SUBSTITUTE CHEMICAL PROGRAM
INITIAL SCIENTIFIC
MINIECONOMIC REVIEW
MALATHION
MARCH 1975
U.S. ENVIRONMENTAL PROTECTION AGENCY
OFFICE OF PESTICIDE PROGRAMS
CRITERIA AND EVALUATION DIVISION
WASHINGTON, D.C. 20460
' EPA-540/1-75-005
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This report has been compiled by the Criteria
and Evaluation Division, Office of Pesticide
Programs, EPA, in conjunction with other sources
listed in the Preface. Contents do not neces-
sarily 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.
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PREFACE
The Alternative (Substitute) Chemicals Program was initiated under
Public Law 93-135 of October 24, 1973, to "provide research and testing
of substitute chemicals." The legislative intent is to prevent using
substitutes, which in essence are more deleterious to man and his environ-
ment, than a problem pesticide (one that has been suspended, cancelled,
deregistered or in an "internal review" for suspected "unreasonable
adverse effects to man or his environment"). The major objective of the
program is to determine the suitability of substitute chemicals which
now or in the future may act as replacements for those uses (major and
minor) of pesticides that have been cancelled, suspended, or are in litiga-
tion or under internal review for potential unreasonable adverse effects
on man and his environment.
The substitute chemical is reviewed for suitability considering all
applicable scientific factors such as: chemistry, toxicology, pharma-
cology and environmental fate and movement; and socio-economic factors
such as: use patterns and costs and benefits. EPA recognizes the fact
that even though a compound is registered it still may not be a practical
substitute for a particular use or uses of a problem pesticide. The
utilitarian value of the "substