of the 40 Selected Pesticides
Do
Don't
Use alkaline hydrolysis:
Monocrotophos
Phosphamidon
Fensulfothion
PennCap-M (microencapsulated
methyl parathion)
Disulfoton
Phorate
Methamidophos
Carbofuran
Aldicarb
Methomy1
Captafol
Precautions:
Use personal protection
equipment. Follow disposal
procedure closely. Dispose
larger quantities in several
smaller batches.
Use chemical treatment:
Ronnel
Dimethoate
Dyfonate
Def
EPIC
Molinate
Thiram
Propanil
Diphenamid
Chloroxuron
Cyanazine
Simazine
Amitrole
Paraquat
PCNB
Dinoseb
Chloropicrin
Chlorobenzilate
2,4,5-T
Endrin
.... D-D
BHC (Lindane)
DBCP
Dicamba
Sodium Fluoroacetate
Creosote
Warfarin
Arsenic Acid
MSMA
vni
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1. INTRODUCTION
Tills study, Ldent JFic.Mtion and Description u£ Chemical Dcactivation/
DeLoxlf icat Ion Methods for tlie_S.'.i fc- Disposal of Pesticides, continues work
initiated in Handbook of Chemical Methods for Pesticide Disposal by Common
Chemical Methods (which for facilitation of discussion will be referred to as
the Handbook throughout this report) (1). Both the Handbook and this present
work have been sponsored by the Office of Solid Waste of the U.S. Environmental
Protection Agency. The purpose of both works was to develop information on
chemical methods for safely detoxifying selected pesticides. The Handbook,
which was authored by Shih and Dal Porto of TRW Systems, evaluated 20 pesti-
cides. This present study has followed the same general format as the Handbook
to evaluate an additional 40 pesticides.
The Handbook selected 20 pesticides by a process which was based, in
part, on numerical prioritization values and on chemical composition of the
pesticides. The selection process is discussed with greater detail in
Section 2. Shih and Dal Porto then gathered information in an extensive'
literature search and through personal contacts. They investigated chemical
methods to degrade the pesticides and sought toxicity data for the degradation
products. Where chemical methods rendered the pesticide non-toxic or yielded
significantly less hazardous products, they determined if an acceptable
procedure could be devised for the pesticide users who possess no technical
training. Shih and Dal Porto only judged alkaline hydrolysis as an acceptable
method for 7 of the 20 selected pesticides: naled; diazinon; guthion; mala-
thion; carbaryl; captan; and atrazine. The selected pesticides for which
they suggest alternative disposal methods include methyl parathion, dursban,
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man (2 h, aLachLor, diuron, picloratn, trLfluorulin, methoxychlor, 2,4-D, chlor-
dane, amibi-.n, and pt:nLaclilorophenol. Also, they have described handling and
disposal procedures for empty pesticide containers.
This present study has modeled its general study approach after the Handbook.
This report, like the Handbook, consists of four sections and extensive appendices..
The introduction and pesticide selection procedure are presented in Sections 1
and 2, respectively. Section 3 describes the suggested chemical detoxifica-
tion, container detoxification, and alternative disposal procedures. Section
4 summarizes conclusions and recommendations for pesticide chemistry and
disposal. The Appendices A, B, C, D, E, and F discuss phosphorus-containing
pesticides, nitrogen-containing pesticides, halogen-containing pesticides, in-
organic and metallo-organic pesticides, miscellaneous pesticides, and pesti-
cide containers, respectively.
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2. CLASSIFICATION AND SELECTION OF PESTICIDES ;
This study has selected pesticides for study by a modified version of the
Shih and Dal Porto method (1). A few were suggested by the Office of Solid
Waste of the Environmental Protection Agency because they were considered
disposal problems.
Although this study has selected a broader range of pesticide classifica-
tions than included in the Handbook, a large proportion was selected from among
the organophosphate esters and carbonyl-nitrogen bond containing pesticides.
Studies on chemical detoxification have recognized these classes as good can-
didates for deactivation by a chemical hydrolysis which appears suitable for
use by people with limited technical training (1-3).
2.1 PRIORITIZATION SYSTEM FOR PESTICIDE SELECTION
This study has quantitatively ranked pesticides by a modified version
of the Handbook's prioritization rating system. Shih and Dal Porto calculated
Prioritization Rating (PR) values by the relationship PR = Q-rf where r, and Q
were the toxicological hazard and the disposal quantity factors, respectively.
However, they discussed rankings as the logarithms (log PR) within the text. To
facilitate discussion this study has simplified the PR calculation: Q and r
are taken as logarithms of the numerical ratings assigned by Shih and Dal Porto,
so PR is calculated by addition:
PR = Q + r .
Table 2 defines the assignments of Q and r values. Seven hazard categories
were assessed: oral, inhalation, dermal, and aquatic toxicities; teratogeni-
city; mutagenicity; and carcinogenicity. The PR value was calculated from the
highest rf value in any one category. When several comparable pesticides
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Table 2. Prioritization Rating (PR) Factors: Q and r.
ST.P-
Annual Consumption
in
1.
2.
Metric Tons
(mm Ibs)
a
rf
Oral Toxicity
Inhalation
Toxicity
Q
3 . 2
>45,400 4,540-45,400
(>100) (10-100)
LD5Q <5 mg/kg LD5Q 5-50 mg/kg
LC5Q 1 50 ppm or LC5Q 50-200 ppm
^0.5 mg/1 or or U.5-2mg/l or
or r Value
1
454-4,540
(1-10)
LD5Q 50-500 mg/kg
LC50 200-2000 ppm
or OSHA 10-100 ppm
0
. <454
LD5() 500-5000 mg/kg
OSHA 100-1000 ppm
3.
4.
5.
6.
OSHA 1 ppm OSHA 1-10 ppm
Dermal Toxicity LD5Q <_ 20 mg/kg LD$Q 20-200 mg/kg Corrosive to skin
24 hr. skin contact 24 tir. skin contact
Aquatic Toxicity TL
m
mg/1
TL 1-10 mg/1 TL 10-100 mg/1
m m
Teratogenicity Known to be tera-
togenic
Carcinogenicity Known to be carcin-
ogenic
7. Mutagenicity Known to be mutagenic
Lachrymators
TL 100-1000 mg/1
m
Not known to be teratogenic
Not known to be carcinogenic
Not known to be mutagenic
rf is the highest value of r^exhibited by the pesticide in any hazard category.
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were assigned identical PR values, the individual toxicities were evaluated for
each pesticide. Tf further information on r assignment is wished, the Handbook
should be consulted. The prime sources for toxicological data were the Registry
of Toxic Effects of Chemical Substances (4) (referred to as the Registry) and
Water Quality Criteria 1972 (5). While the latter contained aquatic toxicity
data, the former is a compendium of information on the other toxicity categories.
The r values for oral, dermal, and inhalation toxicities used, when available,
values for rats as the common test organism. Where no rat data was available,
either data for an alternative organism was taken and/or other sources of tox-
icity data were accepted. The Registry also records positive tests for carcino-
gen fsis and teratogenesis; no positive mutagenic test was reported for any of
the selected pesticides. The r value of 3 was assigned to pesticides with
positive carcinogenic or teratogenic tests. The Registry lists feeding tests
in which neoplastic effects were identified; they were also assigned r
values of 3.
Since no quantitative data on pesticide disposal were available Shih
and Dal Porto estimated the disposal quantity factor, Q, from data on produc-
tion volumes. They tacitly assumed that disposal is directly related to
annual domestic production volume. Market data published in Stanford Research
Institute's Chemical Economics Handbook on consumption volume would better
estimate the disposal factor, Q (6). The marketing data are related by the
relationship
Consumption = Production + Import - Export
Some pesticides, such as paraquat and phosphamidon (Dimecron), are not even
domestically produced, but significant amounts (> 454 metric tons active
ingredients) are imported annually (2, 6).
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2.2 CLASSIFICATION OF PESTICIDES
Table 3 describes the pesticide classification scheme used in this
study. This scheme classifies pesticides according to chemical characteristics.
The Midwest Research Institute (MR!) originated this classification in their
report, Guidelines for the Disposal of Small Quantities^ of Unused Pesticides
(2). Shih and Dal Porto modified this classification scheme in the Handbook
(1). They excluded inorganic pesticides and reduced the number of categories
in the nitrogen-containing pesticide class and in the process grouped together
pesticides of different chemical reactivity. For example, they classed
together amines, nitro-compounds and quaternary ammonium compounds. The
pesticide classification system used in this report was better adapted to
select pesticides with a wide variety of chemical reactivity.
2.3 SELECTED PESTICIDES
The 40 selected pesticides are listed by their chemical classifica-
tion in Table 4. Tables 5 and 6 summarize salient toxicological information,
consumption data and calculated PR values. Table 7 reports ancillary infor-
mation on environmental persistence, mobility in soil and aqueous solubility.
i) Inorganic and Metallo-organic Pesticides
Only arsenicals were selected frpm this .classification. Over-
all arsenical consumption was estimated about 7.3 to 7.7 metric tons (16 to 17
million pounds); roughly two thirds were methylarsenic derivatives (6c). Mono-
sodium methanearsonate (MSMA) which has a PR value of 3 was selected to repre-
sent the methylarsonates (which includes DSMA, CAMA, and cacodylic acid).
Since it is the most highly consumed, arsenic acid (PR of 3) was also selected.
It typifies the other inorganic arsenic containing pesticides (such as calcium
and lead arsenate and sodium arsenite) .
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Table 3. Pesticide Classification System
Pesticide Classification
Typical Pesticides of Each Classi-
fication
I. Inorganic and organometallic
pesticides
1. Arsenic-containing compounds
2. Mercury-containing compounds
3. Other inorganics and metallo-
organics
II. Phosphorus-containing pesticides
1. Phosphates and phosphonates
Phosphorothioates and
phosphouothioates
Phosphorodithioates and
phosphonodithioates
Phosphorus-nitrogen compounds
Other phosphorus-containing
pesticides
4,
5.
III. Nitrogen-containing pesticides
1. Carbamates and related
compounds
2. Thiocarbamates
3. Dithiocarbamates
4. Anilides
5. Imides and Hydrazides
6. Amides
7. Ureas and Uracils
8. Triazenes
9. Heterocyclic amines
10. Nitre-compounds
11. Quaternary ammonium compounds
12. Other Nitrogen-containing
compounds
Arsenic trioxide, DSMA, Calcium
arsenate
Phenylmercuric acetate, Mercurous
chloride
DuTer (Triphenyl tin), Animate,
Copper, Sodium chlorate
Ciodrin, Dicrotophos, Monocrotophos,
Dichlorvos, Phosphamidon, TEPP
Abate, EPN, Fensulfothion, Fenthion,
Parathion, Ronnel
Carbophenathion, Dimethoate, Disul-
foton, Dyfonate, Phorate
Crufornate, Monitor
DEF, Folex
Carbaryl, Aldicarb, Baygon, BuxTen,
Carbofuran, Metacil, Methomyl
Diallate, EPIC, Mollinate, Pebulate
Amobam, Mancozeb, Polyram, Vapam
CDAA, Propachlor, Propanil
Folpet, Maleic hydrazide, Norbormide
Devrinol, Diphenamid
Chloroxuron, Diuron, Linuron, Monuron
Bladex, Pramitol, Simazine
Amitrol, DMTT, Mylone
Benefin, Dinoseb, PCNB
Diquat, Paraquat
Antu, Chloropicrin, Dodine
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Table 3. (Cont'd.)
Pesticide Classification Typical Pesticides of Each Classi-
f ication
IV. ll.i I o>;i'ii-con L;i i i) I ng pes I l.c Itlrs
.1. DDT related compounds Chlorobenzilate, Keltharie, Perthane
2. Chlorophenory compounds 2,4-D,2,4,5,T, Erbon, Silvex
3. Aldrin-Toxaphene group Aldrin, Dieldrin, Heptachlor, Kepone,
Toxaphene
A. Aliphatic and alicyclic BHC, Carbon tetrachloride, D-D,
chlorinated compounds Ethylene dichloride, Lindane
5. Aliphatic brominated compounds Dibromochloropropane, Ethylene dibromide,
Methyl bromide
6. Dihaloaromatic compounds Dicamba, Dichlorobenzene
7. Highly halogenated aromatic Dacthal, Pentachlorophenol, Tetra-
compounds chlorophenol
V. Miscellaneous pesticides
1. Sulfur containing pesticides Omite, Dexon, Sulfoxide
2. Botanical and Microbiological Rotenone, Strychnine, Pyrethrin
pes Lie: ides
'1. Organic pos t Ic i.dc-.s, not Acrolein, Carbon disulfide, Creosote,
elsewhere enumerated Kndothal, Warfarin, Sodium fluoroacetate
8
li
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Table 4. List of Selected Pesticides
Pesticide Class
Selected Pesticides
1. Phosphorus-Containing Pesticides
Phosphates and Phosphonates
Phosphorothioates and
Phosphonothioates
Phosphorodithioates and
Phosphonodithioates
Phosphorus-Nitrogen Compounds
Monocrotophos, Phosphamidon
Fensulfothion, Ronnel, PennCap-M
(microencapsulated methyl
parathion)
Dimethoate, Disulfoton, Dyfonate,
Phorate
Methamidophos
Other Phosphorus-Containing Pesticides Def
2. Nitrogen-Containing Pesticides
Carbamates
Thiocarbamates
Dithiocarbamates
Anilides
Imides and Hydrazides
Amides
Ureas and Uracils
Triazenes
Heterocyclic Amines
Quaternary Ammonium Compounds
Aromatic Nitro Compounds
3. Halogen-Containing Pesticides
DDT Related Compounds
Chlorophenoxy Compounds
Aldrin-Toxaphene Group
Aliphatic and Alicyclic Chlorinated
Compounds
Aliphatic Brominated Compounds
Dihalogenated Compounds
4. Inorganic and Organometallic Pesticides
Miscellaneous Pesticides
Carbofuran, Aldicarb, Methomyl
EPTC, Molinate
Thiram
Propanil
Captafol
Diphenamlde
Chloroxuron
Cyanazlne, Simazine
Amitrole
Paraquat
PCNB, Dinoseb
Chlorobenzilate
2,4,5-T
Endrin
D-D, BHC (Lindane)
DBCP
Dicamba
Arsenic Acid, MSMA
Sodium fluoroacetate, Creosote,
Warfarin
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Table '>. Consumption Volume and Hazard Properties ol: Llie
Selected Pest icides. Part I. ConsumpL ion Volume
I'esL icicle
MSMA
Arsenic acid
Monocrotophos
Phosphamidon
Fensulfothion
Ronnel
PennCap-M
Dimethoate
1) i su 1 foLan
Dy 1 ona t e
I'liorai e
Mon i 1 or
Del
Alclicarh
Carbof uran
Methomyl
Eptam (EPTC)
Molinate
Thiram
Propanil.
Captafol
Diphenamid
Chloroxuron
Bladex
Simazine
Amitrole
Dinoseb
Pentachloronitrobenzene (PCNB)
A
Annual ConsumpL i on 1
MM Pounds Metric Tons
9.4
6.0
4.2
1.5
4.2
1.1
—
2.3
5.6
3.6
7.7
O.H
6.5
2.7
13.4
5.3
6.4
2.7
0.7
9.0
4.0
2.5
1.0
7.3
7.8
1.4
6.2
2.3
4262.9
2721.0
1904.7
680.3
1904.7
498.9
—
1043.1
2539.6
1632.6
3492.0
362.8
2947.8
.1224.5
6076.9
2403.6
2902.4
1224.5
317.5
4081.5
1814.0
1133.8
453.5
3310.6
3537.3
634.9
.2811.7
1043.1
'roduc.L i on Ka I i nj» ,
Q
1
1
I
1
1
1
1
1
1
I
o
i
i
i
i
i
i
0
1
1
1
1
1
1
1
1
1
10
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Table 5. Consumption Volume and Hazard Properties of the
Selected Pesticides. Part 1. Consumption Volume (Cont'd.)
Pesticide
Paraquat
Chloropicrin
Chlorobenzilate
2,4,5-T
End r in
Benzene hexachloride (BHC)
D-D
Dibromochloropropane (DBCP)
Dicamba
Creosote
Warfarin
Sodium f luoroacetate
Annual Consumption Production Rating,
MM Pounds Metric Tons Q
1.6
7.8
1.0
6.7
1.2
1.0
56.5
22.4
2.8
1000.
12
<1
725.6
3537.3
453.5
3038.5
544.2
453.5
25,622.8
10,158.4
1269.8
453,500.
5422.0
. <453.5
1
1
1
1
1
1
2
2
1
3
2
0
Reference 6
11
-------
Table 6. Consumption Volume and Hazard Properties of the Selected
Pesticides. Part 2. Hazard Properties and Ratings.
Pest icide
MS MA
Arsenic acid
Monocrotophos
Phosphamidon
Fensulf othion
Ronnel
PennCap-M
(Methyl Parathion)
Dimethoate
Disulfotan
Dyf onate
Phorate
Monitor
Del"
Aldicarb
Carbof uran
Methomyl
EPTC
Molinate
Thiram
Propanil
Captafol
Diphenamid
Chloroxuron
Cyanazine
Simazine
Amitrol
Dinoseb
PCNB
Paraquat
Chloropicrin
Chlorobenzilate
2,4,5-T
a*
Acute Oral LD
(mg/kg) 3U
50b
48
21
17
2
906
>60
(9)
147, 30C
2d, 3.2e
3
1
7.5
150
L.O
llc, 5.3
17
1126, 1630
501
560
560
2500
293
10J, 3700
340
5000
1100
25
1650
57
250
700
300
Acute Dermal
LD5Qa* (mg/kg)
112
125
3
2000
1200f
(67)
353
6
147
3
118£
168
1400f
1100C, 120
1500
1460f
.-2000
10,000
80
80
a* **
Inhalation Toxicitv Aquatic Toxicity
(ppm) ' LC5Q (mg/t)
i.
4.5-100 (96 hrs)
0.305 (96 hrs)k
<1 (96 hrs) ,
0.063-3.7 (96 hrs)
i
0.0006 (96 hrs)
i
0.1 (96 hrs)
8.5 mg/cu m
200 mg/cu m (3 hrs)d 2.3 (96 hrs)1
0.3-4.5 (96 hrs)
i
16.0 (96 hrs)
0.8 (96 hrs)l
50-53 (48 hrs)
25 (48 hrs)k
i.
6.6 (48 hrs)
3.0-3.2 (48 hrs)
i
3.7-11 (48 hrs)
2400 mg/cu m/MC>
500 ppmb
Other •
Hazards *
u
Teratogenic
Teratogenic1
L
Carcinogenic
Teratogenic11
Carcinogenic
Teratogenic
Carcinogenic
Teratogenic
Hazard Priori:;, -tanking
Rating (r.) Value (r.. * 0)
i :
2 \
2 ;
3
3
3
3 -
3 -
3
3 -
2 2
3
3
3
i ;
: -,
3
3 i
i :
3
i :
2 3
i :
i :
3
3 i
3
3
3 -
3 -
3 i
-------
Table 6. Consumption Volume and Hazard Properties of the Selected
Pesticides. Part 2. Hazard Properties and Ratings (Cont'd).
Pesticide
Endrin
BHC
D-D
DBCP
Dicamba
Creosote
Warfarin
Sodium fluoro-
acetate
*
^Reference 4
Reference 5
- See Appendices
(a) For rats unl(
Acute Oral LD5Qa Acute Dermal
(mg/kg) "'so3* (mS/k§)
3 15
88,840C'
140 2100f
173 1400
1040
600d- 8
3-20QJ
0.22 . 20f
A-G for references
5ss otherwise specified
3* **
Inhalation Toxicity Aquatic Toxicity Other ^ Hazard
(ppzO LC.- (rag/t) Hazards Rating (r.)
50 I
0.0005-0.0012 (96 hrs)k h 3
Carcinogenic 3
1000 ppm (4 hrs) 1
103 ppm (8 hrs) Carcinogenic 2
20.0 (96 hrs) 1
0
3
300 mg/cu m (10 ain) Teratogenic 3
Priority
Value (rf
4
4
3
4
2
3
5
3
Ranking
+ Q)
(b) Unknown mammal
(c) Human
(d) LDLo or LCLo
(e) Wild Bird
(f) Rabbit
(g) Cat
(h) Mouse
(i) Hamster
(J) Dog
(k) Fish
(1) Crayfish
(m) Warfarin sodium
-------
Table 7. Soil Persistence, Soil Mobility and Water Solubility
of tlit1 Select oil Pesticides.
Pesticide
Soil
Persistence
(months)
Mob ili ty
Water Solubility
MSMA
Arsenic acid
Monocrotophos
Phosphamidon
Fensulfothion
Ronnel
PennCap-M
(Methyl Parathion)
Dimethoate
Disulfotan
Dyfonate
Phorate 1-3
Monitor
Def
Aldicarb
Carbofuran
Me thorny1
EPTC 1-3
Molinate
Thiram
Propanil
Captafol
Diphenamid
Chloroxuron
Cyanazine
Simazine 3-12
Amitrol
Dinoseb
PCNB
Paraquat
Chloropicrin
Chlorobenzilate
2,4,5-T . 3-12
Endrin >12
BHC >12
D-D
DBCP
Dicamba
Creosote
Warfarin
Sodium fluoroacetate
slightly mobile
slightly mobile
slightly mobile
mobile
immobile
soluble
167 g/£
miscible
miscible
1.6 g/fc
44 ppm
55-60 ppm
25-39 g/fc
25 ppm
13 ppm
50 ppm
90 g/£
insoluble
6 g/«.
700 ppm
58/S,
365 ppm
800 ppm
30 ppm
225 ppm
1 . 4 ppm
260 ppm
3 . 7 ppm
171 ppm
5 ppm
280 g/£
50 ppm
0.44 ppm
soluble
2.3
.
insoluble
278 ppm (free-acid)
soluble (amine salts)
insoluble
0.5-1.0 ppm
2
1
4.5 g/£
very slightly soluble
40 ppm (free acid)
soluble (Warfarin sodium)
very soluble
+ Reference 2
=¥ See Appendices A-C, for
-------
Other inorganic pesticides were eliminated either for reasons of
low consumption or no problem in disposal. Mercurials (inorganic and organic)
have a high environmental hazard but relatively low consumption. Although 0.9
to 1.4 metric tons (2 to 3 million pounds) were consumed, most was used in wood
preservatives or in paints (6c). Inorganic pesticides with high consumption but
no apparent disposal problem include sulfur, copper salts, sodium chlorate, and
ammate.
ii) Phosphorus-Containing Pesticides
a. Phosphates and Phosphonates :
Phosphamidon was chosen since it had the highest PR value of
4. Monocrotophos and ciodrin have PR values of 3. Both are phosphate esters of
(e)-3-hydroxycrotonamide; they differ only by the amide substituent. Monocroto-
phos was selected because of higher consumption and greater oral toxicity.
Dichlorovos (PR = 4) was not chosen since it can be degraded by the same proce-
dure recommended for naled in the Handbook (1).
b. Phosphorothioates and Phosphonothioates
PennCap-M, a microencapsulated formulation of methyl para-
thion, was selected. Although Shih and Dal Porto reviewed methyl parathion
disposal in the Handbook, information on the effect of microencapsulation on
product disposal was desired. Fensulfothion and ronnel (Korlan) were selected
since their PR values were 4.
c. Phosphorodithioates and Phosphonodithioates
Dimethoate, disulfoton, Dyfonate and phorate all received PR
values of 4. Since the four were judged good candidates for chemical deac-
tivation (2, 3) they were all selected. Before chemical deactivation could be
15
-------
recommended, the conditions of the chemical reactions had to be assessed, and
degradation products identified and their toxicities evaluated.
d. Phosphorus-Nitrogen Compounds
Methamidophos (Monitor) and cruformate both had PR values of
2. Monitor was chosen since its hazard rating was higher. Both, pesticides had
similar consumption volumes. While Monitor was slightly below Q-value cutoff
(363 metric tons), cruformate was slightly above (454 metric tons).
e. Other Phosphorus-Containing Pesticides
Def, a phosphorotrithioate, pesticide, was assigned a PR
value of 4. It was selected for study.
iii) Nitrogen-Containing Pesticides
a. Carbofuran (PR value of 5) and aldicarb (PR value of 4) were
selected since they had the highest PR values of the carbamates. Since the
carbamates are known Lo be susceptible to chemical degradation, another carbamate,
methomy1, was also selected. It was chosen over several other candidates with
PR values of 3 (Baygon, Buxten, chloropropham and metacil), because it was con-
sumed in significantly greater quantity.
b. Thiocarbamates
Molinate and EPIC (Eptam) were selected. Molinate received
a PR value of 4. EPIC and diallate both were assigned PR values of 3. EPIC
was chosen since its consumption is greater than ten times that of diallate.
c. Pi thiocarbamates
Several dithiocarbamates have displayed teratoge.nic effects
in feeding studies with rodents (4). Although the ethylene bisdithiocarbamate
pesticides are consumed in greater quantities than any other dichiocarbamates
16
-------
(6), they were not considered useful for study. Shin and Dal Porto rev lowed
chemistry for maneb, which will possess chemical reactivity characterislIc ol
all ethylene bisdlthiucarbamates. Thiram was selected as a representative for
this study since it was consumed in larger amounts than other candidate dithio-
carbamates (including CDEC and ziram).
d. Anilides
Propanil and propachlor both received PR values of 2. Al-
though the annual consumption for the two were similar (4,938 and 4,082 metric
tons for propachlor and propanil, respectively) (6), they were assigned differ-
ent Q values. Propachlor was slightly above cutoff, so it fell into the Q-value
2 range. Propanil was selected for study because it has a higher hazard rating.
e. Imides and Hydrazides
Three pesticides (maleic hydrazide, captafol, and folpet)
received PR values of 4. Captafol was selected since its known consumption was
highest (1814 metric tons). Folpet consumption, in comparison, was only 816
metric tons for the same year, 1974 (6). The SRI report did not list maleic
hydrazide consumption, since it is a plant growth regulator. The MRI study
estimated 1971 production at 1361 metric tons (2). !
f. Amides
A PR value of 2 was given to diphenamide. Since this was
the highest PR value of the group, it was selected.
g. Ureas and Uracils
Chloroxuron and monuron were assigned PR values of 3.
Chloroxuron was selected since its consumption was greater (454 versus 91
metric tons).
17
-------
li. Tr Lax. i nes
Shi.li ;mcl l);i 1 I'orlo suggest that the LriazLnes liave good
poll-lit ia.l for chemical degradation (I). Cyanazine (Bladex) and simazine both
were chosen since they are consumed in moderate quantities (approximately 3,300-
3,500 metric tons for 1974). Cyanazine has a relatively high oral toxicity
(LD „ of 340 for rats) among triazene herbicides. Simazine's hazard results
from its moderate aquatic toxicity.
i. Heterocyclic Amines
Amitrole was the only member of this class selected. It was
assigned a PR value of 3.
j . Ni I: ro-Compounds
I'CNH ('I'r rr.-u-li lor) which had the lilglic.sl I'K value (<>(' A) lor
(his group was se I re U-.d. Dinoseh ;.md hem:I'in were assigned I'K values of 3.
Dinoseb was selected since it was consumed by almost five-fold more than benefin
in 1974 (6c).
k. Quaternary Ammonium Compounds
Paraquat was assigned the highest PR value, 5. The only
other QAC with a moderate PR value was diquat, which received a value of 3.
However, its consumption was less than 100 metric tons in 1974.
1. Other Nitrogen-Containing Compounds
Chloropicrin was selected because of its PR value of 4.
iv) Halogen-Containing Pesticides
a. DDT-related Pesticides
Chlorobenzilate which received a PR value of 4 was the only
DDT analog chosen, since it was the highest of this class. Kelthane was assigned
a PR value of 3.
18
-------
b. Chlorophenoxy Compounds
Both 2,4,5-T and silvex were assigned PR values of 4.
2,4,5-T was selected because of higher consumption (3039 versus 907 metric tons).
c. Aldrin-Toxaphene Group
Aldrin, dieldrin, endrin, endosulfan, and heptachlor were
all issued PR values of 4. Since they are expected to behave more or less
similarly in chemical treatments, endrin was chosen as the representative (2).
d. Aliphatic and Alicyclic Chlorinated Hydrocarbons
Dichloropropene-dichloropropane (D-D) and carbon tetra-
chloride both received PR values of 5. Both are fumigants which are liquid at
room temperature. D-D was selected. Carbon tetrachloride was not chosen, since
it is primarily an industrial chemical. Benzene hexachloride (BHC) and ethylene
dichloride were assigned PR values of 4. BHC was selected for study. Ethylene
dichlorlde was not selected since two other chlorinated hydrocarbons and one
brominated hydrocarbon, DBCP, were selected and they are expected to behave
similarly.
e. Aliphatic Brominated Compounds
Dibromochloropropane (DBCP) and methyl bromide were given PR
values of 4. Methyl bromide is a gas at ambient temperatures and usually.
handled in returnable containers (1). DBCP was selected. It is a liquid at
ambient temperature. Also, recent evidence has demonstrated that it causes
sterility in human males (7).
f. Dehaloaromatic Compounds
Although dichlorobenzene was assigned a PR value of 5 it was
not selected for study. Its hazard rating of 3 results from a positive test for
19
-------
carcinogenesis (4). It is heavily used (27,216 metric tons) as a fumigant,
mostly as the familiar household mothballs. It is not considered a disposal
problem (1). Dicamba, with a PR value of 3 was selected for study.
g. Highly Halogenated Aromatic Compounds
No pesticide of this class was selected since its members
(for example, tetrachloro- and trichlorophenol) are similar to pentachloro-
phenol. Pentachlorophenol was evaluated in the Handbook (1).
v) Other Pesticides
Included in this class are sulfur-containing pesticides, botan-
ical and microbiological pesticides, and "organic pesticides not elsewhere
enumerated." Since the highest PR value for a sulfur-containing pesticides was
1, none were selected for study. Rotenone and strychnine both were given PR
values of 3. Since their consumption is minor and they do not characterize
other pesticides, they were not included for study. Among the "organic pesti-
cides not included elsewhere" PR values were assigned as 5 for warfarin, 4 for
carbon disulfide, and 3 for sodium fluoroacetate, creosote, and endothal. Since
carbon disulfide is primarily an organic reagent, it was not selected. Sodium-
fluoroacetate and creosote were selected since their disposal are now of interest
to EPA. Warfarin was selected since it has a high PR value and the sodium salt,
warfarin sodium, gave a positive test for teratogenicity (4).
20
-------
3. CHEMICAL METHODS FOR THE DISPOSAL OF SELECTED PESTICIDES
Chemical methods to detoxify or deactivate the 40 selected pesticides
were reviewed and evaluated by similar procedures to those used in ihe com-
panion study, Handbook for Pesticide Disposal by Chemical Methods (1). This
has included literature search and personal contact with pesticide manufac-
turers and formulators and with research workers. The results and conclusions
of the review are summarized in Appendices A through E for the phosphorus-
containing, nitrogen-containing, halogen-containing, inorganic and organo-
metallic, and "miscellaneous" pesticides, respectively. Also, a review of
recent literature on the effectiveness of container rinsing for removing
residues from empty containers is presented in Appendix F.
Conclusions of the present study generally agree with the companion
report (1). Alkali in aqueous solution or aqueous ethanol solution was
suggested for decontaminating 11 pesticides: monocrotophos; phosphamidon;
fensulfothion; disulfoton; phorate; methamidophos; PennCap-M (microencapsul-
ated methyl parathion); carbofuran; aldicarb; methomyl; and captafol. Alka-
line solution is recognized as a relatively hazardous material, but other
caustic products, such as household oven cleaners, have comparable hazards.
This study recommends the same general approach to alkaline hydrolysis as
the Shih and Dal Porto report (1). Table 8 describes personal protection
equipment for alkaline decontamination. Table 9 summarizes the conditions for
decontamination of the selected pesticides. It includes decontaminant solution
composition, the amount of decontaminant to use, and the contact time for each
pesticide. The contact times were estimated from the time calculated for 99.9%
21
-------
Tab 11' H. IVrsonal I'roU'c I i on K<|u j piintn t l''<>r IVsl i c. ixli1
Disposal . Adapted I i- oin Shih .-UK! D.-.I I I'orio (I).
Tin1 di'ci in I am i ii.'inl solution rc'coiiiMii'iidi'il lor I In1 chemical. (U:Lox il IcaLi.uti ol
|K-sL i i1. ides and pesticide containers .in most easels is strong caustic that
can severely burn skin, eyes, or any body tissue. In addition, inhalation
and skin contact with the pesticides 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.
A. 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.
22
-------
Table 9 . Recommended Decontaminant Solution and Contact Time for the Chemical
Detoxification of Selected Pesticides.
NJ
Pesticide
Monocrotophos
(Azodrin)
Phosphamidon
(Dimecron)
Fensulfothion
(Dasanit)
Disulfoton
(Di-Syston)
Fonnu lat ion
3.2 Ib/gal WM
4.0 Ib/gal WM
SOZ WP
8 Ib/gal WM
10 Ib/gal WM
6 Ib/gal SC
152 Granular
10% Granular
10Z Dust
10Z Granular
SOZ Granular
2Z Granular
Decontaminant
Solution
10Z NaOH
10Z NaOH
10 Z NaOH
10Z NaOH
10% NaOH
SZ NaOH in
SOZ Aqueous Ethanol
or 10Z NaOH in
SOZ Aqueous Ethanol
5% NaOH in
50% Aqueous Ethanol
52 NaOH in
SOZ Aqueous Ethanol
52 NaOH in
SOZ Aqueous Ethanol
SZ NaOH in
SOZ Aqueous Ethanol
SZ NaOH in
50% Aqueous Ethanol
52 NaOH in .
Ratio of Decontaminant
Solution to Formulation
4:1 by volume
5:1 by volume
1 gal/lb
8 :1 by volume
10:1 by volume
12:1 by volume
6:1 by volume
1 quart/lb
1 quart/lb
1 quart/lb
2 quarts/lb
1 quart/lb
1 quart/lb
Contact
12 hours
12 hours
12 hours
1 hour
1 hour
4 hours
2 hours
12 hours
12 hours
12 hours
3 hours
3 hours
3 hours
Time
(overnight)
(overnight)
(overnight)
(overnight }
(overnight )
(overnight)
SOZ Aqueous Ethanol
-------
Table 9. Recommended Decontaminant Solution and Contact Time for the Chemical
Detoxification of Selected Pesticides (Cont'd).
Pesticide
Phorat e
(Thimet)
Methamidophos
(Monitor)
PennCap-M
(microencapsulated
methyl parathion)
Carbof uran
. (Furadan)
Aldicarb
(Temik)
Met homy 1
(Lannate, Nudrin)
Formulation
6 Ib/gal EC
4 Ib/gal
2 Ib/gal
4 Ib/gal F
10% Granular
15% Granular
5% or 10% Granular
1.8 Ib/gal F !
90% water sol;. dust
2, 5% dust
Decontaminant
Solution
10% NaOH in
50% Aqueous Ethanol
10% NaOH
5% NaOH in
50Z Aqueous Ethanol
10% NaOH in
50% Aqueous Ethanol
5% NaOH in
50% Aqueous Ethanol
10% NaOH in-
50% Aqueous Ethanol
10% NaOH in
50% Aqueous Ethanol
10% NaOH
10% NaOH
10% NaOH
Ratio of Decontaminant
Solution to Formulation
6:1 bv volume
8:1 by volume
8:1 by volume
10:1 by volume
2 quarts/lb
1 gal/lb
2 quarts/lb
5:1 by volume
1 stal/lb
1 quart /lb
Contact Time
15 minutes
15 minutes
12 hours (overnight)
30 minutes
2 hours
12 hours (overnight)
12 hours (overnight)
3 hours
12 hours (overnight)
12 hours (overnight)
-------
Table 9. Recommended Decontaminant Solution and Contact Time for the Chemical
Detoxification of Selected Pesticides (Cont'd).
Pesticide
Captafol
.. . , a
formulation
4 Ib/gal F
80% WP
Decontaminate
Solution
10 7. NaOH
in 50% Aqueous Ethanol
10% NaOH
Ratio of Decontaminant
Solution to Formulation
10:1 by volume
Igal/lb ,
Contact
Time
15 minutes
1 hour
EC - Emulsifiable
F - Flowable
SC - Spray Concentrate
WM - Water Miscible
WP - Wettable Powder
in 50% Aqueous Ethanol
-------
IM.-.SI icidc ili:)'ra.;raim l.e.s, and other unknown factors. The. discussion in I In-.
Appendices has used alkaline normality for calculating degradation t Lines. The
concentrations of 5% and 10% sodium hydroxide are slightly higher than 1 and 2N,
respectively. Table 10 summarizes the decontamination procedures suggested for
use with the recommendations of Table 9.
The pesticides not detoxified by chemical treatment must be disposed by
an acceptable alternative. The EPA has published recommended procedures for
pesticide disposal and storage (40 CFR 165) and criteria for solid waste dis-
posal facilities (40 CFR 257) (la, 7b). Since recommendations for alterna-
tive disposal procedures are beyond the scope of this present report, the
regional EPA or appropriate state authorities should be contacted for specjfie
information on acceptable, alternative disposal procedures.
Empty pesticide containers should also be disposed safely. The Environ-
mental Protection Agency has recommended specific procedures (7a). If possible,
containers should be triple rinsed using the procedure outlined in Table 11.
An alkaline rinse solution is recommended when pesticide residues can he
detoxified by hydrolysis. If the pesticide is not water soluble, the aqueous
alkiili might not be effective. Aqueous ethanolic caustic more effectively
detoxifies these pesticides (Appendix F). Pesticides which can use aqueous
caustic are monocrotophos, phorate, phosphamidon, methamidophos, and methomy.l.
PosLicides which should use--the aqueous-ethanolic caustic are fensulfothion,
di^u.itu^on, PennCap-M (encapsulated methyl parathion), carbofuran, aldicarb,
and capi-jfol. Table 12 describes the recommended procedure for the caustic
rinse,
26
-------
Table 10. Pesticide Disposal Procedure - Chemical Detoxification i
by Alkali Treatment. Adapted from Shih and Dal Porto (L).
Tills procedure is only applicable to the present study. Do not use this pro-
cedure for other pesticides since decomposition products are unknown and may
be harmful. The quantity of decontaminant solution to be used is given in
Table 9. 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 8).
f
2. Carefully mix water, ethanol (if recommended) and caustic soda
(lye) in a container to make up the recommended decontaminant
solution (Table 9). 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. To make up 1 gal of the 10% NaOH -
50% ethanol solution use 2 cups of caustic soda, 2 qts of ethanol
and 1-3/4 qts of water. Allow the solution to cool before any use.
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 9) 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 9 for the
recommended contact time for each pesticide formulation.
6. Carefully loosen closures to vent any pressure build-up. 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.
27
-------
TabJe 1.1. NACA Triple Rinse and Drain Procedure.
From Shih and D.'il Porto (1).
1. Empty container into spray tank. Then drain in vertical position for
30 seconds.
2. Add a measured amount of rinse water (or 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 con-
tainers, add 5 gallons of rinse solution.
3. Replace closure. Shake container or roll and tumble to gel: 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. One gallon and 5 gallon
.steel containers should be punctured before draining the 3rd rinse.
1't is recommended that the container be punctured in the top near the
front sprout to allow for complete drainage of the third rinse.
'). 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 melt-
ing 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.
28
-------
Table 12. Pesticide Container Decontamination Procedure
With Caustic Soda. Adapted from Shih and Dal Porto (1)
This procedure is only applicable to empty glass and metal containers. Do
not use this procedure for containers of other pesticides without consulting
the pesticide manufacturer or EPA personnel. The procedure is outlined as
follows:
1. Use personal protection equipment (Table 8).
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 detoxification procedure
described in Table 10.
3. Carefully add water (or 50% aqueous ethanol), detergent and
caustic soda (lye) and tighten the bungs and other closures.
The amount of rinse solution to be added depends on the con-
tainer size.
Container Caustic Soda
Size Water Detergent . (Lye)
Less than
5-gallon 1 pint 1 tablespoon
5-gallon 2 quarts 2 tablespoons 1/2 cup
15-gallon 1-1/2 gallons 1/4 cup 1/2 pound
30-gallon 3 gallons 1/2 cup 1 pound
55-gallon 5 gallons 1 cup 2 pounds
4. Rotate the container carefully to wet all inner surfaces with the
rinse solution.
5. Let the container stand 15 minutes with occasional agitation.
6. Remove all bungs and closures and bury the rinse solution at
least J.8 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 con-
tainers 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.
29
-------
After the container has received an appropriate rinse, large containers
(30 and 55 gallon drums) could be turned over to a drum reconditioner. Rinsed,
smaller containers can be land disposed as sanitary wastes. For information
on the disposal of all containers which cannot be rinsed, the regional EPA
office or the appropriate state authority should be contacted.
The container rinsate must also be disposed in a safe manner. According
to the EPA recommended procedures (7a), the rinsate should be used as a
diluent for preparing spray mixtures wherever possible. If the rinsate cannot
be used for dilution and cannot be chemically detoxified/deactivated, then its
disposal must follow a procedure acceptable for the pesticide active ingre-
dient. The EPA regional office or the appropriate state authority should be
contacted for further information.
30
-------
4. CONCLUSIONS AND RECOMMENDATIONS
Chemical methods for detoxification and deact.ivat ion have hern evaluated
for 40 pesticides. This study follows an EPA-sponsored companion work on
chemical detoxification methods for 20 pesticides (1). The study methods are
the same and conclusions are similar. Hydrolysis with alkaline decontaminant
solution is judged a practical method for detoxifying 11 pesticides of the
selected pesticides: monocrotophos; phosphamidon; fensulfothion; disulfoton;
phorate; methamidophos; PennCap-M (microencapsulated methyl parathion); carbo-
furan; aldicarb; methomyl; and captafol. Conditions for disposal of waste
pesticides and empty pesticide containers is discussed in Section 3. Table 13
summarizes the salient information on chemistry and the properties of the
hydrolysis products for these 11 pesticides.
Table 14 summarizes salient information on chemical reactivity and
products for the pesticides which have no suitable chemical detoxification:
ronnel; dimethoate; Dyfonate; Def; EPTC; molinate; thiram; propanil; Diphen-
amid; chloroxuron; simazine; cyanazine; Amitrole; paraquat; PCNB; DNBP; chloro-
picrin; chlorobenzilate; 2,4,5-T; endrin; DBCP; D-D; BHC; dicamba; MSMA;'
arsenic acid; sodium fluoroacetate; creosote; and warfarin. In general, one
or more of the following reasons were cited for rejected chemical treatment:
- Chemical degradation products are hazardous or suspected as hazardous.
- Chemical degradation products are not known.
- Chemical reagents are expensive or hazardous. '
- Chemical degradation requires advanced technical skills. '
- Time required for complete degradation is too long or unknown.
31
-------
Table 13. Summary of Effects of Chemical Treatment on Pesticides for
which Alkali Treatment is Recommended.
Pesticide
Chemical Treatment Degree of Degradation
Identity and Environmental Hazard'of
Degradation Products
Monocrotophos
(Azodrin)
Alkaline hydrolysis Complete degradation
Sodium iodide Unknown degradation rate
Alkaline salts of dimethylphosphate, ace:cr.= , -e::.yl-
amine, and carbon dioxide are non-toxic.
Desmethylmonocrotophos toxicity is unknivrr:, ':•-: i-. -i
not an acetylcholinesterase inhibitor. Methyl i.~clce
is slightly toxic.
Phosphamidon
(Dimecron)
Fensulfochion
(Dasanit)
Acid hydrolysis
Sodium iodide
Complete degradation
Unknown degradation rate
Alkaline hydrolysis Complete degradation
Chemical oxidation Complete degradation
Alkaline hydrolysis Complete degradation
Initial products are dimethylphosphate ar.d !•'.
a-chloroacetamide. The amide subsequently r.y
to dimethylamine, chloroacetone, and carbor. i
All final and intermediate products are ncr.-:
Desmethy Iphosphamidon toxicity is unkp.ovr., :u
an acetylcholinesterase inhibitor. Methyl ic
slightly toxic.
Initial products are alkaline salts of dine:.-.;
phate, chloride, and N,N-diethyl 3-hydroxyace
The amide subsequently hydrolyzes to the ;ia:
of glycolic acid and alkaline acetate salts. All
final and intermediate products are non-toxic.
The corresponding sulfone is as toxic.
Alkaline salts of dimethylphosphate and £-(=e:hyl-
sulfamoyl) phenol are non-toxic.
-------
Table 13. Summary of Effects of Chemical Treatment on Pesticides for
which Alkali Treatment is Recommended (Cont'd).
Pesticide
Chemical Treatment Degree of Degradation
Identity and Environmental Hazard of
Degradation Products
Me thatnidophos
(Monitor)
U)
U)
Disulfoton
(Di-Syston)
Phorate
(Thimet)
Acid hydrolysis Unknown degradation rate
Alkaline hydrolysis Complete degradation
Chemical oxidation
Alkaline hydrolysis
Acid hydrolysis
Alkaline hydrolysis
Acid hydrolysis
PennCap-M (Encapsulated Alkaline hydrolysis
methyl parathion)
Acid hydrolysis
Chemical reduction
Chemical oxidation
Complete degradation
Complete degradation
Slow degradation rate
Complete degradation
Complete degradation
Complete degradation
Slow degradation rate
Unknown degradation rate
Complete degradation
0,S-dimethylphosphorothiolc acid and ammonia are
expected to be less toxic than Monitor.
Methyl mercaptan is moderately toxic. Salts of
-0-methylphosphoramidoate are expected to be less
toxic than Monitor.
The only known product is the sulfoxide CHjSSCOJjCH^.
Alkaline salts of 0,0-dimethylphosphorothioic acid
i
and ethylthioethyl mercaptan are non-toxic.
Essentially the same products as alkaline hydrolysis.
Alkaline salts of 0,S-diethylphosphorodithioate,
formaldehyde, and ethyl mercaptan are non-toxic.
Essentially the same products as alkaline hydrolysis.
Alkaline salts of dimethylphosphorothiate are non-
toxic; £-nitrophenol is slightly toxic, but far less
toxic than methyl parathion.
Essentially the same products as alkaline hydrolysis.
0,0-dimethyl-0-p_-aminophenylphosphorothioate is non-toxic.
Intermediate product methyl paraoxon is more toxic than
methyl parathion. The oxon can hyiitolyze to dimethyl
phosphate and £-nitrophenol.
-------
Table 13. Summary of Effects of Chemical Treatment on Pesticides for
which Alkali Treatment is Recommended (Cont'd).
Pesticide
Chemical Treatment Degree of Degradation
Identity and Environmental Hazard of
Degradation Products
Carbofuran
(Furadan)
Aldicarb
(Temik)
Methomyl
(Lannate, Nudrin)
Captafol
Alkaline hydrolysis Complete degradation
Acid hydrolysis Slow reaction
Alkaline hydrolysis Complete degradation
Chemical oxidation Complete degradation
Alkaline hydrolysis Complete degradation
Alkaline hydrolysis Complete degradation
Carbonate and methylamine are non-toxic. The to:-:i>; i :;•"
of 2,2-dimethyl-2,3-dihydrobenzofuran-7-ol is i:-•;.-.o-—
but is expected to be of the same order as i-nash:'"!
which is non-coxic.
Essentially the same products as alkaline hydrolysis.
Carbonate, methylamine and £-methyl, S-thiorr.ethylrre-
pionaldehyde oxise are non-toxic. However, oxines are
suspected carcinogens.
Aldicarb sulfoxide is rapidly produced and in si:-1!;.-
oxidizes to aldicarb sulfone. Both the sulfoxi-c ar-
sulfone are more toxic and are hydrolyzed faster ir.ar.
aldicarb.
Carbonate, methylar.ine, and S-methyl-N-hydro.xyltr io-
acetamidate are non-toxic.
Hydrolysis products are not fungicidally active. Chlor-
ide and dichloroacetate are non-toxic and sulfide is
slightly toxic. Tetrahydrophthalimide is not an. acute
toxicant but it is teratogenic. Tetrahydrophthaliziae
slowly hydrolyzes in base to yield the non-toxic. :ycio-
hex-2-ene-l, 2-dicarboxylic acid.
Acid hydrolysis
Slow reaction
Essentially the same products as alkaline hvdrolvsis.
-------
Table 14. Summary of Effects of Chemical Treatment on Pesticides
for which No Chemical Treatment is Recommended.
Pesticide
Chemical Treacnenc
Degree of Degradation
Identity and Environmental. Hazard of
Degradation Produces
U)
Ui
Ronnel
(Korlan, Fcnchloro-
phos)
Dicethoato
(Cygon)
Weak alkaline hydrolysis Complete degradation
Strong alkaline hydrolysis Complete degradation
Dyfonate
Def
Alkaline hydrolysis,
Acid hydrolysis
Alkaline hydrolysis
Chemical oxidation
Alkaline hydrolysis
Acid hydrolysis
Chemical oxidation
Complete degradation
Complete degradation
Unknown degradation rate
Complete degradation
Slow degradation rate
Slow degradation rate
Complete degradation
Alkaline salts of destaethylfenchlorophos have unknown toxicicies.
Alkaline salts of 0,0-dimethyl phosphorothioate and 2,4,5-
trichlorophenol. The trichlorophenol Is more toxic than rcnnei.
Initial products are alkaline salts of 0,0-dimethylphosphoro-
thloate and N-methyl u-nercaptoacetanide. The amide subsequently
hydrolyzes to a-mercaptoacetic acid and methylamlne. Mercapto-
acetic acid Is about as toxic as dlmethoate.
Essentially the same products as alkaline hydrolysis.
Initial products are alkaline salts of 0-ethyl ethylphosphono-
thloate and phenyl mercaptan. Phenylmercaptan can oxidize to
yield dlphenyl disulfide. Phenyl mercaptan is toxic (oral L£-0
of 46 mg/kg).
The products probably include diphenyl disulfide. Intermediates
include the more toxic oxon and possibly phenyl mercaptan.
Final products phosphoric acid salts and ethyl mercaptan are
non-toxic.
Essentially the same as alkaline hydrolysis.
Unknown products. One product appears to be dlhi'tyl sulfide.
-------
Table 14. Summary of Effects of Chemical Treatment on Pesticides
for which No Chemical Treatment is Recommended (Cont'd).
Pesticide
Chemical Treatment
Degree of Degradation
Identity and Environmental Hazard of
Degradation Products
EPIC
(Eptam)
Molinate
(Ordram)
Alkaline hydrolvsis
Alkaline hydrolysis
Slow reaction
Strong acid hydrolysis Complete degradation
Chemical oxidation Unknown
Slow reaction
Diisopropylamine and ethyl mercaptan are more Loxi: :- ra:s :han
EPTC.
Diisopropylamine and ethyl mercaptan are more toxic " rac= :ha"
EPTC.
Di n_-propylamine is non-toxic. No toxicity inf orma: i o- r^r
ethanesulfonic acid was found.
Hydrolysis product hexamethylenimine is more toxic char, zclir.ate.
Ui
Thiram
Propanil
^ui.oroxuron
Chemical reduction by
necals or sulfide
Chemical reduction with
cyanide ion
Chemical reduction with
acetone or acetate
Complete degradation
Complete degradation
Complete degradation
A.:id or alkaline hydrolysis Complete degradation
: 1~ hydrolysis
Unknown hydrolysis rate
Initial products are dimethyl dithiocarbamic acid salts, soie cf
which are carcinogenic. When acidified, the salts cegrace ^o
diethylamine and carbon disulfide. Carbon disulfide is relatively
non-toxic but is inflammable and has noxious organoiepc1C properties.
Thiocyanate ion and the monosulfide have no evidence ?i carcino-
genic effects.
Products include CS-, COS, dimethylamine, and other products. CS,
and COS are low boiling, inflammable, and have obnoxious organolepic
properties.
Propanoic acid is rioh-toxic; 2,4-dlchloroaniline is slightly less
toxic than propahll, but it is metabolized to persistent azobenzenes
Carbon dioxide is non-toxic; methylamine is slightly "xi:; and
p_(j>-chl6rophenoxyl)aniline toxicity is unknown.
-------
Table 14. Summary of Effects of Chemical Treatment on Pesticides
for which No Chemical Treatment is Recommended (Cont'd).
Pesticide
Chemical Treatment
Degree of Degradation
Identity and Environmental Hazard of
Degradation Products
Diphenamid
Simazine
Cyanazine
(Bladex)
Alkaline hydrolysis
Strong acid or alkaline
hydrolysis
Chemical hydrolysis
Slow reaction
Complete degradation
Unknown rate
Phenylacetic acid and dimethylamine are less phytocoxic.
Hydroxysimazine is not herbicidally active.
Intermediate products include the products from -CS nyirelysi;
to amide and to acid. The chloride is also hydrolyzed :c yieli
the hydroxy-s_-triazene. Toxlcities of these products are net
available.
Aminotriazole
(Amitrole)
PCNB
(Terrachlor)
DNBP
(Dinoseb)
Derivatization with
ketones and aldehydes
Derivatization with aryl
chlorides or anhydrides
Alkaline hydrolysis
Chemical reduction
Chemical oxidation
Chemical reduction
Alkylation
Fast reaction
Fast reaction
Complete degradation
Complete degradation
Unknown reaction rate
Unknown reaction race
Unknown reaction rate
Effect on toxicity is unknown.
Effect on toxicity is unknown.
Pentachlorophenol and nitrate are formed. Pentachlorophe^ol is a
toxic pesticide which should be disposed by ground disposal.
Pentachloroaniline toxicity is unknown.
Toxicity of dinitrobenzoic acid is not known. The use of trie
oxldants require technical skills by the user.
Final products are amines. Intermediate products are unknovr..
Product toxicities are unknown.
Toxicity of the products is unknown.
-------
Table 14. Summary of Effects of Chemical Treatment on Pesticides
for which No Chemical Treatment is Recommended (Cont'd).
Pesticide
Chemical Treatment
Degree of Degradation
Identity and Environmental Hazard of
Degradation Products
Chloroplcrin
UJ
CO
Reaction with alkoxide Complete degradation
Heating with fuming sulfuric Complete degradation
acid
Heating with hydriodic acid Complete degradation
Heating with iodide salts Complete degradation
Heating with ammonia Complete degradation
Heating with sodium peroxide Complete degradation
Reaction with mercaptide ion Complete degradation
Reaction with trialkyl-
phosphine
Heating with zinc plus
acetic acid
Complete degradation
Complete degradation
Alkyl orthocarbonate esters, chloride, and nitrate are non-toxic
Phosgene and nitrosyl chloride are toxic.
Ammonia, carbon dioxide, hydrogen chloride, and iodine are less
toxic than chloropicrln.
Carbon tetraiodide could be carcinogenic.
Cuanldlne is non-toxic.
Carbonate, chloride, and nitrate salts of sodium are non-toxic.
Disulfide and a mixture of carbon dioxide, nitrogen, carbon
monoxide and nitrousoxide are the products. They are less toxic
than chloropicrin.
Trialkylphosphonium dialkylpliosphonium dichloride and a mixture
of carbon dioxide, nitrogen, carbon monoxide, and nitrous oxide
are the products. They are less toxic than chloropicrir..
Methylamine and chloride ion are non-toxic.
Chlorobenzilate
Acid hydrolysis
Alkaline hydrolysis
Complete degradation
Complete degradation
£-£?-dichlorobenzophenone oral toxicity is not known.
The initial product is sodium Chlorobenzilate which hydrolyzes to
£,£'-dichlorobenzophenone when acidified.
-------
Table 14. Summary of Effects of Chemical Treatment on Pesticides
for which No Chemical Treatment is Recommended (Cont'd).
Pesticide
Chemical Treatment
Degree of Degradation
Identity and Environmental Hazard of
Degradation Products
2,4,5-T
Endrin
Dibromochloropropane
(DBCP)
Chlorinolysis at
approximately 85'C
Chlorinolysis above 400"C
Strong acid hydrolysis
Partial degradation
Complete degradation
Complete degradation
Reaction with alkali metals Complete degradation
in liquid ammonia
Photochemical reaction in Complete degradation
hydrocarbon solution
Acid treatment at 100°C or Complete degradation
thermal treatment
Photochemical treatment Complete degradation
Treatment with sodium Complete degradation
mechoxlde in dimethyl aulf-
oxide
Reduction with metals or Slow reaction to complete
metal complexes degradation
Mild alkaline hydrolysis Complete degradation
Strong alkaline hydrolysis Complete degradation
Herbicidally inactive products. Their mammalian toxicity is
unknown.
Carbon tetrachlorlde, phosgene and hydrogen chloride are toxic.
2,4,5-trichlorophenol is pesticidal. Formaldehyde is slightly
toxic, but an irritant. Carbon dioxide is non-toxic.
Unknown products.
Degradation of the tetrachlorodioxin impurity in 2,4,5-T.
Products are rearranged isomers: an alcohol, ketone, and alde-
hyde. They are less toxic than endrin.
Products include those obtained from acid or thermal treatment, .
plus an additional production containing one carbon-chlorine bond
reduced to a carbon-hydrogen bond.
Reduction of one carbon-chlorine bond to a carbon-hydrogen bond.
Product toxicity is not known.
Rearranged and dechlorinated products. Their toxicities are
unknown.
2-bromoallyl alcohol Is a potential carcinogen.-
Propargyl alcohol is more toxic than DBCP.
-------
Table 14. Summary of Effects of Chemical Treatment on Pesticides
for which No Chemical Treatment is Recommended (Cont'd).
Pesticide
Chemical Treatment
Degree of Degradation
Identity and Environmental Hazard of
Degradation Products
Dibromochloropropane (Cont'd.)
Reaction with potassium
ethoxide
Alkali metals in liquid
ammonia
Chemical reduction
Complete degradation
Complete degradation
Complete degradation
Ethyl propargyl alcohol is probably only mildly to:ic.
Products and their toxicities are unknown.
Products depend upon conditions. Final products are non-toxic
hydrocarbons. Intermediates are halogenated propanes.
D-D
Mild alkaline hydrolysis Complete degradation
Strong alkaline hydrolysis Complete degradation
Hydrolysis at 200°C or 150°C Complete degradation
with PbO
Chemical reduction Slow reaction
^-chloroallyl alcohol is a potential carcinogen.
Propargyl alcohol is more toxic than D-D.
Acetone and propionaldehyde are non-toxic.
Products not specified.
Dicamba
Hydrolysis
Chemical oxidation
Alkali metal in ammonia
No reaction
No .reaction
Complete degradation
Products are unknown.
MSMA
Chemical oxidation
Reaction with sulfide
Complete degradation
Complete degradation
Arsenic acid is more toxic.
Methylarsenic dlsulfide is of unknown toxicity.
Arsenic acid
Reaction with sulfide
Complete degradation
Arsenic sulfide is a less hazardous precipitate.
-------
Table 14. Summary of Effects of Chemical Treatment on Pesticides
for which No Chemical Treatment is Recommended (Cont'd).
Pesticide
Chemical Treatment
Degree of Degradation
Identity and Environmental Hazard of
Degradation Products
Sodiumfluoroacetate
(Compound 1080)
Acid or alkaline hydrolysis Very slow reaction
Chemical oxidation No reaction
Fluoride ion Is slightly toxic. No other products identified.
Creosote
Chemical oxidation
Unknown reaction rate
Unknown reaction products.
Warfarin
BHC
(HCH)
(Lindane)
Paraquat
Heating with alkali
Heating with acid in
alcohols
Reaction with amines
Alkaline hydrolysis
Chemical reduction
Alkaline hydrolysis
Oxidation with hydrogen
peroxide
Oxidation with aqueous
permanganate, chlorine, or
chlorine dioxide
Complete degradation
Unknown reaction rate
Complete reaction
Complete degradation
Complete degradation
3-(£-hydroxyphenyl)-5-phenyl-2-cyclohexene-l-one. Toxicity
unknown.
Product ketal has unknown toxiclty.
Schiff base derivatives are produced. Their toxicities are
unknown.
Chloride and a mixture of trichlorobenzenes are formed. Chloride
is non-toxic. Trichlorobenzenes are not acutely toxic and have no
known long-term effects. They are, however, persistent and can
potentially bioaccumulate.
Chloride is non-toxic. Benzene has a low acute toxicity but has
given positive carcinogenic tests.
Unknown extent of degradation An .undefined resinous material of unknown toxicity is formed.
Varies Weak H.O yields the pyridone, dipyridone, 4-carboxyl-l-methyl-
pyridinium ion, and possibly 4-carboxyl-l-methylpyridone; product
toxicities are unknown. Strong oxidizing conditions yeild oxalic
acid which is non-toxic, but reaction rate is unknown.
Fast reaction Products of chlorine dioxide reaction are ammonia and oxalic
acid which are non-toxic. These are also postulated products
from permanganate or chlorine oxidations, but have not been
demonstrated. The chlorine oxidation requires pH greater than 11.
Very high ratios of oxldant:paraquat are required.
-------
The ,-j l.lernat Lves for their disposal, have been discussed in Section 3. In
order of prefercd use t.he recommended disposal is: (1) incineration nt a
siiilahle facility (for all except the arsenicals); (2) disposal Ln a specially
designated landfill; and (3) land burial, sometimes with chemical treatment.
Proper facilities are scarce for the first two alternatives.
Alkaline hydrolysis is the only detoxification procedure recommended; the
pesticides which can be hydrolyzed are members of the phosphorus-containing
pesticides (monocrotophos; phosphamidon; fensulfothion; PennCap-M (micro-
encapsulated methyl parathion); disulfoton; phorate; and methamidophos),
carbamates (carbofuran, aldicarb, and methomyl), and captafol of the nitrogen-
containing pesticides. Some chemical treatments which are potentially useful
to reduce hazard of a few of the pesticides in land burial, should be tested.
These treatments include precipitation of the arsenicals with divalent cations
(e.g., calcium), acidification of dinoseb, dicamba and warfarin sodium to
reduce leaching rate and mixing simazine and cyanazine with lime to assist
degradation.
Recommendations for further study have been based on three problem areas:
n disposal method has been derived from existing data from laboratory studies
but has not been field tested; information suggests that.a method is feasible
but some data is lacking and no practical method can be recommended; and in-
sufficient data is available to devise an approach. The following areas of
research are recommended:
- Field test all recommended procedures in this study and the companion
work (1).
- Examine the use of aqueous and ethanolic iodide containing solutions as
detoxicants for phosphorus-containing pesticides.
-------
- Determine the hydrolysis kinetics for fensulfothion.
- Determine the hydrolysis products from dimethoate with strong caustic
(1-2N NaOH).
- Determine the hydrolysis kinetics for methamidophos (Monitor) in aqueous
acid.
- Evaluate a two step detoxification for Dyfonate consisting of alkaline
hydrolysis followed by oxidation with household chlorine bleach.
- Determine toxicity and environmental fate of 2,2-dimethyl 2,3-dihydro-
fensofuran-7-ol which is produced by alkaline hydrolysis of carbofuran.
- Determine the toxicity of methyl N-hydroxyacetimidate which is produced
by alkaline hydrolysis of methomyl.
- Evaluate zinc-acetic acid (or hydrochloric acid) as a detoxicant for
chloropicrin, endrin, D-D, BHC, and DBCP.
- Evaluate iron salts as a detoxicant for endrin.
- Determine environmental fate and toxicity of the trichlorobenzenes
produced from BHC (and lindane) hydrolysis in caustic.
- Evaluate alkanolamines as a detoxicant for DBCP.
- Evaluate if precipitation of MSMA or arsenic acid with sulfide or a
suitable cation (Ca^"1", Mg^+j Or Fe^+) yields a product acceptable
for land disposal.
- Evaluate if the triazenes simazine and cyanazine can be adequately
disposed by mixing with lime and land burial.
- Further evaluate alkaline hydrolysis and chemical oxidation for
paraquat detoxification.
-------
APPENDIX A
CIIKMICAI. MKTIIODS KOK TIIK DKCKADATI ON/DKTOX I !•'I CAT I ON
OK I'HOSPIIORUS-CONTAI.NING PKSTJCIDKS
A.I GENERAL REVIEW OF APPLICABLE DISPOSAL METHODS
All the phosphorus-containing pesticides selected for this study are ester
or amide derivatives of ortho-phosphoric acid or thiophosphoric acids (H PO. S
j 4—n n
where n = 0 to 3). The general structure of the selected pesticides is:
Rrf-R3
R2
where X is either 0 or S, R = R are usually either methoxide (CH 0-) or
-L Z J
ethox.ide (C^O-) radical, and R3 is an alcohol, phenol, mercaptan or amine
group (8-10). Table 15 summarizes the selected organo-phosphorus pesticides
and their chemical structures. The pesticides methamidophos (Monitor), Dyfonate,
and Del differ slightly from the generalized structure, but their chemical
reactivity remains fundamentally the same. Def is a phosphorotrithioate
derivative (R^ = R^ = R = n-butylmercaptide). Methamidophos is an amide
containing mixed ester groups (methoxide and methyl mercaptide). Dyfonale is
a phosphonodithioate (R = ethyl).
The most important chemical detoxification method for the selected organo-
phosphates is hydrolysis, which removes one of the ester groups to yield a
phosphate diester. Shih and Dal Porto have discussed some characteristics of
the phosphate hydrolysis (1). Their general discussion did not provide a suit-
able description of the kinetic and mechanistic problems. A complete description
-------
Table 15. Chemical Structure of Selected Phosphorus-Containing Pesticides.
Ul
Pesticide Name
Common
Ronnel
Trade
Monocretophos Azodrin
Phosphamidon Dimecron
Fensulfothion Dasanit
Korlan
Structure
R2
0 CH 0 CH 0
J
0
S C2H 0
CNHCH3
Molecular Weight (g)
223.2
299.7
308.3
321.6
Dimethoate
Disulfoton
Phorate
Cygon
Di-Syston
Thimet
Methamidophos Monitor
Def
DEF
S
S
0
0
-S-CH2C
8
229.2
274.4
260.4
141.1
333.6
-------
Table 15. Chemical Structure of Selected Phosphorus-Containing Pesticides (Cont'd).
Pesticide Name Structure3
Common Trade X R R R Molecular Weight (g)
1 f- j
(Microencapsulated)
Methylparathion PennCap M S CH 0 CH-0 ~°~~4 /)—N02 291.3
Dyfonate Dyfonate S C2H5° C?H5 ~S-/ J 246.3
R2
-------
99.9% degradation from the kinetic expression:
|| o k(a-x)(b-x) A-l
where a and b are the initial concentrations of organophosphorus pesticide and
of hydroxide (or protlum), respectively; x is the decrease in organophosphate
pesticide concentration after time t; and k is the reaction rate constant.
This rate equation errs in the stoichiometry of the hydrolysis (13, 14).
Alkaline hydrolysis could utilize two or more moles of hydroxyl ion per mole of
insecticide hydrolyzed. Also, the hydrolysis in acid media does not consume
hydrogen ions. The rate expression will differ for the acid and alkaline
hydrolyses. Equation A-l implies that rate constant, k, is completely pH
independent, which is not true (see the Shih and Dal Porto discussion on
Chemical Methods for the Degradation/Detoxification of Diazinon) (1). A bell-
shaped relationship between hydrolysis rate constants and pH for a series
of organophosphorus Insecticides has been demonstrated (13). This pH profile
implies that several hydrolysis mechanisms operate and each has an unique rate
constant. The scheme below can account for hydrolysis kinetics and mechanism:
- kl
A + OH =—> Products
k2
A + H20 >• Products
+ K + k3
A + H •*- HA + H-0 »• Products
where A is the organophosphorus pesticide; K is the equilibrium constant for
pesticide protonation; and k_, k., and k_ are the observed hydrolysis rate
constants for reactions of pesticide with hydroxyl ion, of pesticide with
water, and protonated pesticide with water, respectively. Since multiple
-------
mechanisms could operate at any of these three reactions, the observed rate
constants k , k..., and k. could be composites of several rate constants.
K(|unL:ion (y\-2) describes kinetics for organophosphorus pesticide hydrolysis at
any pH:
dx
A-2
where C , C -, C +, and C are concentrations of the pesticide, hydroxyl
A Un n H_U
ion, hydrogen ion and water, respectively (9). This equation reduces to the
expression:
dx
dt
k,K
1 W
-1- lr -*- Ir VC -4-
V +> + "3KCH+
A-3
where K is the dissociation constant for water. Observed kinetic data (9, 13)
w
—8
suggest that at pH greater than 8 (Cu+ <10 molar), the term k, K /C +
H JL W H
dominates and the term reduces to:
This can be expressed as Equation (A-5):
A-4
(a-x) (b-nx)
A-5
where n is the number of equivalents of hydroxide consumed per mole of organo-
phosphate degraded. Integration yields:
50
-------
kt
b-na
In
(t)
A-6
Equation (A-6) was used to calculate hydrolysis times. Equation (A-7) which
was used to calculate the time for 99.9% (t Q ggg) pesticide degradation is
derived from Equation (A-7):
0.999
(b^I)kln (
IQQOb - 999na
b >
A-7
51
-------
A. 2 (JHKMICAI, METHODS FOR DETOX I b" [.CATION OF MONOCROTOPHOS
Moiiocrotoplios (A/.odrin) is a systemic i nstr.t J.cide-acarac j dc which is used
chiefly against cotl.iin pests. IL Ls nriscib.Le with water, soluble in acetone-.
and alcohol, and very slightly soluble in kerosene and diesel fuel (14, 15).
Azodrin is mostly marketed as a water miscible formulation containing 3.2 Ib/gal
but is also available as 5 Ib/gal and as 80% wettable powder (15, 16).
Azodrin is relatively stable to heat; decomposition rate is 0.005, 0.02,
and 0.085% per day at 20°, 30° and 40°C, respectively (17). It reacts with
bromine to yield the dibromide and a bromovinyl analogue (18) :
0 0 0 0
ii n Br n n
(CH30)2POC(CH3)=CHCNHCH3 - ^ (CH 0)2POC(CH )BrCHBrCNHCH +
0 0
ii n
(CH^O) nPOC (CH_ )=CBrCNHCH^
j 2. 3 3
Sodium iodide in acetone removes a methyl ester group and yields the desmethyl
derivative (18). Methyl iodide is slightly toxic (oral LD = 220 mg/kg for
rats) (4). Desmethyl monocrotophos is not an acetylcholinesterase inhibitor
Kinetic and product data suggest that alkaline hydrolysis will yield non-
toxic products in a reasonable time period; Table 16 summarizes salient kinetic
data. Brown trt _al. describes products and kinetics (19); alkaline hydrolysis
yields dimethyl phosphate, acetone, methylamine and carbon dioxide.
00 CH H
ii " _ 9 _ 3N /
(CH 0)2POC(CH3)=CHCNHCH + OH ^ (CH^O^PO + ^>C,
HO riJII'.'ll
3 H <>
V-r' - "
/^ \ + OH > CH CCH1
HO CNHCH
n 3
0
-------
Table 16. Effect of pH and Temperature on the
Hydrolysis of Monocrotophos.
Temperature
100
50
100
100
50
38
50
26
_ £S_
3
3
A. 6
7
7
7
12
6.2
Rate
First order Second order
sec'1 11 (mole-sec) Half life
-4
1.3x10 — 1.5 hr
l.lxlO~6 — 180 hr
80 min.
5.2xlO~4 — 0.37 hr
3.4xlO~6 — 57 hr
23 days
0.75xlO~2
9% degrada-
tion in 1 wk
Reference
Brown (19)
Brown (19)
Zweig (18)
Brown (19)
Brown (19)
Zweig (18)
Brown (19)
Seiber and
Markel (20)
53
-------
Since kinetic data was not found for monocrotophos hydrolysis at ambient
temperature, the required time had to be estimated from the available data,
T.-ifole 16. Several assumptions were necessary. It is assumed that the rate
constants follow the Arrenhius Equation (21):
k = Aexp(-E /RT) A-8
where E is the activation energy, R is the gas constant, T is the absolute
A
temperature and A is a constant. If E is known, the hydrolysis rate can be
calculated at any temperature by Equation (A-9):
Iog(k1/k2) = (0.219EA) (1/1 2 - 1/T^ A-9
Although Table 16 does not contain sufficient information to calculate
an activation energy for the alkaline hydrolysis, a reasonable estimate can be
derived. Gomaa et al. have demonstrated that activation energies are similar
for the acidic and basic hydrolyses of diazinon (21). It is assumed by reason
of analogy that the acidic and basic hydrolyses of monocrotophos also have
similar activation energies. Table 16 yielded activation energies of 22.8 and
24.1 kcal/mole for the pH 3 and pH 7 hydrolyses, respectively. With a 24 kcal/-
mole activation energy assumed for the alkaline hydrolysis, the bimolecular
_3
rate constant at pH 12 was 0.32 x 10 I/mole-second. The time for 99.9% degra-
dation (t ) for its hydrolysis in strong base was calculated from Equation
(A- 7) with n = 1, since stoichiometry requires a minimum of 1:1 hydroxide to
monocrotophos ratio. Table 17 presents calculated t for monocrotophos
using approximately four to five mole ratio of base to pesticide.
54
-------
Table 17. Estimated Time for 99.9% Hydrolysis of Monocrotophos
by IN Sodium Hydroxide.
Formulation
Azodrin
Content
3.2 Ib/gal
(watermiscible)
4.0 Ib/gal
(watermiscible)
80% wettable
powder
1.72
2.18
1.63
mole /liter
mole/liter
mole/pound
With IN
Pesticide-
Base Ratio
1:7
1:10
1 Ib
(vol/vol)
(vol/vol)
:7£
NaOH
0.999
8.
8.
7.
(Hours)
7
0
5
With 2N
Pesticide-
Base Ratio
1:4
1:5
1 Ib
(vol/vol)
(vol/vol)
:3.5H
NaOH
'0.999
4.5
3.5
3.2
(Hours)
-------
Kmpty containers (bottles and drums) should be thorough l.y drained then
irip.le rinsed witli a caustic rinse. Kmpty bags should be disposed by the KPA
recommended procedures (Section 3) (7a).
56
-------
A.3 CHEMICAL METHODS FOR DETOXIFICATION OF PHOSPHAMIDON
Phosphamidon (Dimecron) is a systemic insecticide-acaricide, which is
applied to a wide variety of perennial and annual crops. It is marketed as a
liquid (8 Ibs/gal) and soluble concentrates (20, 50, and 100% weight volume).
Phosphamidon is water tnlscible and soluble in most organic solvents except
saturated hydrocarbons (14, 15, 22).
Phosphamidon is stable at room temperature and decomposes above 160?C.
Nucleophiles such as iodide and mercaptide ion react at the methyl ester'and
yield desmethylphosphamidon (8, 17, 23). The product toxicities are expected
to be similar to but less toxic than phosphamidon (Section A.2).
Aqueous hydrolysis appears to be a suitable detoxification procedure.
Table 18 summarizes the published phosphamidon hydrolysis data. It is rela-
tively stable in the pH range 2 to 8 but will hydrolyze fairly rapidly above
pH 10. Phosphamidon actual consists of two geometrical isomers which hydrol-
yze at slightly different rates. The isomers differ by the geometry of the
double bond; the methyl group and chloride can be cis or trans. The insecti-
cide contains a cis- to trans- isomer ratio of approximately 70:30. The cis-
isomer is the more reactive (23).
Hydrolysis products are pH dependent. Acidic hydrolysis yields a-
chloroacetoacetic acid diethylamide (17). The amide can subsequently degrade
to diethyl amine, carbon dioxide and chloroacetone in strong acid or with
heating. A different series of products have been identified for the alkaline
hydrolysis. Although the diethyl amide of a-chloroacetoacetic acid appears to
initially form, it very rapidly hydrolyzes, even in weak alkaline solution,
and yields chloride and the diethylamide of a-hydroxyacetoacetic acid (8, 24).
57
-------
Table 18. Kinetic Data for Hydrolysis of Phosphamidon
pH Temperature, °C Initial half-life
4
4
7
7
10
10
10
12
Ethanol-pH 6
buffer (20:80)
23
45
23
45
23
45
27
27
70
70
74 days
6.6 days
13.8 days
2.1 days
2.2 days
3.3 hours
cis=300 hours
trans=100 hours
cis=2 hour
trans =1 hour
Isomer I = 10.5 hr
o
Isomer II = 14 hr
Reference
Anliker & Beriger
Anliker & Beriger
Anliker & Beriger
Anliker & Beriger
Anliker & Beriger
Anliker & Beriger
Bull £t al. (25)
Bull £t aJL (25)
(24)
(24)
(24)
(24)
(24)
(24)
Ruzicka e_£ al. (26)
Ruzicka et al. (26)
Ruzicka et al. (26) report that Isomer II is apparently the major isomer.
58
-------
0 0
II II
K )2 + 20H > (CH 0) PO + Cl"
0
n
In strong alkali this amide can slowly hydrolyze to yield acetic acid and gly-
colic acid diethylamide. The product, glycolic acid, diethylamide is stable in
base (26). The hydrolysis products are non-toxic and rapidly assimilated into
natural constituents (25).
28 2 '',?.'
CH3CCH(OH)CN(C2H5)2 + OH
The hydroxide-phosphamidon stoichiometry for a complete hydrolysis requires
some speculation. A 2:1 stoichiometry, the minimum required, yields the amide
of a-hydroxyacetoacetic acid. Although the hydrolysis of this amide would
increase the stoichiometry to a 3:1 ratio, data of Anlinker and coworkers
suggest that its rate does not compete with phosphamidon hydrolysis (27). So,
a 2:1 stoichiometry is considered the best estimate and t _ Qqq is calculated
from Equation (A-7) with n = 2. The bimolecular rate constant, k, can be
estimated from the data of Bull et^ al. (25). Since their hydrolysis used low
phosphamidon concentration (b»a), Equation (A-10) can be derived for half-life
from the general expression in Equation (A-6):
, In 2 . in
k = A-10
SH"^
k equal to 36 ^/mole-hour was calculated from the 2 hour half-life at pH 12 for
cis-phosphamidon.
59
-------
Table 19 summarizes approximate times for phosphamidon hydrolysis at
ambient temperature using about 5-6 to 1 ratio of base to phosphamidon. Total
degradation is achieved within 10 minutes using 2N aqueous sodium hydroxide.
Empty containers should be decontaminated by the triple rinse using an alkaline
rinse solution (Section 3).
60
-------
Table 19. Time Required for 99.9 Percent Phosphamidon Degradation
with Aqueous Sodium Hydroxide at 27°C.
Phosphamidon
Content
Formulation Ib/gal moles/liter
With IN NaOH
Pesticide- t,
With 2N NaOH
Pesticide- t.
0.999 *«-«•—- "0.999
Base Ratio (min.) Base Ratio (min.)
(vol/vol) (vol/vol) '_
Liquid
8
Soluble
concentrate 10
3.2
4.0
10:1
15:1
30.6
24
8:1
10:1
7.8
7.8
61
-------
A.4 CHEMICAL METHODS FOR DETOXIFICATION OF FENSULFOTHION
Fensulfothion (Dasanit) is a nematocide-insecticide which is mainly employed
in soil treatment. It is formulated as a spray concentrate (6 Ibs/gal), 5%,
10%, and 15% granular, and 10% dust. Fensulfothion is slightly water soluble
(1.6 g/&) and soluble in most organic solvents with exception of saturated
hydrocarbons (14, 15).
Chemical oxidants such as peroxides oxidize the sulfoxide group to sulfone
(8)
S
n
It also reacts by the thiono-thiolo rearrangement
Both these reactions yield toxic products.
Although no direct information was found to describe hydrolysis rates or
product toxicities, excellent data which exists for analogs was used as estima-
tions for hydrolysis rates of fensulfothion. Its hydrolysis products are j>-
methylsulfinylphenol and 0,0-diethyl phosphorothioic acid (8). The diester of
phosphoirothioic acid is non-toxic. Although no toxicological data was found
for j>-methylsulfinylphenol, oral toxicity (rats) for the analogous £-(N-methyl-
sulfamoyl) phenol is low, LD = 2500 mg/kg (4). If it is safe to assume that
62
-------
HO-// \S-SNHCH,, HO-
£-(N-methylsulfamoyl)phenol £-raethylsulfinyl phenol
£-methylsulfinylphenol has an oral toxicity of the same magnitude, then fen-
sulfothion hydrolysis products are non-toxic. Muhlman and Schrader described
kinetics for an oxon analog, Preparation S-776, (13).
Oxons have a greater susceptibility to hydrolysis than corresponding thions.
Hydrolysis rate constants for the thions are within a factor of ten of the
oxons (10, 13). Table 20 summarizes kinetic data for Preparation S-776; the pH
dependence of hydrolysis rate is typical of organophosphate pesticides.
Alkaline hydrolysis at room temperature appears a feasible approach.
Time for 99.9% degradation, t „ ___, was calculated from Equation (A-7).
Overall stoichiometry of 2:1 hydroxide-fensulfothion will account for hydrol-
ysis and neutralization of acidic products:
20H
The rate constant, k, for ambient temperature, ca. 25°C, was estimated from the
data in Table 20. Activation energy was calculated as 22.4 kcal/mole from the
Arrhenius relationship, Equation (A-9). Applied to kinetic data for pH 9,
63
-------
Table 20. Kinetic Data for the Hydrolysis of S-776
(Analog of Fensulfothion). From Muhlman
and Schrader (13).
Temperature, °C pH
0 1-5
10 1-5
20 1-5
30 1-5
40 1-5
50 1-5
60 1-5
70 1-5
70 nHCl
70 1
70 2
70 3
70 4
70 5
70 6
70 7
70 8
70 9
k (hours 1)xl02
5.4xlO~4
2.4xlO~3
9xlO~3
3.1xlO~2
l.OxlO"1
3.0X10"1
g.Oxio"1
2.40
8.38
3.56
3.11
3.06
3.36
3.56
4.48
8.0
8.17
25.6
Half-life
5350 days
1200 days
320 days
93 days
29 days
9.6 days
3.2 days
1.2 days
8.3 hours
19.5 hours
22.3 hours
22.6 hours
20.6 hours
19.5 hours
15.5 hours
8.7 hours
8.5 hours
2.7 hours
64
-------
— 3 —1
values of 1.84 x 10 hour and 3.07 1/mole-min. were obtained for the
pseudo-first order (k ) and second order rate constants (k_), respectively,
for Preparation S-5776 (Equation A-ll). The approximate t of fenBulfo-
U • y 7-/
thion was calculated with an estimated second order rate of 0.31 5,/mole-min.,
which is an order of magnitude less than for Preparation S-776.
k2
The estimated t _ qqq values are summarized in Table 21. Sodium hydroxide
in 50% aqueous ethanol should be used for the hydrolysis, since the fensulfo-
thion is only slightly soluble in water. The minimum degradation time for the
spray concentrate is about 20 minutes with 2N base. The minimum time for
granular and dust formulations which was estimated at approximately one-half
hour requires additional time for the active ingredient to desorb into solu-
tion.
Empty containers should be thoroughly drained and then treated with a
caustic rinse. Since aqueous solubility for fensulfothion is low, caustic in
50% aqueous ethanol is suggested. Empty bags should be disposed by the EPA
recommended procedures (Section 3) (7a).
65
-------
Table 21. Estimated Time Required for 99.9 Percent Fensulfothion
I)t'j>,r;id;i t i on with Sodium Hydroxide in 50% Aqueous Ivtlinnol.
FcnsulIothion
Formulation Content
_w'' J' J N_
Pesticide- t().999
Base Ratio (min.)
Wi Ui__2N N^
Pesticide- . t
Base Ratio (min.)
Spray
concentrate 6 Ib/gal 2.32 mole/2, 12:1 (v/v) 37.1
6:1 (v/v) 19.8
Granular
Granular
Dust
15%
10%
10%
0.22 mole/ 1.2 £/lb 28.1
Ib
0.15 mole/ 0.6 fc/lb 28.1
Ib
0.15 mole/ 0.6 £/lb 28.1
Ib
66
-------
A.5 CHEMICAL METHODS FOR DETOXIFICATION OF RONNEL
Ronnel (fenchlorophos, Korlan) is used as an animal systemic and a struc-
tural, residual spray insecticide. It's formulations include emulsifiable
concentrate (2 and 4 Ib/gal) and 50% granular. Ronnel is stable at ambient
temperature, but decomposes above 80°C. Solubility is 44 ppm (14, 15).
Although ronnel hydrolyzes relatively rapidly, the products hydrolysis
remain relatively toxic. Cowart ^£ jil- determined ronnel loss in distilled
water (pH approximately 6) (29). At ambient temperature apparent degradation
was 40% at 2 days and 95% at one week. Ruzicka et al. reported half-life of
10.4 hours for ronnel hydrolysis at 70° in 80% pH 6 buffer - 20% ethanol (26).
Hydrolysis products vary with alkaline content, while weak caustic hydrolyzes
ronnel at the methyl ester, strong alkali cleaves the phenolic ester group
(30).
0
weak alkali CH.OPOC,H C1 -I- CH.OH
1 >• J . D 2 J J
strong alkali (CH30)2P-0 + Cl ^^ Cl
The strong alkali hydrolysis product, 2,4,5-trichlorophenol is more toxic than
ronnel, oral LD,. of 802 mg/kg and 906 mg/kg, respectively for rats (4).
Ronnel should be disposed by a non-chemical method. The EPA recommended
procedures should be followed (7a). Containers emptied of ronnel should be
cleaned by the NACA recommended triple rinse method with water. Aqueous
caustic which is generally recommended for the organophosphorus pesticides
should not be used, because of the higher toxicity of 2,4,5-trichlorophenol.
67
-------
A. 6 CHEMICAL METHODS FOR DETOXIFICATION OF DIMETHOATE
Dimethoate (Cygon) is a systemic insecticide-acaricide with a wide range
of applications, including agricultural crops, ornamental plants, and house
fly control (14, 15). It is soluble in alcohols and ketones, less soluble in
aliphatic and aromatic hydrocarbons. Aqueous solubility is listed as 25 g/&
by Martin and Worthing (15) and 39 g/& by Melnikov (28). Most dimethoate is
formulated as 23.4% (2 Ibs/gal) and 43.5% (9 Ibs/gal) emulsifiable concentrate
and 25% wettable powder. It is also formulated as an ULV concentrate (31).
Dimethoate toxicity is potentiated by reactions during its storage
(28, 31). It reacts with 0,0-dimethyl phosphorodithioate to yield desmethyl-
dimethoate and the methylmercaptide ester:
SO S 0 0
ii ii _ - ii _ ii ii
(CH 0) PSCH CNHCH + (CH 0) PS -> (CH 0) PSCH + 0(CHO)PCH CNHCH
When it is heated, dimethoate yields a more toxic isomer by the thiono-thiolo
rearrangement:
S 0
ii . ii
(CH_0).PSR ^—»- CH.OPSR
J / 3 i
CH S
Oral LD values for rats have varied in the literature over the range 147 to
600 mg/kg. This wide range has been attributed to these reactions and possibly
other similar reactions (8, 28, 31, 32).
68
-------
Dimethoate can potentially hydrolyze with bond breakage at the dithio-
phosphate or carbamate portions of its structure. Dimethoate hydrolyzes in
two steps to ultimately yield methylamine, mercaptoacetic acid and phosphoro-
thioate derivatives (8, 23, 31). The kinetics follow the expected pH depen-
dence for organophosphate hydrolysis: at 70°C half-lives were 0.8, 12, and 21
hours for pH 9, 6, and 2, respectively (10). Hydrolysis initiates by P-S bond
clevage to yield N-methyl mercaptoacetamide (33, 34). The amide subsequently
hydrolyzes and yields mercaptoacetic acid and methylamine. The half-lives
reported for the hydrolysis account only for actual dimethoate degradation.
so s o
II II M0U II _ II
(CH OVPSCH-CNHCH. —7-5—^ (CH.O).PSO + HSCH-CNCH,,
J 2. 2. 3 acid or 3 2 23
base
2 HO
HSCH CNHCH- 7-: > HSCH_CO.H + CH0NH_
2. J acid or 22 32
base
Incomplete and conflicting information complicates assessment of hydrol-
ysis as a detoxification method. The broad oral LD range reported for
dimethoate contributes to the evaluation problems. An oral LDrn range of 150
to 250 mg/kg is assumed to best represent the toxicity of technical dimethoate.
The products 0,0-dimethyl phosphorothioate and methylamine are less toxic and
not a problem. The initial hydrolysis product N-methyl mercaptoacetamide
appears to be less toxic than dimethoate. Although an oral LD - was not found
for this product, the parent compound, mercaptoacetamide, has an intraperi-
toneal LD of 300 mg/kg for rats. If toxicity of the N-methyl amide can
LiO
safely be estimated from this value, it is less toxic than technical dimethoate.
69
-------
When the mercaptoacet i.c acid amide further hydrolyzes, it forms mercaptoac.cL i r
arid and nietliyiamine as the terminal products. The oral '-l^t:/-. °': L'l(-' me reap I o-
aceti.c: acid is 250 mg/kg for rats, which is about as toxic as dimethoate. In
conclusion, alkaline hydrolysis is not clearly delineated. Since one of the
hydrolysis products is about as toxic as dimethoate, hydrolysis is judged not
suitable for detoxification.
Dimethoate was oxidized with reagents such as bromine, iodine, and eerie
ion to produce orthophosphate in an analytical scheme (25). Organic products
were not identified.
Waste dimethoate should be disposed in an appropriate, non-chemical
procedure; the EPA recommended procedures should be followed. Empty glass and
metal containers should be triple-rinsed by the NACA recommended method
(Section 3) (7a).
70
-------
A.7 CHEMICAL METHODS FOR CHEMICAL DETOXIFICATION OF DISULFOTON
Disulfoton (Dl-syston) is an insecticide applied at seeding and used as a
folllar spray. It Is formulated mainly as granules (2, 5, and 10%), and also
available as liquid concentrate, seed treatment powder, and is combined in
fertilizer. Disulfoton is soluble in most organic solvents and has a water
solubility of 25 mg/£ (14, 15).
The mercaptide sulfur in disulfoton reacts with alkylatlng agents (such as
methyl halides and methyl sulfate) and oxidants, but products are about as
toxic as disulfoton. The reaction with alkylating agents yields S-alkyl sul-
fonium salts (8, 28):
S
SCH + RX
Disulfoton is oxidized to the corresponding sulfoxide and sulfone, and the
phosphorothioate (8).
Although disulfoton is structurally similar to phorate, its hydrolysis
products differ (Appendix A.8). Its hydrolysis product, ethylthioethyl mer
captan, is not further degraded under normal hydrolysis conditions (18, 35):
S °H
ii or HO
(C0H,.0)0PSC0H/SC0HC s
No toxicity information was found for ethylthioethyl mercaptan. Its toxicity
was estimated from available information on the parent compound, ethanedithiol
71
-------
(IISC II Sll); 1,1) is 100 nig/kg for subcutanaeeous toxic ity for mice (4).
I'll li:incil i I li i o I Loxicil.y is .subslant i a 1 I y li'.ss than disulloLon and it is assumed
I I i;i L elliylthioetliy I rnerc.aptan is also Jess toxic. Dietliy.l phosphorothioic
acid is relatively non-toxic (4).
Disulfoton is more susceptable to alkaline than to acid hydrolysis.
Ruzicka et^ a_l. report a half-life of 32 hours in 1:4 ethanol-pH 6 buffer (26).
Muhlman and Schrader have evaluated pseudo-first order kinetics in water from
pH 1 to 9 at 70°C and at pH 1-5 in temperature range from 0° to 90°C, Table 22
(13). The second order rate constant for ambient temperature hydrolysis was
calculated by use of the Arrhenius relationship as discussed in Appendix A.2
(Equation A-9). Table 22 yielded an activation energy, E , of 24.2 kcal/mole
£\
and a second order rate constant of 4.5x10 £/mole-hour (or 75 £/mole-minute)
at 25°C.
The complete hydrolysis of disulfoton requires an equimolar ratio of
pesticide and hydroxide. Thiols are very weak acids and should not appreciably
consume base. At least 4 mole excess of hydroxide is suggested to insure
complete hydrolysis. A decontaminant of IN sodium hydroxide in 50% aqueous
ethanol is recommended, since disulfoton is only slightly soluble. The time
for 99.9% hydrolysis, t n qqq> was calculated at less than 1 minute by Equation
A-7. Since the disulfoton is formulated as granules, the hydrolysis first
requires desorption and dissolution of the disulfoton; at least a 2 hour
contact period is suggested with frequent stirring. The residue should be
land buried in an area which.will not affect water supplies. Empty containers
should, be thoroughly emptied and disposed in a safe manner (Section 3) (7a).
72
-------
Table 22 . Kinetic Data for the Hydrolysis of Disulfoton
in Water. From Muhlman and Schrader (13).
Temperature, °L j>H
i
70 nHCl
1
2
3
4
5
6
7
8
9
0 1-5
10 1-5
20 1-5
30 1-5
40 1-5
50 1-5
60 1-5
70 1-5
? -i
k(10~ hour *)
2.88
1.11
1.11
1.10
1.11
1.16
1.56
2.50
3.22
9.61
-4
1.2x10
6xlO~4
2.6xlO~3
0.001
0.037
0.12
0.37
1.06
Half-life
24 hours
62 hours
62 hours
62 hours
62 hours
60 hours
44 hours
27.6 hours
21.5 hours
7.2 hours
232000 days
4830 days
1100 days
290 days
78 days
24 days
7.8 days
2.7 days
73
-------
A. 8 CHEMICAL METHODS FOR DETOXIFICATION OF PHORATE
I'liora t.i: (Tliinif.L) (s applied as ;i soil, and systemic Insecticide. 1 1 is
;i v;i i .1 ah l.t- as a Ji(|uid concentrate (6 Ibs/gal) and granular formulation (1UZ and
15%). Its solubility in water is relatively low (50 ppm) . It is miscible with
xylene, carbon tetrachloride, alcohols, ethers, and esters (14, 15, 36).
Phorate is susceptable to hydrolysis. Its hydrolysis apparently initiates
with C-S cleavage to yield ethylthiomethanol and in a second step this product
hydrolyzes to yield formaldehyde and ethyl mercaptan (37).
S H o S
n H2° "
(C2H50)2PSCH2SC2H5 — - " (C2H5°)2PSH + HOCH2SC2H5
acid
These hydrolysis products are all significantly less toxic than phorate : oral
LD (for rats) are 4510, 682, and 800 mg/kg for the diethyl ester of phosphoro-
dithioic acid, ethyl mercaptan, and formaldehyde, respectively (4). Organo-
leptic properties of ethyl mercaptan might be a nuisance; it has an obnoxious
odor (38).
Hydrolysis half-lives at 70°C are 2 hours at pH 8 and 1.75 hours in (1:4)
ethanol-pH 6 buffer solution, respectively (26, 28). Muhlman and Schrader
described effect of temperature on acid catalyzed hydrolysis, Table 23 (13).
Bowman and Casida report a pseudo-first order rate constant of 1.1x10 min.
for hydrolysis at 28°C in 95% ethanol-O.lM aqueous bicarbonate (1:9) containing
500 mg/£ Triton X (32) . Oxidized analogues are hydrolyzed more rapidly than
phorate, but they are more toxic, Table 24.
74
-------
Table 23. Effect of Temperature on Hydrolysis Rate of
Phorate-a From Muh.lmann and Schrader (13).
Temperature, °C
0
10
20
30
40
k (hour 1)xl02
0.014
0.08
0.4
1.83
7.14
Half-life (hours)
200
36
72
1.6
0.4
a
pH 1-5 in water.
75
-------
Table ?./i. Hydro I ysi.s Kales and Toxic Lty ol
I'horati' .'iiid .O-ana.l o^s . a
(C2H50)2PSCH2SC2H5
y
s
s
s
0
0
0
yi Y2 LDb
— — 50 (mg/kg)
8-10
0 - 2-4
0 0 1.8-2.0
0.6-0.8
0 - 1.4-1.6
0 0 0.6-0.8
k[min. )
0.11xlO~3
13xlO~3
15xlO~3
6.6xlO~3
0.28
0.35
Bowman and Casida (37)
Oral LD5Q for rats
Rate for 25 mg pesticide, 25 mg Triton X in 5 ml 95% ethanol plus 45 ml of
aqueous 0.1M sodium carbonate at 28°C.
76
-------
Alkaline hydrolysis is considered the best available detoxification
procedure. The pH of the ethanolic buffer used by Bowman and Casida is
estimated between 8.0 and 8.5 (39). Using the estimate of pH 8.5, the bimo-
iecuiar rate constant of 80 £/mole-sec. was calculated using Equation (A-ll).
Since phorate is relatively water insoluble, 50% aqueous ethanol is recommended
as solvent. Stoichiometry is about 1:1 phorate to hydroxide:
S S
H ii
(C2H50)2PSCH2SC2H5 + °H~ " (C2H50)2PS + CH2° + C2H5SH
A four to five mole excess of hydroxide is suggested as a margin of safety.
The time for 99.9% degradation, t Q ggg, was calculated by Equation (A-7) with
n = 1 at less than 1 minute. Additional time is suggested to allow for disso-
lution and mixing.
Container decontamination with an alkaline rinse is suggested. American
Cyanamid recommends using an aqueous detergent rinse similar to the procedure
described in Table 12 (36). Although phorate has a relatively low water solu-
bility, it hydrolyzes so rapidly that aqueous caustic should be sufficient for
detoxification. This contrasts with recommendations for other hydrolyzable
pesticides of low solubility (Section 3). Empty bags should be disposed as
recommended by the EPA (la).
77
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A.9 CHEMICAL METHODS FOR DETOXIFICATION OF MONITOR
Monitor (methamidophos) is a systemic broad-spectrum insecticide which is
used mainly for vegetable crops. It is marketed as a 4 Ib/gal liquid concen-
t r.-itA-. Monitor is .soluble in water (9 g/100 ml at 20°C), alcohols, and chlor-
inated aliphatic hydrocarbons (14, 15).
Hydrolysis products of Monitor are expected to be pH dependent. Although
no specific information was found for i.ts acid hydrolysis, phosphoramidic acid
derivatives as a class will hydrolyze by P-N bond cleavage (9, 41). Monitor
would yield 0,S-dimethyl phosphorothioate and ammonia. Quistad and coworkers
have examined the alkaline hydrolysis and found that Monitor produced methyl
phosphoramidoate and methyl mercaptan (42):
0
ii
CH.S-P-NH,, + OH > CH_0-PO + CH SH
j I 2. _5 I 2. j
CH30 H2N
-2 -1
The reaction proceeds with a pseudo-first order rate constant of 3.2x10 min
at 30°C in a pH 11.5 buffer, which corresponds to a second order rate constant
of 10.16 £/mole-min (from Equation A-ll). The hydrolysis products are expected
to have significantly less hazards. Methyl mercaptan is a gas at ambient
temperature, boiling point 7.6°C with an aqueous solubility of 23.3 g/£. Its
acute oral and inhalation toxicities are rated moderate (38). The hazard of 0-
methylphosphoramidate is expected to be significantly less than Monitor.
Although its toxicity is not known, phosphoramidic salts are no longer acetyl-
cholinesterase inhibitors (8, 41).
Acid hydrolysis is expected to cleave the P-N bond (9, 41). The expected
hydrolysis products are 0,S-dimethylphosphorathioate and ammonia. Both products
are non-toxic (4). However, no hydrolysis rate information was found.
78
-------
Monitor is oxidized by m-chloroperbenzoic acid in dichloromethane. The
only product identified was CH3SS(02)CH3 (43).
Alkaline hydrolysis is recommended as a method of reducing Monitor's
hazard. Since the hydrolysis stoichiometry requires 1:1 hydroxide to Monitor
ratio, the 99.9% degradation time, t QQQ» *s calculated from Equation (A-7)
U • yys
with n = 1. Complete hydrolysis of the 4 Ib/gal (3.4 mole/£) formulation with
8:1 (v/v) of 2N aqueous sodium hydroxide requires less than 1 minute. Con-
tainers should be thoroughly drained and rinsed with aqueous alkali (Section
3).
79
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A. 10 CHEMICAL METHODS FOR DETOXIFICATION OF DEF
Def is applied as a cotton defoliant. [t is marketed as a 6 lb/gai
c-muLsif table concentrate. Def is not water soluble, but is soluble in organic
solvents, including alcohols, chlorinated hydrocarbons, aliphatic and aromatic
hydrocarbons (8, 14, 15).
Def can be hydrolyzed in strong acid or base to yield non-toxic products,
but it is stable in the neutral pH range. Hydrolysis studies found in the
literature study have described techniques by which Def is degraded to butyl
mercaptan and phosphoric acid.
acid
3 n-CHSH + H
Russian workers have used nitric acid in combination with either silver nitrate
or hydrochloric acid (44). Alkaline conditions were also developed to exhaus-
tively hydrolyze Def (45, 46). Barber and Boyd describe exhaustive hydrolysis
of the analogous tributyl phosphorotrithioite, (n-C H S) P, which also apply to
Def hydrolysis (46, 47). The conditions require one-half hour reflux with a
1:1 mixture of isopropyl alcohol and 0.5N sodium hydroxide plus 0.5% of sodium
borohydride. No information was found which describe hydrolysis at ambient
temperature with concentrations of 5 to 10% sodium hydroxide. The Dt-f hydrol-
ysis to phosphoric acid .(and salts) and n-butyl mercaptan would be a suitabJe
detoxification. Oral LD5Q for rats was 1530 mg/kg and 682 mg/kg for the acid.
and mercaptan, respectively (4). The mercaptan does have an odor which is
objectionable (38), but the odor can be controlled with hypochlorite solution
(46); butyl mercaptan is probably converted to dibutyl sulfide (48).
80
-------
Available literature suggests that Def hydrolyzes slowly in 1-2N alkali
(15, 45). Although no suitable data was found for Def or analogous phosphoro-
trithioate esters, a lower limit reaction time can be speculated using data
for trimethylphosphate hydrolysis. Sulfur analogs are hydrolyzed more slowly
than corresponding phosphates (9, 10). Faust and Gomaa have indicated P=0
esters hydrolyze at a rate 5 times faster than P=S analogs (10). Steric
effects will result in slower hydrolysis for butyl esters than methyl esters
(48). It is estimated that Def will have a rate constant at least one order
of magnitude slower than trimethyl phosphate. Since the rate constant for
_3
trimethyl phosphate hydrolysis at 35°C is 0.330x10 £/mole-sec. (11), the
maximum rate for Def is estimated at 3x10 H/mole-sec. A lower limit for
t QQQ, 99.9% degradation time, was estimated from Equation A-7. Since the
U • s 7 J
dissociation constant, K , for HPO = hydrolysis to PO ~ is 2.2x10 £/mole,
the reaction stoichiometry is expected to fall between 2 and 3. So t _ ___
was calculated for n = 2 and 3. The hydrolysis conditions were 1:10 (vol/vol)
of
30H
PO = + H00 N HPO= + OH
4 2 v 4
6 Ib/gal Def (2.29 mole/A) reacted with 2N sodium hydroxide. The calculated
t 0 9g9 was about 50 hours for n = 3 and 44 hours for n = 2. These hydrolysis
times are judged too long for practical application.
Def should be disposed by a non-chemical alternative; the EPA recommended
procedures should be used (7a). The empty containers should be thoroughly drained
and rinsed by the NACA recommended method (Section 3) (7a).
81
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A. 11 CHEMICAL METHODS FOR DETOXIFICATION OF PENNCAP-M
PennCap-M is a microencapsulated formulation of methyl parathion. The
commercial product consists of an aqueous slurry of polyamide particles (30-50
urn average size) containing the active ingredient; the formulation contains
22.00% (2 Ib/gal) methyl parathion. The product is registered for use in a wide
variety of grains, fruits and vegetables, pasture, cotton and tobacco (49, 50).
Shih and Dal Porto have discussed salient information on physical and
chemical properties of methyl parathion and its solubility (1). Methyl parathion
is highly soluble in aromatic hydrocarbons and most organic solvents, but it is
only slightly soluble in aliphatic hydrocarbons and almost insoluble in water
(55-60 mg/£) (15). Table 25 summarizes the hydrolysis rate information des-
cribed in the Handbook (1).
Hydrolysis in water or alkaline medium yields 0,0-dimethylphosphorothioic
acid and _g-nitrophenol:
(CH30)2P-0-// \\ -N0 + H0 >• (CH0)POH + HO-
Shih and Dal Porto overestimated the toxicity of the products, when they claimed
that products were about as toxic as methyl parathion. They estimated environ-
mental hazard from intravenous LD,. of 10 mg/kg for rats, which was reportedly
listed in the Registry of Toxic Effects of Chemical Substances (4). (The
Registry actually lists intravenous LD of 10 mg/kg for dogs.) However, intra-
LjO
venous toxicity is not a fair estimate for environmental toxicity. A better
estimate is the oral LD of 350 mg/kg for rats (4). Since £-nitrophenol is
significantly less hazardous than methyl parathion (oral LD for rats is 9 mg/kg),
alkaline hydrolysis is suitable for chemical degradation.
-------
Table 25. Summary of Hydrolysis Data for Methyl Parathion.
Adapted from Shih and Dal Porto (1).
Solvent Temperature Hydrolysis Half-life
Water (pH 1-5) 20°C t^ = 175 days
0.01N NaOH 30°C t^ = 210 min.
l.ON NaOH 15 °C t| = 32 mln.
IN NaOH 20°C t, = 4.4 min.
T?
IN NaOH/acetone (1:1) 20°C t, = 10.7 min.
83
-------
M i croencapsula t i.on appears to have a minimal, effect on the chemi c.a I hydrol-
y:;i:; ol methyl paralhlou. Tin- c.t> I I wall docs not: consume hydroxide al a rate
CompeL f LJ.ve wilh the methyl parathion hydrolysis (51). Methyl parathlon appears
to leach rapidly and quantitatively from the micro-capsules. Karr evaluated
recovery of methyl parathion by its extraction with acetonitrile from the micro-
capsules (52). When cell walls were destroyed by grinding the capsules the
extraction recovered 100% of the methyl parathion. Without the grinding about
90-95% of methyl parathion was recovered. It is expected that 50% aqueous
ethanol is also a suitable medium for extracting the methyl parathion in PennCap-
M (51, 53).
Shih and Dal Porto discussed two other possibilities for methyl parathion
detoxification (1): reduction of the nitro group to yield the non-toxic 0,O-
dimethyl 0-p_-aminophenyl thiophosphate
-NO,
and oxidation to yield paraoxon:
(CH30)2P-0-
-NH,
?-0-
-NO,.
0
(CH30)2P-0-
-N0
Although they did not recommend either approach for detoxification, they did
suggest further study of methyl parathion reduction to the corresponding amine
as a possible method. The present study agrees with their conclusion that
neither procedure is suitable for detoxification. The reduction requires a very
corrosive acid (9:1 mixture of acetic and hydrochloric acid) and techniques
84
-------
which only a skilled chemist should attempt (54). Hsieh and coworkers have
evaluated alkaline sodium hypochlorite on parathion degradation (53). They
have found a significant increase in the degradation rate; their results are
detailed in Appendix F. Since the oxidation yields the more toxic methyl
paraoxon as an intermediate, it is not recommended.
Alkaline hydrolysis is proposed for decontaminating PennCap-M. Time for
99.9% degradation, t _ ni was calculated by Equation (A-7), based upon a
rate constant of 0.16 £/mole-min. and a 2:1 hydroxide-methyl parathion
stoichiometry:
S ___ S
ii // A _ ii
(CH 0) P-0-(/ \>-N00 + 20H
About 8:1 (vol/vol) of IN sodium hydroxide in 50% aqueous ethanol is suggested
for PennCap-M (0.91 moles/fc of methyl parathion); t _' « was calculated about
75 minutes for these conditions. Additional time should be allotted to
insure complete leaching of the methyl parathion from the microcapsules.
Alkaline rinse is suggested for empty containers (Section 3). Detoxifi-
cation of methyl parathion in rinsate is discussed in Appendix F.
85
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A. 12 CHEMICAL METHODS FOR DETOXIFICATION OF DYFONATE
Dyfonate is an insecticide applied for control of soil pests affecting a
wide variety of vegetables, grains, turf, sugarcane and sugarbeet, and tobacco.
It is available as an emulsified concentrate (4 Ibs/gal), granulars (5, 10, and
20% by weight), and dry bait (4% by weight). Dyfonate is miscible with organic
solvents; its water solubility is 13 ppm (14, 15, 55).
Dyfonate reacts with peroxides to yield a variety of products. Although
Stauffer Chemical Co. formerly recommended degradation with hypochlorite (2),
they no longer suggest this treatment (56). Although complete oxidation will
yield non-toxic products, partial oxidation will yield more toxic oxon inter-
mediate products (8, 43, 57). Six products have been identified from oxidation
by m-chloroperbenzoic acid. The major products are the corresponding phosphenyl
phenyl disulfide (20% to 30% yield) and the corresponding oxon (about 20%
yield); other products were phosphonic acid, phosphonothioic acid; sulfur, and
diphenyl disulfide (43, 57). The oral LD for Dyfonate is 16 mg/kg while for
the oxon it is 2.7 mg/kg (4).
Dyfonate hydrolyzes in aqueous base to yield the ethyl ester of ethyl
phosphonothioic acid and phenyl mercaptan (58). The phosphonothioate monoester
is expected to have low toxicity.
s
II
C H P 9P H -i- nn
^ J I D 5
. C2H5°
S
ii
w
+
,_
6 5
86
-------
I'henyl merc.aptan is toxic: oral '-D of 46 mg/kg for rats (4). Plumy I
mercaptan Ls readily converted with mJ Id clic-mical oxidants to djplicriyl dlsul-
fide, (C^Hc)0Sr, (48). Diphenyl disulfide appears much less toxic; the inter-
b j 2. 2.
peronital LD (for rats) is 100 mg/kg (4). Stronger oxidizing conditions
LiO
convert phenyl mercaptan to benzene sulfonic acid (oral LD of 890 mg/kg for
rats) (4, 48). Studies on the environmental fate for Dyfonate indicate that
phenyl mercaptan is a fugitive in soil. It rapidly metabolizes to simple low
hazard derivatives such as methyl phenyl sulfide (56).
Although alkaline hydrolysis appears to reduce the toxicity of Dyfonate,
insufficient data are available to suggest a practical method. An alternative
non-chemical method should be used for disposal; the EPA recommended proce-
dures should be followed (la). Empty containers should be thoroughly drained
and triple-rinsed by the NACA recommended method (Section 3).
87
-------
88
-------
APPENDIX B.
CHEMICAL METHODS FOR THE DETOXIFICATION OF
NITROGEN-CONTAINING PESTICIDES
B.I GENERAL REVIEW OF APPLICABLE DISPOSAL METHODS
The nitrogen-conlaining pesticides encompass a broader range of commercial
applications, toxicological properties, and physical and chemical behavior than
seen in the organophosphate pesticides. The variety of uses include insec-
ticides, herbicides, fungicides, plant growth regulators and fumigants. Table
26 presents the selected nitrogen-containing pesticides and their structures.
These pesticides represent twelve subdivisions based upon chemical structure.
For facilitation of general discussion these pesticides can be designated
X
either as carbonyl (or carbamoyl) ' where X is oxygen or sulfur, or
"L*™"
"other." The first group includes carbamates, thiocarbamates, dithiocarbam-
ates, anilides, imides and hydrazides, amides, and ureas and uracils. All of
these can be hydrolyzed. Their kinetic behavior follows the same scheme as
the phosphates (Equations A2-11). Unlike the phosphates the hydrolysis does
not almost always affect toxicity. Only the carbamates as a class are acetyl-
cholinesterase inhibitors which can be detoxified by hydrolysis. The "other"
group of nitrogen-containing pesticides encompasses the amines (including the
triazenes, heterocyclic amines, and quarternary ammonium compounds), the
nitre-compounds and miscellaneous group.
89
-------
Table 26. Chemical Structures of Selected Nitrogen-Containing Pesticides
Class
Pesticide Name
Common
Trade
Structure
Molecular Weight
Cg)
Carbamates
0.
-OC*N-
Carbofuran Furadan
ru
CH
Aldicarb Temik
OCNHCH,.
6' 3
CH- 0
I 3 I!
CH»SCCH=NOCNHCHQ
J i ->
221.3
190.3
Thiocarbamates
Methomyl Lannate, Nudrin
EPIC
Eptam
CH SC=NOCNHCH
S 0
II | il I
-OCN- or -SCN-
0
II
CH CH SCN(n-C H )
162.2
.189.3
Molinate Ordram
CK3CH SCN
187.3
-------
Table 26. Chemical Structures of Selected Nitrogen-Containing Pesticides (Cont'd.)
Class
Pesticide Name
Common
Trade
Structure
Molecular Weight
(g)
Dithiocarbamates
S
il I
-SCN-
Thiram
SS
(CH3)2NCCH(CH3)2
240.4
Anilides
i li i
Aryl-N-C-C-
Propanil
C\
0
II
,— NHCCH,
218.1
Iraides and Hydrazides
0 0
ii i M
-CN-X where X = C- or NR R
Captafol
Amides
NSCC12CHC12
349.1
Diphenamid
0
2CHCN(CH3)2
239.3
-------
Table 26. Chemical Structures of Selected Nitrogen-Containing Pesticides (Cont'd.)
Class
Pesticide Name
Common
Trade
Structure
Molecular Weight
(g)
Ureas and Uracils
0
Hi
-NHCN-
Triazenes
Chloroxuron
Cl
/"Vo
Cyanazine Bladex
Simazine
0
II
NHCN(CH
A
-N IT N-
l(
^. NC(CH ) CN
Cl
290.7
240.7
201.7
Heterocyclic Amines
Aminotriazole Amitrole
S4.1
-------
Table 26. Chemical Structures of Selected Nitrogen-Containing Pesticides (Cont'd.)
Class
Pesticide Name
Common Trade
Structure
Molecular Weight
(g)
Quaternary Ammonium Compounds
Paraquat
(as Paraquat
dichloride)
CH.
-CH,
Cl,
186.3
(257.2)
Aromatic Nitro Compounds
PCNB
Terrachlor
U>
Cl
>H
Dinoseb
NO,
295.4
240.2
Other Nitrogen-Containing Compounds
Chloropicrin
C13CN°2
164.
-------
I'../ CIIKMICAI. MKTIIODS I-'OK DIvTOX I !•'I CAT I ON ()!•' CAKKORIKAN
Ca rbo I n ran ( KM radan) is a broad band insecticide;, mil icidc and ncinal oc i de ,
which Ls applied to field crops, grains, cotton and tobacco. Solubility is
700 ppm in water, 4% (W/W) in ethanol and in benzene, and 15% in acetone. It
is available as a 4 Ib/gal flowable and granule (2, 3, 5 and 10%) (14, 16, 59).
The chemical behavior of carbofuran is analogous to carbaryl, which Shih
and Dal Porto reviewed (1). While carbofuran is relatively stable in acid and
neutral media, it hydrolyzes in alkali to yield methylamine, carbonate, and 2,2-
dimethyl-2,3-dihydrobenzofuran-7-ol (60).
+ 3 OH"
CH_NHr
Carbonate is non-toxic and methylamine has subcutaneous LD of 2500 mg/kg for
J_jO
mice (4). The benzofuranol appears stable in strong alkali. No information
was available on its toxicity, its environmental fate, or the toxicity of its
metabolites. Metabolic studies of carbofuran suggest that the benzofuranol
might be oxidized to 3-hydroxy- and 3-keto-derivatives (60, 61). Although the
toxicities of the benzofuranol and its potential metabolites are not known,
they are expected to be on the same order as a-naphthol, which is the hydrol-
ysis product of carbaryl (1).
Metcalf and coworkers studied hydrolysis kinetics for 0.1% (w/v) carbo-
furan in methanol in a pH 9.5 buffer (62). The pseudo first-order rate con-
-2 -1 3
stant was 1.04x10 min which yields a bimolecular rate constant of 3.35x10
St/mole-min (from Equation A-ll). The rate constant for 25°C was calculated by
the Arrhenius relationship (Equation A-9) assuming that the activation energy,
94
-------
E = 20 kcal/mole, is about the same for alkaline hydrolysis of carbofuran and
rarbary I. (I). This y I».' I di-d a b Imo ler.u lar rail- i:on.sLunl oi I/O V./mp I I'-mi n .
Tills value- Is .similar Lo Liu-. raL«.- c.uiisLanl lor '(AO C./mo l.i:-mlu lor carl>aryl
hydrolysis at 25°C (1), which is expected since the two have similar chemical
structures.
A decontaminant solution of sodium hydroxide in 50% aqueous ethanol is
recommended to achieve sufficient carbofuran dissolution. t _ QC>C., 99.9%
\J • -7 j "
degradation time was calculated by Equation A-7 with n = 3 (3:1 hydroxide-
carbofuran stoichiometry). For the 4 Ib/gal flowable formulation t „ qqq was
calculated as less than 1 minute with 20:1 (v/v) IN NaOH or 10:1 (v/v) 2N
NaOH. Additional time is suggested for granular formulations to allow the
carbofuran to desorb. The 10%, 5%, and 2% formulations (0.2, 0.1, and 0.05
moles/lb, respectively), can also be detoxified with IN NaOH in 50% aqueous
ethanol.
Bags should be thoroughly emptied and disposed according to the EPA
recommended procedures (7a). Empty containers should be drained thoroughly
and triple rinsed with the aqueous ethanolic alkaline decontaminant or water,
if the rinsate could be used for dilution (Section 3).
95
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M.'l CIIKMICAI. Mrmons l-'()l< DKTOX I I'11 CAT I ON OK AI.DICAKh
Aldic.'irb is ,i ;;ys I (.'in i c , soil applied insecticide'. IU'caiis<' ol its very h i )'.h
acuLu Loxic.ity, Lt is only .marketed as a granular formulation. It js available
as 5, 10, or 15% active ingredients and in 10 and 25 Ib bags. Aldicarb is
applied to a broad range of crops and ornamentals (14, 63). It is soluble in
chlorinated hydrocarbons, ketones and aromatic hydrocarbons. Water solubility
is 6 g/£ at 30°C. Aldicarb can rapidly be oxidized to its sulfoxide and then
more slowly to the sulfone. The sulfoxide is very water soluble (more than 33%)
(15).
Aldicarb?s hydrolysis behavior is typical for carbamates. It is stable in
neutral media, but hydrolyzes in acid and base. It is most rapidly hydrolyzed
by base (60, 63). Alkaline hydrolysis yields £-methyl-3-thiomethylpropionalde-
hyde oxime, methylamine, and carbonate (64, 65):
0
ii
CH SC(CH ) CH=NOCNHCH
20H~
CH SC-CH=NOH
3 i
CH,,
CH0NH0
32
CC)
The oxime appears to be relatively stable in base. A minor component of the
alkaline hydrolysis is the dehydration product, the corresponding nitrile (66).
The oxime is hydrolyzed in acidic media to yield the aldehyde and hydroxylamine
(64, 65).
H
The hydrolysis products have a lower acute hazard than aldicarb. Methyl-
amine has a relatively low hazard. Oral LD (rats) for the oxime is 0.77 ml/kg
Qfi
-------
(66). No information was available for the corresponding aldehyde. Since the
oxime's acute toxicity is low, it is reasonable to expect that the aldehyde
toxicity is also low. Since hydroxylamine and some of its derivatives are
suspected mutagens (67), the oxime is also suspect. Hydrolysis of the oxime
to yield the aldehyde is a better procedure, but it would require greater
technical skills and time commitment than could be expected of the layman.
Oxidants such as peracidic acid convert the sulfur group in aldicarb to
the corresponding sulfoxide and sulfone (60, 68). The oxidation does not
significantly alter toxicity: oral LD for rats is 0.9 and 25 mg/kg for the
sulfoxide and sulfone, respectively. The hydrolysis is faster for the oxi-
dized analogs. Comparative hydrolysis data are summarized in Table 27.
Metabolic oxidation also produces the sulfoxide and sulfone (61, 63).
Table 27. Half-lives for Aldicarb and Oxidized Derivative
Hydrolysis in Water (69)
Product
Aldicarb
Aldicarb sulfoxide
Aldicarb sulfone
£H
6
7
8
6
7
8
6
7
8
Half-life
80°C
1140
205
49
80
45
3
120
15
1.5
(minutes)
110°C
115
54
7
20
8
0.5
50
< 1
< 0.5
97
-------
The time for 99.9% degradation was calculated with Equation (A-7) with a
_2
rate constant, k, of 1.2x10 £/mole-min. for aldicarb hydrolysis in 50%
aqueous etlianol at ambient temperature- (63). The stoichiometry of the alka-
line hydrolysis requires a minimum hydroxide-aldicarb of 2:1.; additional base
might be consumed by the oxime, which is a weak acid (48):
CH3SC(CH3)2CH=NOH + OH ^ CH SC(CH ) CH=NO + HO
Table 28 summarizes results and compares t for the various formulations
u • y y y
hydrolyzed by IN and 2N hydroxide. Better hydrolysis times were obtained for
2N NaOH decontaminant solutions, and it is recommended for use. Since the
pesticide must dissolve in order to be hydrolyzed in the calculated time,
overnight contact is suggested to allow for desorption.
Bags should be thoroughly emptied before disposal. They should be dis-
posed by the EPA recommended procedures (Section 3) (7a).
98
-------
Table 28. Calculated Time for 99.9% Degradation of Aldicarb
in 50% Aqueous Ethanol at Ambient Temperature
C0.999
Aldicarb
Formulation (moles/lb) n = 2 n = 3
15% 0.36 13.9a 18.5a
5.7b 6.3b
5.2C 5.4°
10% 0.24 11.8a 13.9a
5.4b 5.7b
5% 0.12 10.7a 11.33
5.1b 5.2b
(a) 2 liters of IN NaOH/pound granular formulation
(b) 2 liters of 2N NaOH/pound granular formulation
(c) 4 liters of IN NaOH/pound granular formulation
99
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II./i CHEMICAL METHODS FOK DETOX I !•' I CAT I UN OK MKTHOMYI,
McChomy I (l.-i nn.i I c , Nu|> I i cd I'or Insects aiicl iicinal.ocli'.s conlro.l in
.1 broad range ol" ve};rlables, fruits, Iie.lcl crops and ornamentals. IL Is f'onmi-
lated as a 90% water soluble powder, 24% emulsifiable concentrate (1.8 Ibs/gal),
and 2% and 5% dust. Methomyl is water soluble (58 g/£) and is very soluble in
alcohols and aromatic solvents (14, 15, 70).
Methomyl's chemical reactivity is similar in some respects to aldicarb
(Appendix B.3). Its hydrolysis parallels aldicarb, but it appears more resis-
tant to oxidation (71). Methomyl hydrolysis is fastest in alkaline media (60).
Alkaline hydrolysis products are dimethylamine, carbonate and methyl-N-hydroxy-
thioacetimidate (72).
CHS y _ CH S
J^C=NOCNHCH3 + 20H > C=NOH
CH3 CH -
The oxime appears resistant to hydrolysis. Carbonate and methylamine are non-
toxic (4). The oxime has a lower acute toxicity than methomyl, which is an
acetylcholinesterase inhibitor (71). Oximes as a class are suspected carcino-
gens (67). Feeding studies with rats have shown no apparent chronic effects for
methomyl (72). Since the oxime is a methomyl metabolite, the oxime is also
expected to show no chronic effect (72, 73).
Relatively little information was found to describe kinetics. The only
useable data was a report on methomyl degradation at aqueous pH 9.1, Table 29.
Details of the study were not available (70, 71).
100
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Table 29. Degradation of Methomyl in Water at pH 9.1 (70).
Time in Percent Methomyl Loss
Solution 8 oz/100 gal 16 oz/100 gal
0 0 0
4 hrs 4 3
6 hrs 5 3
24 hrs 11 8
2 days 18 13
3 days 22 18
6 days 39 30
101
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A rate constant was calculated for 39% degradation at 6 days and assuming
that the hydrolysis was pseudo-first order (hydroxide concentration remains
constant). Using Equations (A-6 and 11) the rate constant, k, was calculated
as 4.17 £/mole-hour. This is about two orders of magnitude faster than for
aldicarb. Time for 99.9% degradation, t QQQ> was calculated from Equation
u • y y,/
(A-7). Stoichiometry for methomyl hydrolysis is the same as for aldicarb; n
is expected to be slightly above 2.
Since methomyl is relatively water soluble, aqueous 2N sodium hydroxide
is considered a suitable decontaminant. t qqq» 99% degradation time, was
calculated as 1.4 hours for the flowable formulation with 5:1 (v/v) ratio of
decontaminant to pesticide; 1.3 hours for the 90% soluble powder with 3.72.
decontaminant per pound; and 1.2 hours or less for the 2% and 5% dusts with 1£
decontaminant per pound.
Empty containers should be thoroughly drained and then rinsed with an
alkaline decontaminant or water if the rinsate could be used for dilution.
Bags should be thoroughly emptied and then disposed as the EPA has recommended
(Section 3).
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15.5 CHEMICAL MKTHODS FOR DETOXIFICATION OF F.PTC
KFl'C (Kptam) is a preumer^enL herbicide u.sed to control annual and peren-
nial weeds for numerous field crops. Ll is primarily marketed as a 7 Ifo/gal
emulsifiable concentrate. Eptam is raiscible in all proportions with acetone,
methanol and aromatic solvents, and soluble in most organic solvents. Aqueous
solubility is 365 ppm at 20°C (14, 75, 76). Eptam has a low toxicity for rats
and mice (oral LD of 1630 and 750, respectively) but is moderately toxic for
cats (112 mg/kg) (4).
EPIC can be hydrolyzed to di-n-propylamine, ethyl mercaptan and CO- (or
carbonate) (45, 76). The hydrolysis products are more toxic to rats than
EPTC; oral LD values are 930 and 682 mg/kg for di-n-propylamine and ethyl
mercaptan, respectively (4). EPTC does have moderate aquatic toxicity (Table
6); no information on aquatic toxicities of the hydrolysis products was found.
EPTC hydrolysis is very slow in dilute acid or base. Less than 5% hydrolyzed
after 300 days at 20°C in 0.1N H SO HC1 or NaOH. It hydrolyzes completely
after heating at 85°C for 10 minutes in 96% sulfuric acid (45). This strong
acid is only suitable for use by trained personnel.
EPTC can be oxidized to yield di-n-propylamine and ethanesulfonic acid
(28). Di-n-propylamine (oral LD of 930 mg/kg for rats) is non-toxic. No
toxicity information was found for ethanesulfonic acid (4). The reaction
conditions and degradation times were not available.
Since no acceptable chemical detoxification is available, EPTC should be
disposed by the EPA recommended, alternative procedures (7a). . Empty containers
should be thoroughly drained then disposed by the EPA recommended procedures
(Section 3).
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U.(, CIIKMICAI. MKTHODS KOR DI'VI'OX I V I CAT I ON OF MOM NATK
MII I i.n.-ii r Is a si' I IT t I. vi- herb I c id*1 for l>roatl I eaved and grassy weeds. I I.
i s rrcoinimMidtuI Tor control of watergrass in rice. It is soluble at 800 ppm in
water, but is miscible in all proportions with kerosene, ketones, xylene and
toluene. It is formulated as 10% granules and an 8 Ib/gal emulsifiable con-
centrate (14, 15, 78).
Molinate is relatively resistant to hydrolysis. It will hydrolyze in
strong acid (96% sulfuric acid) to yield hexamethylenimine (hexahydro-lH
azepine) (18). Hexamethylenimine, which has an oral LD of 33 mg/kg for
rats, is more toxic than molinate (oral LD of 501 mg/kg for rats) (4). No
other information was found for the chemistry of molinate.
Molinate should be disposed by a non-chemical, alternative method as
recommended by the EPA (7a). Bags should be thoroughly emptied and bottles
and drums should be thoroughly drained and triple rinsed by the NACA recom-
mended procedure (Section 3).
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B.7 CHEMICAL METHODS FOR DETOXIFICATION OF THIRAM
Thiram is applied as a seed treatment and a fungicide for turf, shrubs and
ornamentals, fruit trees, and vegetables. Thiram solubility is low in water (30
ppm) and relatively low in methanol and ethanol ( <1 g/100 ml). It is slightly
soluble in carbon tetrachloride and xylene; moderately soluble in benzene,
dioxane, and ketones; and soluble (230 g/&) in chloroform. Thiram is formulated
in a wide variety of products, often in combination with other pesticides.
Formulations include dusts and wettable powders containing 50 to 75% active
ingredients and 42% liquid suspension (4 Ib/gal) (14, 15, 79).
Thiram is a member of the thiuram family, whose common structural unit is
disulfide bonded to carbamoyl groups.
S S
n n
-NC-SS-CN-
The thiuram structure reacts by redox (oxidation-reduction) and ionic mechanisms.
Its chemistry has been extensively reviewed by Thorn and Ludwig (80).
When thiram is refluxed with acetic acid or acetic anhydride, it yields
CS , COS, and dimethylamine. Several products are formed when thiram is refluxed
with acetone; those identified include dimethylamine, CS , and three products of
dimethylcarbomyl bonded to acetone. Thiram reacts with cyanide ion to yield the
mpnosulfide and thiocyanate. Thiram reacts with dimethylamine in benzene at 50°
to form an ammonium salt and sulfenamide; product toxicity is unknown.
S S S S
(CH3)2NCSSCN(CH3)2
105
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'I'll i rani is reduced l>y several metals and mi-La I rom|> I c-xes , I nc. 1 ud I ii)-. /. inr,
romper and Cu(l) sall.s, Lo yield metul sa.lLs of il Imelhyld i Lli locarl>am i <•. add.
Although these salts have low oral toxicities, some of these salts also have
shown positive carcinogenic effects, for example, the zinc salt (Ziram) (4).
Acid treatment of these salts degrades them and yields carbon disulfide and
dimethylamine (80, 81). Other reducing agents, such as sulfide and bisulfite
also cleave the thiuram disulfide; treatment with H S can directly reduce
thiram to dimethylamine and carbon disulfide.
Thiram reduction is not suitable for general use. Dimethylamine is
slightly toxic (oral LD,. = 698 mg/kg for rats). Although carbon disulfide
has a relatively low acute toxicity, it is a relatively low boiling material
(46.1°C) with a strong, disagreeable odor and is inflammable (38). Because
thiram has a relatively low solubility in water, alcohol, or ketones, the
reduction will require either reflux with these solvents or use of chloroform
or a comparable organic solvent. The reagents and reaction conditions require
technical skills too advanced for general use.
Waste thiram should be disposed as described by the EPA (la). Bags
should be thoroughly emptied before disposal. Empty bottles and drums should
be thoroughly drained and triple rinsed by the NACA recommended method (Section
3).
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B.8 CHEMICAL METHODS FOR DETOXIFICATION OF PROPANIL
Propanil is applied as a post-emergent herbicide to control grasses and
weeds. It is formulated as a 35% emulsifiable concentrate (3 Ib/gal) (15, 82,
83). It has a low water solubility (20 mg/100 ml) and is very soluble in
methanol, benzene, and acetone (15, 45).
Propanil is hydrolyzed by acid or base to yield propanoic acid and 3,4-
dichloroaniline (15,. 45). 3,4-Dichloroaniline (oral LD = 648 mg/kg) is only
slightly less toxic to rats than propanil (oral LD,-n = 560 mg/kg) (4). Soil
microorganisms metabolize propanil to 2,4-dichloroaniline which further
metabolizes to chloroazobenzene. Products are very persistent in the soil
(84).
Propanil should be disposed by a non-chemical alternative as described
by the EPA (7a). Rohm and Haas suggest diluting propanil with a flammable
solvent and incineration (82). Empty containers should be thoroughly drained
and triple rinsed by the NACA recommended method (Section 3).
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B.9 CHEMICAL METHODS FOR DETOXIFICATION OF CAPTAFOL
Captafol (Difoltan) is a broad spectrum fungicide for control of economic
diseases of fruits, vegetables, ornamentals, and turf grasses. It is also
applied for seed and soil treatment (14, 15, 85). Captafol is available as an
80% wettable powder, a 4 Ib/gal flowable and in several formulations for seed
treatment. Captafol is practically water insoluble (1.4 ppm), moderately
soluble in acetone (4.3 g/100 ml) and slightly soluble in alcohols (18, 85).
Captafol is similar in physical and chemical properties to the fungicide
captan, which Shih and Dal Porto reviewed (1). They recommended alkaline
detoxification:
NSCC13 || I yNSCCl2CHCl2
Captafol is relatively stable in acid and neutral conditions, but hydrolyzes
rapidly in alkali (15, 18, 86). Wolfe and coworkers have compared hydrolysis
rates of captan and captafol. At 28°C pseudo-first order rate constants were
6.5xlO~5 sec"1 (pH 7.07) and 7.07xlO~5 sec"1 (pH 7.17), respectively (87).
Equation (B-l) describes the pH dependence of the pseudo-first order rate
constant k, in buffer:
This expression is expected for the alkaline region of Equation (A-2). A rate
constant for alkaline hydrolysis of captafol was estimated by assuming that
captafol and captan have similar rate constants at all alkaline pH and that the
108
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water hydrolysis rate, k^ , is small. Since captan hydrolysis rate is
2
-3 -1
1.1x10 sec at pH 8.25 and 28°C, the second-order rate for captafol is
4
estimated as 1.17x10 £/mole-min.
The hydrolysis stoichiometry is not certain. Captafol is hydrolyzed by
alkali to tetrahydrophthalimide, hydrogen chloride, dichloroacetic acid and
various oxidation states of sulfur (28, 86, 87).
0 0
u
*SCC12CHC12 + 3 OH~ »• f| II NH + 2 Cl~ + CHC^CO" + [s]
The minimum hydroxide captafol ratio necessary for complete hydrolysis is 3.
However, additional demands for hydroxide can result in a higher value. Al-
though the imide and dichloroacetic acid can hydrolyze further to ultimately
yield ammonia and cyclohex-2-ene-l,2-dicarboxylic acid, rates are slow and it
is not a practical concern (86). However, the imide which is a weak acid (48)
and any sulfur present as hydrogen sulfide will require hydroxide for neutral-
ization. To insure sufficient hydroxide for hydrolysis, a minimum ratio 10:1
hydroxide to captafol is recommended. Time for 99.9% degradation, t goo*
was calculated with Equation (A-7). t' qqq is less than 1 minute with a 10:1
molar excess of base, even with n as high as 6.
The hydrolysis products are not fungicidally active (1). Sodium chloro-
acetate (intravenous LD = 1880 mg/kg for mice), chloride, and carbonate are
non-toxic (4). Sulfides are moderately toxic but are not considered a serious
hazard in alkaline media (38). Tetrahydrophthalidimide is not an acute toxi-
cant, but it has shown teratogenic effects with hamsters (4). Empty containers
109
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should be thoroughly drained before disposal. Empty bottles and drums should
bi- thoroughly drained and rJnst-d (Section '5). Empty bags should he disposed
riH recommended by the EPA (la).
110
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li.K) CllliMICAI. MKTIIODS KOK DKTOX I !•'ICATION ()!• I) I I'MKNAMI L>
I) i |)licinainid Ls a st-leu: live pre-emer^i'iice ln-rh lc. i cle for control <>l .mim.il
grasses and broadleaf weeds in field crops, Cruit shrubs and trees, ornamcMitals
and lawns. It has a low water solubility (260 ppm at 25°C) but is soluble in
acetone and xylene. It is formulated as 50% and 80% wettable powder, 5%
granule and, 4 Ib/gal liquid dispersant (1A, 15).
The Diphenamid toxicity reported in the Registry of Toxic Effects of Chem-
ical Substances (oral LD of 293 rag/kg for rats) might overstate the hazard
(4, 88). This value was derived in a study with newborn rats. The Upjohn
Company used adult rats in toxicity tests and obtained an oral LD greater
than 1000 mg/kg (88).
Diphenamid is relatively resistant to hydrolysis by acid or base. Holden
and coworkers evaluated hydrolysis in 0.5N potassium hydroxide at 40°C (89).
The hydrolysis products are diphenylacetic acid and dimethylamine. They
detected less than 4% dimethylamine after 30 minutes. Although the hydrolysis
products are less phytotoxic, the hydrolysis is too slow for practical use.
Small quantities of Diphenamid can be disposed by the EPA recommended
procedures as an alternative to chemical detoxification. Sacks should be
thoroughly emptied then disposed by the EPA recommended procedures. Empty
bottles and drums should be thoroughly drained and triple rinsed by the NACA
recommended method (Section 3) (7a).
Ill
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B.ll. CHEMICAL METHODS FOR DETOXIFICATION OF CHLOROXURON
Cliloroxuron (Tenoran) is a herbicido u.sed primarily as u post -erne rgi'iice
lie rb i c ul i- for annual broad leaf s and also a small use as a pre-emerj.'.t.-tit herbi-
cide. It has a low water solubility (3.7 ppm at 20°C) , is slightly soluble in
alcohol, and is very soluble in acetone. It is formulated as a 50% wettable
powder and 5% granular (15, 90).
Chloroxuron is hydrolyzed by strong acids or bases to p_-(p_-chlorophenoxyl)
aniline, dime thy lamine and carbon dioxide (90):
acid
NHCON(CH,)
0 + (CH,)_NH + C00
2 32 /
Although aqueous hydrolysis rates were not given Cor chloroxuron, based upon
information available for hydrolysis of other area pesticides its hydrolysis
rate is expected to be slow. Carbon dioxide is non-toxic and dimethylamine is
slightly toxic (oral LD = 698 mg/kg for rats) (4).
The toxicity of the aniline was not found by literature search. Since
several anilines are carcinogenic, the j>-(£-chlorophenoxy) aniline is also
suspect (4, 67).
A few other reactions of the ureas are known, l>uL none of l.licm .in- prtu--
tical disposal methods. Heating chloroxuron in water results in cross-amina-
tion (90).
112
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Chloroxuron must be disposed by alternative, non-chemJcal procedures as
recommended by the EPA (7a). Bags should be thoroughly emptied and disposed
by the EPA recommended procedures (Section 3) (7a).
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15.12 CHEMICAL METHODS FOR DETOXIFICATION OF S1MAZ1NE
Simazine (Princep) is a selective and broad band pre-emergent herbicide.
Its solubility is low in water (5 ppm) , methanol (400 ppm) and chloroform (900
ppm) . Its formulations include 50% and 80% wettable powder, and 4% and 8%
granules (15, 45).
Simazine has the characteristic physical and chemical properties of the
js-triazene herbicides. This group has been extensively reviewed (90, 92);
also Shih and Dal Porto (1) reviewed the analogous atrazine.
Cl
N-^VVN
25 NHCH(CH3)2 C2H
Atrazine Simazine
Simazine is relatively non-toxic but is environmentally persistent. It is
metabolized in soil to hydroxysimazine, which is not herbicidally active.
Cl OH
Simazine, like other j3-triazenes, can be chemically hydrolized. Shih and
Dal Porto (1) adopted a chemical hydrolysis procedure for atrazine detoxification.
The kinetic behavior of the j3-triazenes parallel the organophosphates and
carbamate pesticides (90, '92). Hydrolysis rate follows a bell-shaped pH profile.
The rate is slowest in the central pH range and most rapid at pH extremes.
Kinetic arguments in Appendix A can be applied to the s-triazenes (93). The
114
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kinetic scheme requires homogeneous solution of pesticide. Shih and Dai Porto
calculated the 99.9% degradation time, t , for atrazine hydrolysis at
ambient temperature and pH 14 (1). However, since a number of their assumptions
were wrong, their estimated t _ of 4.5 hours underestimates the required
degradation time. Perhaps the most serious error was that the hydrolysis
scheme uses an atrazine concentration very much higher than its aqueous solu-
bility (93). There is no way to calculate the actual time required.
Simazine should be disposed by a non-chemical alternative as described
in the EPA recommendations (7a). Empty containers should also be disposed by
these recommendations (Section 3).
If simazine is to be disposed by land burial, mixture with lime (calcium
hydroxide) could facilitate degradation. s-triazines are chemically hydrol-
yzed by acid or base at rates which are soil catalyzed (94). Lime is pre-
ferred to a strong acid, since it is solid, and relatively easy to handle.
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li.li CIIKMICAI. MKTIIODS KOK DliTOX I KI CAT I ON OK CYANAZINK
Cy.in.-i/. i ML' (llhidcx) is ;i pre- and posL-einerge.nce herbicide used lor l>ro;id-
le.nved weeds and annual grasses. It has a low water solubility (191 ppm) and
is ethanol soluble (45 g/£). It is formulated as a 4 Ib/gal water dispersible
suspension, 80% wettable powder and 15% granule (14, 15).
Cyanazine's oral toxicity (LD = 340 mg/kg for rats) is more hazardous
than for other triazenes which have oral LD values of 1000 mg/kg or more
(2). This higher toxicity apparently results from the cyanide group, so it
was anticipated that hydrolysis would reduce oral toxicity. However, infor-
mation concerning chemical hydrolysis and toxicity of hydrolysis products is
restricted as proprietary information (95). Lau and coworkers have reported
that cyanazine is metabolized in soil by a series of hydrolyses (96). It is
expected that chemical hydrolysis parallels metabolic hydrolysis by yielding
identical intermediate products in a series of hydrolysis steps.
Cl Cl
N"
9
NHC(CH3)2CN ^ N
Cl OH
N'
0 II A 0
lie
-------
The hydroxy acid derivative can l>e further degraded to S, 5-dimetliy lliydanto in
l>y hi';it i ii}'. il with ;i mixture ol I IT r i <-y;ni i di- ;ind sodium ;ici-l ;i I i: in c.l.ici.il
.'icel I c ;ic I (I .
OH
0
CH,
/^ s°
N ^N »- H-N f
IN^ S ^,*
C7H HN ^" ' NHC(CH ) COH u V CH,
•^ o / H 3
Cyanazine should be disposed by an EPA recommended procedure (7a). Empty
bottles and drums should be rinsed by NACA recommended procedures (Section 3).
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B.14 CHEMICAL METHODS FOR DETOXIFICATION OF AMITROLE
Amitrole (3-amino-s-triazole) is a non-selective systemic herbicide used
t:o control grasses and broadleaf weeds, poison ivy, and aquatic weeds; it is
nor. applied to crops (14, 15). It is formulated as a 50% soluble powder and a
2 Ib/gal liquid (97). Amitrole is highly water soluble (28 g/100 g at 23°C) ,
less soluble in ethanol, and insoluble in nonpolar solvents (14, 15).
Amitrole exhibits the chemical behavior of an aromatic amine (98). It is
stable toward hydrolysis and oxidation. The amine group (-NH ) forms salts
with acids, Schiff bases with aldehydes and ketones, amides from acyl chlorides
and anhydrides, diazonium salts, and metal complexes. Product toxicities were
not found. The triazole ring could be opened through reactions with methyl
iodide. None of these reactions are practical detoxification approaches.
Amitrole is relatively non-persistent; half-lives are reported at 1.0 and
1.5 month at 30° and 15°C, respectively (92). However, it is transported very
quickly with ground water (99).
Amitrole should be disposed by an EPA recommended alternative to chemical
detoxification (la). It is sold in cardboard containers (soluble powder) and
5 gallon plastic bottles (liquid). The empty bottles should be triple rinsed
by the NACA recommended method. Cardboard containers should be disposed by
an EPA recommended method (Section 3).
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B.15 CHEMICAL METHODS FOR DETOXIFICATION OF PARAQUAT
Paraquat is a quick acting herbicide and dessicant for weed and grass
eradication before seeding; for weed control in orchards, shade trees and
ornamentals; for industrial and roadside vegetation control; and for desicca-
tion and defoliation of cotton. Paraquat is formulated as a 2 Ib/gal soluble
concentrate (15, 100).
Paraquat is the l,l'-dimethyl-4,4'-bipyridinium dication. It is most
commonly marketed as the dichloride salt but sometimes is available with other
anions, such as methylsulfate. The anion is neither important for paraquat
activity nor its detoxification. Paraquat is water soluble and slightly sol-
uble in low-molecular weight alcohols (18, 100).
While paraquat is stable in acid and neutral media, it is hydrolyzed by
base to yield an ill-defined resinous product (18). It was reportedly not
affected by 100% methanolamine but was degraded by metallic sodium or lithium
in liquid ammonia (99.9%) or sodium biphenyl (95%) (lOOa). Paraquat hydroly-
sis reportedly requires pH greater than 12 (lOOb). No information is avail-
able on the product composition or toxicity. Lawless and coworkers suggest
hydrolysis with household detergent and burial of the product in clay soil for
disposal (2). Because product fate in soil as well as product toxicity is
unknown, the present study does not recommend paraquat hydrolysis for detoxi-
fication.
Paraquat reacts by chemical oxidation and reduction. With weak reducing
systems it forms a stable free radical which can be reoxidized to paraquat
with atmospheric oxygen. Strong reducing systems reduce it to 1-methylpiperi-
dine (18).
119
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Sfv«'r;i I oxid.nils will di'j>,r;idr |>;ir:i<|ii.'i( . (!.i I dc-rh.'ink (101) li;is described
il.s oxidiiLion by ;i J.ku I. i.nt>. 1 i;rr icyanidi- :ind by hydrogen peroxide. Tin- milder
nxidant, ferricyanide, yields the monopyridone and dipyridone. Oxidation
with hydrogen peroxide yields these same products as well as the 4-carboxy-l-
methylpyridinium ion. The pyridone and dipyridone appear to be further oxi-
dized to yield a product tentatively identified as 4-carboxy-l-methyl-2-
pyridone. With strong oxidizing conditions hydrogen peroxides oxidized
paraquat to oxalic acid. No information was found to describe toxicity of any
products except oxalic acid (sodium oxalate has a subcutaneous LD of 100 mg/
1_*O
kg for mice) (A). Also, reaction conditions are not available.
Faust and Gomaa have examined paraquat oxidation with permanganate,
chlorine dioxide, and hypochlorite (102). While they did not perform a com-
plete product study, they speculated that final products consisted of ammonia
and either carbon dioxide (oxidation in acidic media) or oxylate (oxidation in
alkaline media). These assigned products are non-toxic (A). Their assumption
regarding products is probably valid for very strong oxidizing conditions.
120
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The oxidation with permanganate yields MnO ; the Registry (4) lists its
toxicity as L.D = 45 mg/kg (intervenous) for rabbits.
LjO
Oxidation was fastest in alkaline media. CIO oxidation was too fast
to measure in the pH range 8.14 to 10.15. With aqueous chlorine (HOCl) and
permanganate the oxidation was rapid, but could be measured. The observed
second order rate constants (at 20° and in pH buffers) were for permanganate
-1 -1 -3 -2
6.56 i/mole min at pH 9.13 and for aqueous chlorine 5.75x10 , 1.70x10
and 3.02xlO~2 «,/mole~1min~1 at pH8.14, 9.04, and 10.13, respectively. The
complete oxidation requires very large volumes of oxidant for completion:
stoichiometers are
(C H N ) + 14 MnO, -• -> 14 Mn00 + 6 C00.2~ + 2 NH_ '+ 4 H00
1/42 4 2 243 2
(C12H4N2)2+ + 23 C10~ " 23 C1~ + 6 C2°42~ + 2 NH3 + 9 H2°
Although Faust and Gomaa did not determine stoichiometry for chlorine dioxide
(CIO ), it can be estimated from the expected Cl(IV) valence that complete
oxidation will require less than 12:1 ratio of CIO to paraquat. However,
CIO is too hazardous for use.except by skilled technicians (lOla). Complete
oxidation with the other reagents will require massive volumes of decontaminant.
If chlorine bleach (5% as HOCl) is used, it is estimated that paraquat (1.29
moles/£) will require a minimum of 42 volumes of bleach (ca 0.7 moles/?- as
HOCl). If 80:1 (vol/vol) of bleach is used, the calculated 99.9% degradation
time, t g, is calculated as 438 days at pH 10.13. For 0.5 molar KMnO
(the approximate solubility limit) the oxidation will require a minimum of
36:1 ratio of oxidant to paraquat. For 70:1 (vol/vol) of 0.5 molar KMnO :
paraquat, t is about 6.5 hours.
121
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Ln conclusion, no chemical method is recommended for paraquat detoxifica-
I. ion. I nsuff i c ionL information is avaiLahk1. to evaluate: t lie product toxicJty
from il.s chemical hydrolysis. CheinicaJ oxidalion requires very excessive
voJumes of de.toxicant. Reaction time with aqueous chlorine is too slow.
The non-chemical disposal procedures recommended by EPA are recommended for
paraquat disposal (7a). Its containers should be rinsed by the NACA recom-
mended procedure (Section 3).
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B.16 CHEMICAL METHODS FOR DKTOX1 1' f.CATION OK 1JENTACHI,OKON I TROBENZENIi (PCNB)
PCNB (Terrachlor) 'is applied as a soil fungicide and seed treatment. It
has a very low solubility in water (0.44 ppm at 20°C), is slightly solubie in
alcohol (2% at 25°C), and is soluble in ketones and aromatic and chlorinated
hydrocarbons. It is formulated as a 24% emulsifiable concentrate (2 Ib/gal),
dust (6.25, 10, 20, 40, and 75% wettable powder). PCNB is very stable in soil
(15, 103, 104).
Strong alkali hydrolyzes PCNB to pentachlorophenol (PCP) and nitrite (28):
C,C1CNO_ + OH~ - >- C.H.OH + NO ~
o _> i o j /
PCP,. which is also a pesticide, was reviewed by Shih and Dal Porto (1). PCP is
more toxic than PCNB; comparative ora.l tox ic i.t ies (LD ) for rats are 1650 and
27 mg/kg (4). Since PCP should be disposed by land burial, the hydrolysis is
not a useful detoxification method.
PCNB is reduced to the amine by stannous chloride and sulfuric acid (104):
No data was found on the toxicity of pentachloroaniline. Since many anilines
are carcinogenic (67) , it is concluded that pentachloroaniline is possibly
carcinogenic .
PCNB and empty containers should be disposed by an EPA recommended proce-
dure (7a). Bottles and drums should be triple rinsed with water and the rinse
water used for a diluent if possible.
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B.17 CHEMICAL METHODS FOR DETOXIFICATION OF DNBP (DINITRO-s-BUTYLPHENOL)
DNBP (Dinoseb) is applied as a pre- and post-emergence herbicide for
weeds and grasses, as a desiccant for field crops, as a topical weed control,
and for blossom thinning in fruit trees. DBNP is a nitrophenol. While the
Tree acid i.s relatively water insoluble (0.005 g/lOOg), it forms water soluble
salts. Dinoseb is soluble in ethanol (48 g/lOOg) and miscible with toluene
and ether. It is corrosive to common metals (15, 18).
DNBP is formulated as the free acid in a 5 Ib/gal emulsifiable concen-
trate and as alkanolamine salt (3 Ib/gal as dinoseb). Several dinoseb esters
are also marketed which include carbonic acid diesters, the acetate ester, and
the methacrylate ester. Also, dinoseb analogs contain other alkyl groups
substituted for the sec-butyl at the ortho position; these include dinocap
(£€!c-octyl) and dinex (cyclohexyl) (14, 28). DNBP reacts with alkylating
agents, oxidizing agents and reducing agents. Diazomethane reacts with it to
yield the methyl ether (105). Acyl chlorides convert dinoseb to esters (28).
The s-butyl group is oxidized to the benzoic acid with permanganate or chromate,
but the product's toxicity is not known. Very strong oxidants can oxidize the
nitro groups to produce quinones. Reducing agents convert nitro groups to
amines (106). None of these reactions are practical disposal operations, in
part, because they require some advanced technical skills.
Although environmental degradation is not well known, DNBP appears
resistant to biodegradation (106). The free acid is the preferred state if
DNBP is land disposed, since salts such as the alkanolamine are expected to be
transported more rapidly with moving ground water.
DNBP and its empty containers should be disposed by an EPA recommended
procedure (7a). Empty bottles and drums should be triple rinsed by the NACA
recommended method (Section 3).
124
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B.18 CHEMICAL METHODS FOR DETOXIFICATION OF CHLOROPICRIN
Chloropicrin is a stored grain and soil fumigant. As a soil fumigant it
is applied for pre-planting control of insects, nematodes, fungi, and weed
seeds. Chloropicrin is soluble in water at 2.27 g/£ at 0°C, and is miscible
with acetone, methanol, carbon tetrachloride, and benzene. Chloropicrin boils
at 112°C (233.6°F). The liquid is available in glass bottles (15, 107). It is
also formulated with methyl bromide and chlorinated C hydrocarbons (16).
Brozone: CH Br 68.6%; CC1 N02 1.4%
Dowfume MC-2: CH Br 98%; CC13N02 2%
Dowfume MC-33: CH Br 67%; CC1 NO. 33%
J -J £
Telone C: CC13N02 15%
Chloropicrin is relatively stable toward hydrolysis in water, dilute acid
and dilute base. But, it does react with some very strong acid and base systems.
Fuming sulfuric acid at 100°C reacts with Chloropicrin to yield phosgene and
nitrosyl chloride (108), which are more toxic than Chloropicrin (4). Sodium or
potassium methylate hydrolyze Chloropicrin to non-toxic products (107):
3NaCl
But, preparing methylate (adding metallic sodium or potassium to ethanol) and
reacting methylate with Chloropicrin are dangerous reactions (38).
Iodide, either as hydriodic acid or alkali iodide, degrades Chloropicrin (108)
The hydriodic acid reaction yields ammonia, carbon dioxide, chloride ion and
iodine. Iodide.salts will yield carbon tetraiodide. Neither reaction is
judged suitable. Hydriodic acid is a hazardous reagent (38). Carbon tetra-
iodide, like carbon tetrachloride, might be carcinogenic (4).
125
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Hot alcoholic sodium peroxide oxidizes chloropicrin. Products are sodium
carbonate, nitrate, and chloride ion (109).
When chloropicrin is heated at 100°C with ammonia for several hours, it
yields guanidine (108). Since guanidine is non-toxic., the .method has been
recommended for detoxification (3). However, several of the alternatives are
judged more practical. A good alternative consists of heating chloropicrin
with potassium acetate and alcohol at 100°C; products are potassium carbonate,
ethyl acetate, and chloride ion (108). All products are non-toxic (4).
Chloropicrin reacts quite smoothly with sulfides and trisubstituted phos-
phines at ambient temperatures (28, 108). Although reaction with free mer-
captans is slow, reaction is rapid with alkali mercaptides. Products with
mercaptides are the corresponding disulfide and a mixture of carbon dioxide and
nitrogen (major) and carbon monoxide and nitrous oxide (minor). Although the
minor products (CO and NO) are slightly toxic, they are less toxic than chloro-
picrin (4). The reaction between chloropicrin and trisubstituted phosphines
yield parallel products: the corresponding phosphonic dichlorides and a mixture
of carbon dioxide and nitrogen or carbon monoxide and nitrous oxide. The
method is not judged practical since the reagents (mercaptans or trisubstituted
phosphines) are noxious and require some skills for handling (38).
Chloropicrin is reduced by iron filings to yield methylamine and chloride
ion (110);. The reaction requires an aqueous acid media to reach completion.
Some technical skill is required to maintain proper temperature, since the
reaction is quite exothermic. The recommended procedure is to slowly add the
chloropicrin to a cooled mixture of fine iron filings in aqueous acid.
126
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Chloropicrin is photoreactive (108). An intereating reaction occurs when
clijorop Lcr in solution (methnnol, etlianoi, acetic acJd, benzene) is It-It in
Sunlight. After one day of exposure lite chiorop Icr i n is reduced to ammonia
and unknown organics. The reaction does not take place in the dark.
Chloropicrin is not inflammable (111). While it could be incinerated,
this would require the addition of fuel. Recommended conditions are a primary
combustion at 1,500°F for 0.5 seconds minimum and secondary combustion at
2,200°F for 1.0 second minimum. The incineration products are very corrosive
and must be scrubbed (111).
Chloropicrin should be disposed by an alternative, EPA recommended pro-
cedure (7a). Bottles should be thoroughly drained and triple rinsed by the
NACA recommended procedure (Section 3).
127
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128
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APPENDIX C.
CHEMICAL METHODS FOR THE DETOXIFICATION OF
HALOGEN-CONTAINING PESTICIDES
C.I GENERAL REVIEW OF APPLICABLE DISPOSAL METHODS
The halogenated hydrocarbon pesticides encompass a wide range of chemical
structures (Table 30). Their hazards are often, but not always, associated
with the halogen content. Since dehalogenation is the usual detoxification
approach (1, 2), a general review of this subject is presented in this section.
Pesticides which can be detoxified by other approaches will be discussed on a
case-by-case basis.
Dehalogenation can be achieved by a variety of ionic and reductive processes.
The ionic reactions discussed herein are characterized as nucleophilic (48).
The most useful nucleophilic reagent is hydroxide, which reacts fairly readily
with aliphatic halogen to yield substitution and elimination products.
substitution , + x-
-C-C- + OH ' H °H
11 \ \ ,-
H X \ elimination C=C + X + H00
> ^ \ 2
Stronger electrophiles such as the alkoxides (methoxide, ethoxide) and amide
react with aliphatic halides in the same way to produce analogous products.
They also react with olefin and aromatic halogen:
substitution ^ ' -
elimination -C=C- + X f HY
129
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Table 30. Chemical Structures of Selected Halogen-
Containing Pesticides.
NAMK
STKUCTIJKK
MW
DDT Relatives
Chlorobenzilate
325.2
Chlorophenoxy derivatives
Cl
cl
0
H
OCR COR
Cl
255.5 (R=H)
Aldrin-Toxaphene group
Endrin
0
380.9
Aliphatic brominated hydro-
carbons Dibromochloro-
propane (DBCP)
BrCH-CHBrCH Cl
236
Aliphatic and Alicyclic Chlorinated Hydrocarbons
Benzene hexachloride (BHC)
C,H,C1,
DO D
290.8
D-D
Mixed dichloropropanes
& dichloropropenes
Highly Chlorinated Aromatics
Dicamba
Cl
OCH.
Cl
221.0
130
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Potentially useful nucleopliillc renpeiits lor pesticide detoxification Include
alkali amides, sodium biplicnyl, and alkali alkoxides (methoxide, ethoxido,
etc.) (3, 113, 114). Strong acids participate in electrophilic reactions by
assisting in ionization of halide and by catalyzing rearrangement reactions
(48).
Catalytic hydrogenation will dehalogenate practically any chlorinated
hydrocarbon; however, dehalogenation requires highly sophisticated equipment,
expensive catalytic reagents, and well trained technicians. Catalytic hydro-
genation requires heating the pesticide within a hydrogen atmosphere in the
presence of a transition metal catalyst (3, 48). Since it is not practical,
proposals to use it for the selected pesticides will not be discussed further.
Halogenated hydrocarbons can be degraded by a variety of reducing agents.
Alkyl halides are reduced by hydride transfer agents, such as lithium aluminum
hydride and with reactive metals and metal complexes, such as magnesium or
chromous chloride (48). Vicinal dihalides will reductively dehalogenate to
yield olefins with metals (sodium, zinc, etc.), metal hydrides (e.g., LiAlH ),
and other reducing agents (e.g., iodide) (48, 115).
II \ s
-C-C- + M >• C=C + MX,
Y 5 ^ \ t
A A
Although dechlorination could be achieved with almost all the halogenated
pesticides, it is not practical as a general approach. Most of the reagents
are expensive and too hazardous for general use. Stronger caustics than 10 to
20% sodium hydroxide are considered too hazardous for general use. Many of the
reagents used for reductive dechlorinations are pyroforic, for example, sodium
metal (38).
131
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C.2 CHEMICAL METHODS FOR DETOXIFICATION OF CIILOROBENZJ LATE
Cli I orobc-nx. il;i i;e Is an .-ic:ar;ic: I do u.st'il for a variety ol' agr I <;u I I ura I crops
.•UK! on ornamentals. The inosL common formulae ions are cunulsi f iah.l «.: concent raLc-s .
Other formulations include a 25% wettable powder, and 3% dust. Chlorobenzilate
is practically insoluble in water, but soluble in alcohol, acetone, and xylene
(15, 23).
Chlorobenzilate can be hydrolyzed by strong acid or alkali (2). The
initial product from alkaline hydrolysis is sodium Chlorobenzilate. If this
sodium salt is neutralized or if Chlorobenzilate is hydrolyzed in acid media,
the intermediate chlorobenzilic acid rapidly decarboxylates to yield £,£*-
dichlorobenzophenone.
OH
I
C - CO + C H OH
C-COC2H
.OH
Chlorobenzilate has a relatively low acute hazard (oral LD = 700 mg/kg
for rats), but, it has yielded a positive test as a carcinogen (4). The only
toxicity information found for £,£* -dichlorobenzophenone is its reported inter-
peronital LD5Q of 200 mg/kg (for rats). It is not clearly certain that this
method does represent a significant detoxification of Chlorobenzilate. Its
advantage is that no evidence would suggest that dichlorobenzophenone is
carcinogenic. But, it does not seem to substantially reduce acute hazard.
132
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No evidence was found concerning the environmental fate of dichlorobenzo-
phenone. Based on the evidence at hand, the chronic exposure hazard from
chlorobenzilate is judged minimal, so, hydrolysis is not recommended.
Chlorobenzilate can be dechlorinated by sodium in isopropyl alcohol. The
organic products have not been identified (23).
Chlorobenzilate should be disposed by the EPA recommended procedures as
an alternative to chemical detoxification (7a). Empty bottles and drums
should be thoroughly drained and rinsed by the NACA recommended method
(Section 3).
133
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C.3 CHEMICAL METHODS FOR DETOXIFICATION OF 2,4,5-T
2,4,5-T (2 ,4,5-lr ichl.orophenoxyacetic. acid) Is a selective herbicide,
wlifch is used primarily for brush and broadleaf weed control (1.5, 45). The
free acid has only a slight water solubility (278 ppm) and is soluble in
acetone and ethanol. Most 2,4,5-T is formulated as derivatives of the free
acid. Aqueous formulations contain the water soluble salts of amines or alkanol-
amines and formulations in petroleum oil are prepared from esters (15). 2,4,5-
T contains trace quantities of a highly toxic teratogen, 2,3,7,8-tetrachloro-p-
dioxin (TCDD). The technical material is contaminated by less than 0.5 ppm of
TCDD, while its threshold toxicity appears about 30 ppm (91).
Cl
Cl
2,3,7,8-tetrachloro-£-dioxin (TCDD)
The chemical and physical properties of 2,4,5-T are analogous to 2,4-D
(1, 91). 2,4,5-T is cleaved by strong acid to 2,4,5-trichlorophenol, formalde-
hyde, and carbon dioxide; glycollic acid appears to be an intermediate (91).
Cl
H
OCH2C02H
OH + HOCH2C02H
CH20 + CO + HO
This hydrolysis requires heating with concentrated acid or pyridine hydrochloride,
2,4,5-T is completely degraded by alkali metals (Na or Li) in liquid ammonia, but
134
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the degradation products have not been identified. Chlorination is capable of
destroying 2,4,5-T. Aqueous hypochlor 1 tc at pll '5 and temperatures above 85°I'
will yield herbicidally inactive products, but the products have not been
characterized (113, 114). At high temperature (about 400°C) chlorinolysis can
degrade 2,4,5-T to a mixture of carbon tetrachloride, phosgene, and hydrogen
chloride (116). None of these reactions are practical detoxification approaches
for 2,4,5-T.
Chemical treatment is not considered a viable approach for degrading the
trace quantities of TCDD. Cleavage of the ether and dechlorination requires
highly reactive chemical reagents, such as strong acid or sodium amide (48)-.
Both 2,4,5-T and TCDD are degraded by photochemical reactions (91, 117).
TCDD will degrade to non-toxic products in sunlight provided an organic
hydrogen donor is available. This photochemical reactivity has been proposed
for TCDD and other chlorinated dioxin spills (118). The degradation will be
completed in a matter of days, if sufficient sunlight is available.
2,4,5-T is detoxified by microbial activity in a period of 45 to 270 days
(91). The biodegradation is most rapid in warm, aerated, moist soils, and
aerobic activity is preferred. TCDD is relatively persistent in soil. Kearney
and coworkers report that approximately 60% was recovered after 1-100 ppm TCDD
was incubated for one year in loamy sand or silty clay loam (117). It would
appear that TCDD could build up in soil if 2,4,5-T containing trace amounts of
TCDD were disposed by land burial.
In summary, no practical chemical detoxification procedures are now avail-
able for waste 2,4,5-T. The photochemical degradation to remove traces of TCDD
is an interesting approach for spill clean-up but not for disposal. The
135
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photochemical method could conceivably result in vaporization of the volatile
2,4,5-T esters. So, it was only suggested as a possible detoxification approach
for accidental spillage.
Shih and Dal Porto have recommended that free acid and salts of 2,4-D
should be precipitated from liquid formulations with calcium or magnesium
salts to reduce transport with groundwater (1). This method would also
mitigate migration if 2,4,5-T were disposed by land burial.
The EPA recommended procedures should be used as an alternative to
chemical detoxification for disposal of 2,4,5-T and its containers (Section 3)
(7a).
136
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C.4 CHEMICAL METHODS FOR DETOXIFTCATlON OF ENDRTN
Endrin is an insecticide for cotton pests and other field crops. IL has
also been applied for mouse control. Endrin is almost insoluble in water and
is sparingly soluble in alcohols. It is formulated in wettable powders (25%
and 50%), dusts and granules and a 1.6 Ib/gal emulsifiable concentrate (15,
23).
Endrin is a chlorinated dicyclopentadienyl pesticide which has analogous
chemical reactivity to other members of this class, such as aldrin and dieldrin.
It is not reactive with alkali or weak acids. Endrin has a double bond which
undergoes typical olefinic reactions, such as halogenation and oxidation. But,
reaction products have not been well characterized. Endrin (I) undergoes
skeletal rearrangements and dechlorinations as the result of thermal treatment,
ultraviolet irradiation, reactions with Lewis and Bronsted acids (including
boron trifluoride and sulfuric acid) and chemical reduction (119, 120).
Mixtures of less toxic products are formed by thermal treatment (200°C or higher),
mild heating (less than 100°C) with acids (including BF , ZnCl plus HC1,
H SO , and HC10 ) or ultraviolet irradiation (119, 121-123). The products are
ketone II, aldehyde III, and alcohol IV. Oral toxicities (rats) are reported
at 62.1 and 500 mg/kg for II and III, respectively (120, 121). No toxicity
information was found for IV. In comparison, oral LD for endrin is 3 mg/kg.
OH-o
II
III
IV
137
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KiKlrJn I.H rt'dnc. i I voly dechlorLnated. Sodium methoxide in dimethyj sulf-
oxiclr dcchlorlna tiis llii1. antI-posit Ion of the l>rJdge di.chloromethario-group
without skeletal rearrangement (119). Metallic reducing agents initially
convert endrin to A-keto endrin, structure II, before reducing the anti-
chloride to yield ketone V. Reducing agents yielding V include zinc plus acid
or chromous chloride (119). Sweeny and Fisher reduced endrin with zinc dust
and zinc-copper couple in an acetic acid-acetone mixture for 21 to 22 hours
(125). About 10% of the initial endrin remained and only 25% of the theoretical
chlorine was identified as soluble chloride.
Ultraviolet irradiation also can reduce endrin. Its irradiation in hexane
solution yielded a product with hydrogen replacing one of the bridgehead
chlorides. Perumal has evaluated products from irradiation of the chlorinated
dicyclopentadienyl derivatives and obtained products with reduction of anti-
position of the dichloromethano-bridge analogous to structure V (126).
Although endrin is chemically converted to products of lower acute toxicity,
none of the methods are suitable for recommendation at this time. The reagents
and conditions required are judged too advanced for general recommendations.
The addition of metals or their salts, such as zinc or iron, show promise, but
more information is required. Also, chronic effects of the rearranged products
should be examined.
-------
The EPA recommended procedures should be used for disposal of endrin and
its containers (7a). Empty bottles and drums should be triple-rinsed by the
NACA recommended method (Section 3).
139
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C.5 CHEMICAL METHODS FOR DETOXIFICATION OF DIBROMOCHLOROPROPANE
D1bromochloropropane (DBCP) Is a soil fumigant used for nematode control.
11 is formulated as emulsiftable and non-emulsifiable concentrates, and granules.
The most popular formulation contains 12.1 pounds active ingredient per gallon
(14, 15). DBCP has a water solubility of 1 g/kg at ambient temperature and is
miscible with alcohols and acetone. It boils at 196°C (15).
DBCP is stable in dilute acid and neutral solutions, but Is hydrolyzed in
alkaline solution. The products depend upon the hydrolysis conditions. It is
easily hydrolyzed to 2-bromoallyl alcohol in aqueous base (104, 127).
BrCH2CHBrCH2Cl — >• CH2 °H
But, since the product, 2-bromoallyl alcohol, is a vinyl halide, it could be
carcinogenic (67). With more vigorous conditions, the vinylic bromide is
further degraded to acetylenic derivatives. Reflux with aqueous caustic will
yield propargyl alcohol (125, 127).
H2C=CBrCH2OH — *» CH«CCH2OH + H20 + Br"
The toxicity of propargyl alcohol is very high; oral LD for rats is listed
as 70 pg/kg (4). DBCP hydrolysis in potassium ethoxide (prepared by adding
potassium metal to ethanol) yields ethyl propargyl ether (127).
KOC^H
BrCH CHBrCH Cl — » HG-CCH OC.H.
C H OH ^ Z *
140
-------
Although no toxicological data was found for this ether, the relatively Jow
toxicity (oral LD of 539 mg/kg for rats) of dipropargyl ether, (CM CCII ) (),
suggests that ethyl propargyl ether will have a low toxicity. Kennedy and
coworkers achieved 100% DBCP degradation with sodium or lithium metal in
liquid ammonia-hexane (114). The products were not characterized. Rauscher
reports that aliphatic halides are extensively dehalogenated by sodium ethan-
olamine in dioxane, but organic products were not identified (128). Rauscher
prepared the reagent by adding metallic sodium to a monoethanolamine-dioxane
mixture.
DBCP can be dehalogenated by metallic reducing agents. Kray and Castro
have reduced DBCP to propylene with chromous chloride in 2:1 water-dimethyl-
fonnamide (DMF) (129, 130). The conversion proceeds in two steps. DBCP
rapidly reductively debrominates to yield allyl chloride which is subsequently
2Cr + + CH2BrCHBrCH2Cl - y CH2=CHCH2C1 + 2CrBr2+
Cr + CH2=CHCH2C1 * CH2=CHCH3 + CrCl2+
reduced to propene. They measured kinetics for the allyl chloride reduction
at 29.7°C. The rate was second order:
Rate - k2 [Cr2+J[c3H5c£!
with k2 = 1.2+0.1 i/mole-min.
Zinc-acid mixtures could be an effective reagent for DBCP dehalogenation.
Zinc with either acetic or hydrochloric acid is a commonly used reducing uy,rii(.
141
-------
for dehalogenation (48, 131). This reagent is well known for debromiriatirig
vicinal bromides and is capable also of removing halide from vinylic carbon.
Although zinc-acid reagents have been used for extensive dehalogenation of
pesticides, no information on its use for DBCP was found (125, 132).
None of the current methods are acceptable for DBCP detoxification. All
require hazardous reagents and fairly sophisticated techniques. The EPA
recommended procedures should be used for disposal of DBCP and its containers
(7a). Containers should be triple-rinsed by the NACA recommended procedure
(Section 3). The manufacture recommends that DBCP should be incinerated, if
possible (133). Its incineration requires dilution with inflammable solvent
and facilities to scrub the HC1 and HBr evolved.
142
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C.6 CHEMICAL METHODS FOR DETOXIFICATION OF BHC
BHC is also known by several alternative names: benzene hexachloride,
HCH, and hexachlorocyclohexane. BHC is a mixture of stereoisomers of 1,2,3,4,5,6-
hexachlorocyclohexane and a trace amount of related chlorinated cyclohexanes.
The most important constituent is the Y-BHC isomer, lindane. Currently, BHC
is being phased out as a pesticide, but purified lindane is remaining. Lindane
is the dominant isomer which influences BHC insecticidal activity. BHC (and
lindane) are formulated in numerous products, both as the sole active ingre-
dient and combined with other active ingredients. The formulations include
emulsifiable concentrates, dusts, granules, and oil solubles. Percentages
generally range from 0.1 to 20%. Applications include seed treatment, animal
pest control, and forestry (14, 141).
Table 31 describes the major constituents of BHC. BHC is also formulated
with increased lindane content. A complete description of chemical behavior
and physical properties would require evaluation of each isomer. Since this
is beyond the scope of this report, a general review of gross behavior of the
mixture and only salient properties of the individual isomers is presented
herein. The mixture behaves as expected for chlorinated hydrocarbons. Reac-
tivity differences arise primarily from stereochemical constraints within the
cyclohexane structure. For a detailed discussion one of several reviews
should be consulted (119, 135).
-4 -4
Isomers range in solubility: 0.5x10 to 1x10 g/lOOg in water; 1.1 to
24.2 g/lOOg in ethanol; 1.1 to 41.1 g in benzene; and 7.9 to 71.1 g/lOOg in
acetone (28).
BHC is relatively stable to chemical oxidation. It does not react with
chlorine, peroxide (^2°2 or Na2°2^» and Permanganate, but is degraded by ozone
143
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Table 31. Description of BHC Composition.
Adapted from Melnikov (28) and
Cunt lie r and IU Inn (.152).
ISOMER
STRUCTURE
PERCENTAGE
65-70
6-8
Y
Cl
H
H
H
CJ
a
ci
Cl H
12--15
Cl
H
Cl
2-5
and other
chlorinated
cyclohexanes
Cl Cl
Cl
H
Cl
H
Cl
Cl
3-7
144
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to unspecified products (150, 151). It can be catalytically dehydrogenated to
yield hexachlorobenzene (28, 135).
Reducing agents dechlorinate BHC and yield benzene. The zinc-acetic acid
system is a well known reagent for this reduction (132. 135). The zinc-acetic
acid reduction is not recommended as a general detoxification method. The
product, benzene, has a relatively low toxicity (oral LD of 756 mg/kg for
rats), but it is a suspected carcinogen (4). Also, the alkyl halide dechlorin-
ation reaction with zinc and acetic acid generates heat and frothing when it
is performed as bulk reaction (137).
BHC is stable toward hydrolysis in neutral and acid media. BHC does
hydrolyze very slowly at room temperature; only 0.13% of the HC1 is lost by
the y-isomer after heating at 102° for 1 hour (28). Although BHC is generally
inert to aqueous acids, some reactions occur with very powerful acids. Chloro-
sulfonic acid can degrade it to benzene and other products (119). Also, Lewis
acids, such as aluminum chloride, catalyze the isomerization bet'ween the BHC
isomers to yield new compositions (28).
Alkaline media (and nucleophilic reagents such as amines) will hydrolyze
all BHC isomers except the 3-isomer (138, 139). The stability of the 6-
isomer results from stereochemical relationship of the chloride atoms. The
products are trichlorobenzene isomers. Yields ranged from 60 to 80%, 4 to
10%, and 6 to 15% for 1,2,4-, 1,3,5- and 1,2,3-trichlorobenzene, respectively
(119).
The hydrolysis rates (with the exception of the 3-isomer) are amenable to
practical detoxification. Cristol has delineated the kinetics (139). Hydrol-
ysis is second order: first order both in BHC and hydroxide. Table 32
145
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summarizes apparent first order rate constants for the hydroxide reaction in
aqueous ethanol.
C,H,C1, + 30H ——+ C,H_C10 + 3H00 + 3Cl
ODD O J J /
Table 32. Apparent First-Order Rate Constants For Hydrolysis
Of BHC Isomers To Trichlorobenzene With Sodium
Hydroxide In 76.1% Ethanol At 20.11%.
Isomer k ,
obs
(£/mole-sec.)
a 0.167 - 0.172
B 3x10-°
Y 0.0435 - 0.0457
6 0.106 - 0.113
Time for 99.9%, t , BHC degradation (with the exception of the 3-isomer)
can be calculated from Equation A-7 with n = 3. Approximate t n QQ was cal-
u • y y y
culated for BHC hydrolyzed with IN hydroxide in 50% aqueous ethanol. t n
was calculated for 1 pound of BHC mixed with 3.7 £ (1 gal) of detoxicant and an
estimated rate constant of 0.044 £/mole-sec (k , for the y-isomer). These
obs
parameters yield t . of approximately 3.5 minutes. The trichlorobenzenes
have an advantage with respect to known toxicities. The acute oral LD of
1,2,4-trichlorobenzene is 756 mg/kg for rats. In comparison, y-BHC has an oral
LD50 °f 88 m8/k8 for rats. Also, BHC has yielded positive tests for carcino-
genesis, while the chlorobenzenes are not known to produce any long-term
-------
exposure effects (4, 67). Disadvantages of alkaline hydrolysis include its
inability to degrade the 3-isomer.
Except for the 8-isomer, BHC appears to metabolize in the environment
(140, 141). B-BHC which is persistent accounts for about 7% of technical BHC.
BHC metabolites which have been identified include chlorinated phenols, chlor-
inated benzenes and has chlorinated cyclohexanes. The trichlorobenzenes are
environmentally persistent and capable of bioaccumulating (142-145).
In conclusion, alkaline hydrolysis does offer a moderate reduction in
acute toxicity. Although the hydrolysis products are not at this time, sus-
pected carcinogens, they apparently bioaccumulate. Because the hydrolysis
products are a potential hazard, the method is not recommended. Instead, an
alternative, non-chemical method in accordance with the EPA recommendations
should be used for disposal (7a). Empty bottles and drums should be tripe-
rinsed by the NACA recommended method (Section 3).
147
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C.7 CHEMICAL METHODS FOR DETOXIFICATION OF D-D
D-D is a soil fumigant which consists of a mixture of chlorinated C
hydrocarbons; it is primarily used as a pre-plant nematocide. D-D composition
is (28):
cis-1,3-dichloropropene 30-33%
trans-1,3-dichloropropene 30-33%
1,2-dichloropropane 30-35%
Trichloropropanes plus more up to 5%
highly chlorinated products
D-D distills in the range 95-150°C. It is soluble in water at 2 g/i (104).
Chemical reactivity corresponds to expected behavior for chlorinated
aliphatic hydrocarbons, but information is not well developed. The manufac-
turer reports that it reacts with dilute inorganic bases, concentrated acid,
metal salts, and active metals, but does not describe the products (2, 146).
Product information can be derived from known chemistry of the major components.
The major components are the cis and trans isomers of 1,3-dichlorppropene.
These allylic chlorides are easily hydrolyzed with hydroxide to yield 1-
chloropropen-3-ol (127). a-Chloroallylic alcohol will eliminate HC1 when
treated with base in vigorous conditions. The product is propargyl alcohol,
CH=CCH OH, which has a high oral toxicity (See Section C.4). The dichloro-
propenes will react with potassium ethoxide or potassium acetate, to yield the
corresponding ether (C2H5OCH2CH=CHC1) and ester (CH C02CH2CH=CHC1), respectively.
Dichloropropene is not reactive with fuming sulfuric acid at 100° to 150°
(127).
1,3-dichloropropane is not as reactive as the dichloropropenes (48, 127).
It is relatively stable with sodium amalgam or zinc plus acetic acid. Jt reacts
with potassium ethoxide to yield 1-chloropropene. It will hydrolyze with
148
-------
water at 210° to 220°C or at 150°C if heated with PbO and water. The initial
product, propanediol will rearrange to yield acetone and propionaldehyde.
Since no suitable method of chemical detoxification is available the EPA
recommended procedures should be followed for disposal of D-D and it is con-
tainers (7a) (Section 3).
149
-------
C.8 CHEMICAL METHODS FOR DETOXIFICATION OF DICAMBA
Dicamba (Banvel) is a post-emergence herbicide. It is used as the free
;icltJ or Its salts, usually the dimethylamine salt. The free acid has water
solubility of 4.5 g/& at 25°C, is soluble in ethanol and acetone, and moder-
ately soluble in xylene. The dimethylamine salt has a water solubility of 720
g/£. Dicamba is marketed in several formulations including 4 Ib/gal water
soluble, 4 Ib/gal oil soluble, and 5 and 10% granules. Also, it is combined
with other herbicides in numerous formulations (14, 15).
Dicamba is chemically relatively inert (2). It is stable to oxidation
and hydrolysis. The carboxylic acid can be derivatized, but the procedures
would only be useful for analytical purposes (148). Kennedy and coworkers
found that sodium or lithium with liquid ammonia in hexane will dehalcgenate
dicamba; products were not reported (113). Dicamba appears photochemically
stable (149).
The EPA recommended procedures should be used for disposal of dicamba and
its containers (7a) (Section 3). The manufacturer recommends disposal by land
burial or incineration (150). If dicamba is land disposed, its conversion to
the acid form could reduce its mobility in soil.
150
-------
APPENDIX D
CHEMICAL METHODS FOR THE DETOXIFICATION OF
INORGANIC AND METALLO-ORGANIC PESTICIDES
D.I GENERAL REVIEW OF APPLICABLE DISPOSAL METHODS
The two pesticides selected, arsenic acid and MSMA (monosodium methane-
arsonate), characterize the inorganic and organometallic arsenicals, respectively.
Disposal problems of the arsenicals reflect problems experienced with other
metal and metalloid pesticides (2). The element, arsenic, is ubiquitous in the
environment and exists in a wide variety of inorganic and organic compounds
(151). Its environmental behavior parallels that of mercury (152).
Although arsenic will remain a toxic metal, its hazard can be mitigated.
Highly toxic arsenic compounds can be degraded to compounds of lower toxicity.
Leaching problems can be reduced by preparing precipitates which are either
fixed or slowly release the arsenic. The reactions most important for disposal
are oxidation-reduction and ion exchange.
151
-------
n.2 CHEMICAL METHODS FOR DETOXIFICATION OF ARSENIC ACID
Arsenic acid which Ls applied as a cotton desicant and herbicide is
marketed as a 75% (by weight) liquid concentrate (14, 153). Its solubility is
16.7 g/100 ml in cold water and 50 g/100 ml in hot water (154).
Arsenic acid is weakly amphoteric. Heavy metals will react with it to
yield insoluble.precipitates, some of which are used for quantitative analysis
of As(V) oxides. Metals which quantitatively precipitate arsenic acid include
magnesium, lead, calcium, and iron (III) (155, 156). Arsenate precipitation
with ferric hydroxide has been suggested to reduce its phytoxicity (151). Its
precipitation will also reduce its potential for leaching. Arsenate could be
suitably precipitated with a slight excess of lime, ferric hydroxide, or
magnesia. The best procedure is to stir ferric chloride, or a hydrexide of
ferric, calcium, or magnesium into the waste arsenic acid and allow the.mix-
ture to stand 24 hours. Then, the supernatant water should be siphoned or
decanted, (2).
An alternative procedure would be to precipitate arsenic with sulfide.
Since the method requires more sophisticated handling, the precipitation with
heavy metals is preferred. The sulfide precipitation requires decreasing the
solution acidity to less than pH 1 with 6N HC1, then saturating the solution
with sodium sulfide or hydrogen sulfide (155). The precipitate and super-
natant should be handled just as described for the ferric or other metal
arsenate.precipitates.
The EPA recommended procedures should be used for disposal of arsenic
acid and its containers (7a). Empty containers should be triple-rinsed by
the NACA recommended procedures (Section 3). Although the precipitation of
152
-------
arsenic acid could reduce its mobility in the environment and its toxicity,
insufficient environmental testing is available to verify this conclusion.
The precipitates should be considered hazardous. Any use of precipitation
should only be in strict accordance with the EPA recommended procedures (7a)
153
-------
.iiL METHODS FOR DETOXIFICATION OF MSMA (Monosodium Methanearsonate)
MSMA is a selective post-emergence contact herbicide. It is soluble in
water (570 g/£ at 25°C) and in methanol. MSMA is formulated as 6 and 8 Ibs/gal
liquids (14, 15).
MSMA is a member of a group of methylated arsenic acid analogs. It is the
monosodium salt of methanearsonic acid,
0
II
HO-As-OH
1
OH
senic Acid
0
I!
CH--AS-OH
J 1
OH
Methanearsonic
Acid
0
M
CH0-As-CH,
3 | 3
OH
Cacodylic
Acid
which is in equilibrium with the free acid and the disodium salt, DMSA (151).
? PK -3.61 ° PK =8.24 °
CH -As-OH -»• CH--As-ONa — a *> CH -As-ONa
J i *= J i «=j i
OH OH ONa
Arsenic Acid MSMA DSMA
The methyl group of methanearsonic acid is stable to hydrolysis. It can
be oxidized by heating it at 315°C in sulfuric acid or at lower temperatures in
nitric acid-sulfuric acid mixtures (157-159). Methanearsonic acid can also be
reduced to yield derivatives of trivalent arsenic. Its reaction with S0~ in an
aqueous halogen acid (HC1 or HBr) yields the corresponding methylarsine dihalide
(CH_AsX_). When it is reacted with a sodium sulfite-hypophosphorous acid mix-
ture, it forms a polymeric sulfide, [CH0AsS] . Methanearsonic acid reacts with
J n
H2S to yield the pentavalent arsenic disulfide, CH3AsS2 (158, 159).
Methanearsonic acid quantititively precipitates with a wide variety of
alkaline earth and transition metals. The metal salts exhibit amphoteric
-------
behavior; precipitation is pH dependent. For example, the quantitative preci-
pitation occurs at pH 3 for Al(III), at pH 4 for Cu(H), pH 5 for Mn(Il) or
Fe(II), at pH 6 for Zn(II), at pH 7 for Fe(III), and at pH 8 for Mg(II) (158,
159).
The EPA recommended procedures should be used for disposal of MSMA and its
containers (7a). Empty containers should be triple-rinsed by the NACA recom-
mended procedures (Section 3). The precipitation of MSMA might reduce hazard
if land burial is used for disposal. Since environmental fate of precipitated
MSMA is not known, if used, it should be considered potentially hazardous and
in accordance with the EPA recommended procedures (7a).
155
-------
156
-------
APPENDIX E
CHEMICAL METHODS FOR DETOXIFICATION OF MISCELLANEOUS PESTICIDES
E.I GENERAL REVIEW OF APPLICABLE DISPOSAL METHODS
Miscellaneous pesticides selected for study are sodium fluoroacetate
(Compound 1080), creosote, and warfarin. Their disposal will be discussed
individually.
157
-------
E.2 CHEMICAL METHODS FOR DETOXIFICATION OF SODIUM FLUOROACETATE
Sodium fluoroacetate (Compound 1080) is applied as a rodenticide and for
other mammalian predator control. Because fluoroacetate is extremely toxic,
its use is restricted to government, research or laboratory, or licensed pest
control operators (14). Sodium fluoroacetate is very water soluble and relar-
tively insoluble in organic solvents, including acetone and alcohol (161).
Relatively little information was available describing the chemical
reaction of fluoroacetate. The carboxylic acid group can be derivatized (to
yield esters and amides), which are about as toxic (162). The alkyl-fluoride
bond is chemically relatively stable (48). Methods for chemical hydrolysis of
the other alkyl halides either do not affect alkyl fluorides or hydrolyzes
them slowly. Aqueous fluoroacetate solution loses toxicity relatively slowly,
which indicates some hydrolysis (162). Powerful bases, such as sodium amide,
are capable of breaking the C-F bond in fluoroacetate. The C-F bond is also
relatively inert to oxidation (48).
Land burial is a dangerous disposal method even though fluoroacetate will
metabolize in the soil (161). David and Gardner evaluated the time required
until residues showed no toxicity when fluoroacetate was incubated in loam soil.
This required 2 and 11 weeks for 10 and 50 ppm fluoroacetate, respectively (164)
Higher fluoroacetate could conceivably result in longer periods. Another
hazard is that fluoroacetate can be translocated into plants or be transported
with ground water. When fluoroacetate is metabolized, it yields fluoride ion.
Fluoride is toxic, although far less toxic than fluoroacetate. For sodium
fluoride, oral toxicities are reported as LD of 4 to 75 rag/kg for humans and
158
-------
LD of 180 mg/kg for rats.(4). Fluoroacetate and its containers must be dis-
posed by a non-chemical alternative as described in the EPA recommended pro-
cedures (Section 3) (7a). The manufacturer will accept fluoroacetate for
reprocessing (163).
159
-------
E.3 CHEMICAL METHODS FOR THE DETOXIFICATION OF CREOSOTE
Creosote is a wood preservative derived from coal tar. The material is
\
prepared to conform to a specific distillation standard (American Wood Pre-
servers Specification Pl-65) (14, 165, 166). Creosote contains more than 200
separate constituents, most of which are polynuclear aromatic hydrocarbons (PAH).
Less than 20 constituents account for at least 75% of the creosote. Lorenz and
Gjovik have identified the major constituents and their approximate percentage
by gas chromatography; Table 33 summarizes their results (167).
Most of the constituents identified are PAH with three or more rings, less
than 10% are naphthalenes and biphenyl. Two constituents (carbazole and dibenzo-
furan) have heteroatoms (oxygen and nitrogen, respectively). The mixture is
high boiling (greater than 200°C) and has a very low water solubility (164).
PAH's are suspected carcinogenic agents (168, 169). One component, chrysene,
is a known carcinogen, while others including the largest single component
phenanthrene are suspected carcinogens. The PAH's are naturally produced and
ubiquitous in the environment. Evidence has been presented that they can
bioaccumulate. They can be biologically degraded, but the rate appears to be
slow (168, 169). Since it is beyond the scope of this study to detail reac-
tivity of all known constituents, general chemistry of the important consti-
tuents is reviewed.
Several groups have examined oxidation of PAH's by chlorine, chlorine
dioxide, and ozone (168, 170-172). These studies have been concerned with the
removal of PAH's from water in typical water treatment plants. The studies
have demonstrated that PAH's are oxidized and removed from water. Benzpyrene
yielded non-carcinogenic products with chlorinolysis; however, products were
160
-------
Table 33. Major Components in Creosote.
Adapted from Lorenz and Cjovlk (167)
Component Approx. Pet. ±0.7%
Naphthalene 3.0
2-Methylnaphthalene 1.2
1-Methylnaphthalene .9
Biphenyl .8
Dimethylnaphthalenes 2.0
Acenaphthene 9.0
Dibenzofuran 5.0
Fluorene 10.0
Methylfluorenes 3.0
Phenanthrene 21.0
Anthracene 2.0
Carbazole 2.0
Methylphenanthrenes 3.0
Methylanthracenes 4.0
Fluoranthene 10.0
Pyrene 8.5
Benzofluorenes 2.0
Chrysene 3.0
161
-------
not identified (168). Ozone also appears to oxidize PAH's, but products have
not been identified (168, 171, 172). Although hypochlorous acid reacts with
biphenyls (48), the chlorinated biphenyls produced are toxic (67).
Creosote constituents are also photochemically reactive (173). Photo-
chemical products of benzpyrene in aqueous solution were identified as oxidized
derivatives, but the product toxicity has not been described.
Empty containers should be thoroughly drained before disposal. Water
*
will not be effective for container rinsing. Creosote is navnirlAy seed with-
out dilution, so rinse with kerosene or other hydrocarbon solvents would leave
the rinsate as a disposal problem.
In summary, there is no suitable means of chemically degrading creosote.
Creosote and its containers should be disposed by the EPA recenq^fllad proce-
dures (Section 3) (7a).
162
-------
E.4 CHEMICAL METHODS FOR DETOXIFICATION OF WARFARIN
Warfarin is an anti-coagulent rodenticide and also an anti-coagulent drug
for humans. Warfarin, a hydroxycoumarin has an acidic group. While the feet-
acid IB slightly water soluble (4 mg/100 ml at 30°C), alkali salts are water
soluble (115). Aqueous solutions of the sodium salt, warfarin sodium, are also
used as rodenticides. Warfarin is formulated as a bait concentrate of 0.5% in
cornstarch, as finished baits of 0.025 to 0.05%, and as a 1% dust. Warfarin
sodium is available as a 40% (W/W) aqueous solution (15, 104).
Warfarin structure has two ketone groups in addition to the acidic enol
group. Its chemistry consists of reactions typical of enolic alcohols and
ketones. The enolic group reacts with alkylating agents, such as diazomethane
and acyl chlorides to yield ethers and esters. It forms typical keto-deriva-
tives. When it is warmed in methanol containing acid catalysts, such as anhy-
drous hydrogen chloride, it forms a ketal. Imines are formed with amine deri-
vatives; for example, it forms hydrazones with hydrazine derivatives. Warfarin
rearranges when heated in aqueous alkali (105).
+ CO,
Warfarin and its containers should be disposed according the the EPA
recommended procedures (Section 3) (7a). If land disposed, warfarin sodium
leaching could be reduced when it is acidified and converted to the less
soluble acid form (175).
163
-------
164
-------
APPENDFX F
PESTICIDE CONTAINER RINSE PROCEDURES
Before an empty glass or metal container is either destroyed and buried
or is sent for recycling, residual pesticide should be removed (1, 2). The
companion Handbook for Pesticide Disposal by Common Chemical Methods has
recommended the NACA triple-rinse procedure. And, for pesticides which are
susceptible to detoxification by alkaline hydrolysis, it recommended rinse
with a caustic decontaminant. Recent studies on container rinse and decontam-
ination suggest some modification of their recommendations. This section
reviews salient studies. :
Research at Oregon State University evaluated residue removal from 5, 30,
and 55 gallon containers at a drum recycling plant (176, 177). They compared
residue removal by triple rinse with water; plant processing which included
caustic rinse and immersion into caustic (1-2% sodium hydroxide) at 200°C; and
a combination of the two methods. Triple rinsing effectively removed the
residues of formulated pesticides (including phorate, disulfoton, chlordane,
2,4-D, and diazinon). The triple rinse generally removed 80% or more residue.
Slightly better reduction was achieved with caustic rinse. The OSU group
suggested that pesticide residues are removed by dissolution in water, hydrol-
ysis, and other processes. Residue fate in the caustic rinse was related to
the rate of hydrolysis: carbaryl degraded completely within 30 minutes;
diazinon had an observed half-life of 21 hours; partial degradation was
observed for disulfoton; but chlordane did not degrade.
The OSU study demonstrated inherent variation in residue reduction efficiency.
Triple rinsing (water) left the following median and range of residues in 55 gallon
165
-------
drums: phorate - 8.63 g, 3.98-15.20 g; chlordane - 3.10 g, 1.25-8.34 g;
2,4-D - 4.76, 0.86-10.90 g; and 2,4,5-T - 7.2 g, 1.67-21.71 g. Also, in a
series of 10 55 gallon phorate drums treated by a combination of triple rinse
and caustic processing, the residue reduction ranged from 77 to 95% in 9
barrels but only 37% in one barrel. The results indicate that although rinse
is effective, occasional drums could retain significantly larger residues.
They suggested one source of the variation might arise since a high percentage
of the residue (81%) was within the barrel chime (rim).
Archer evaluated the removal of 2,4-D residues from 5, 30, and 55 gallon
metal drums by rinses either with water or ethanol-acid (178). Concentrates
of 2,4-D formulated as alkanolatnine salts and as propylene glycol butyl ether
esters were examined. Simulated residues were produced by adding the estimated
volume which would be retained after completely draining the container. Table
34 summarizes salient data. Triple rinse with ethanol-acid removed more resi-
dues of the ester formulation than water rinse. A single ethanol-acid rinse
removed more of the alkanolamine salt than water, but with triple rinsing the
differences between the two solvents are small.
Hsieh and coworkers evaluated the residue removal and chemical degradation
of parathion formulated as the 4 Ib/gal emulsifiable concentrate (53). They
examined residue reduction in glass bottles (125 ml and 1 gallon) and 1 gallon
epoxy coated metal drums by rinsing with three solvents: water; alkaline deter-
gent (pH 12.45); and DIAS (250 g of disodium dioctylsulfosuccinate, 50 g of
sodium valerate, 50 g of sodium caprylate, 90 g of ethylene glycol, 80 g of
sodium carbonate and 8 g of sodium silicate in 1 liter of water then diluted
twentyfold - pH 9.88). Wash volumes were 25 ml for 125 ml glass bottles, 75 ml
166
-------
Table 34. Removal of 2,4-D from Metal Containers by
Rinse with Water or Ethanol-acid. Adapted
from Archer (178).
2,4-D Formulation
Alkanolamine Salt
Alkanolamine Salt
Alkanolamine Salt
Alkanolamine Salt
Alkanolamine Salt
Propyleneglycol
butyl ether esters
Rinse
Solvent
Water
Water
Water
Ethanol-acid
Ethanol-acid
Water
Water
Water
Water
Ethanol-acid
Ethanol-acid
Number of
Rinses
1
3
8
1
3
1
3
4
8
1
3
5 gallon drum
88.6
94.6
95.1
95.3
95.4
— _
—
—
—
—
% Residue Reduction
K
30 gallon drum
87.7
97.5
98.5
98.7
98.8
54.9
82.5
—
94.9
97.3
99.0
f\
55 gallon drum
85.6
99.3
99.6
99.7
99.7
70.3
89.9
91.8
—
94.3
95.5
(a) Rinse volume is 250 ml.
(b) Rinse volume is 750 ml.
(c) Rinse volume is 1000 ml.
-------
for .1 n«'il.l.on tflass j ug.s and 150 ml for I ^aJIon steel drums. ln.it iaJ rinse
removed about 98 to 99% of the residues from aJl containers except the metal
drums; no differences between solvents were found. A single water rinse removed
only 88% from the metal drum. Three water rinses removed 98% of the residue
from the steel drum and about 99% from the glass containers.
They evaluated hydrolysis rate of parathion by IN sodium hydroxide.
Table 35 summarizes salient details. The parathion is hydrolyzed very slowly
by aqueous alkali. The rate is accelerated by sodium hypochlorite (NaOCl),
which apparently oxidizes the parathion to paraoxon (see Appendix A-ll).
Ethanol decreased the hydrolysis time. They explained that when parathion is
in the aqueous medium it remains emulsified, but to hydrolyze it must be in
solution (see Appendix A-l). The ethanol serves to dissolve the parathion.
Table 35. Effect of Ethanol and Hypochlorite on the Hydrolysis
of Parathion in IN NaOH Solutions. Adapted from
Hsieh et al. (53).
Residual Parathion 7.
Additive
None
Ethanol
Sodium hypochlorite
Cone. %
0
25
50
2.62
5 hours
94.9
78.9
87
66.4
10 hours
90.6
59.0
NDb
61.6
26 hours
84.7
32.7
NDb
35.0
(a) Initial parathion concentrations ranged from 927 to 982 ppm.
(b) Not detected.
168
-------
In conclusion, triple rinsing will effectively reduce pesticide residues
in empty, drained containers. The residue reduction for pesticides of low
solubility will be assisted by adding ethanol to the wash solvent. Chemical
hydrolysis of the residues requires the pesticide to be dissolved. This sig-
nificantly affects the residue reduction for pesticides with a low aqueous
solubility, such as parathion and diazinon. For this reason caustic in 50%
aqueous ethanol is suggested as the wash solvent for containers of those
pesticides of low water solubility and moderate hydrolysis rate.
169
-------
170
-------
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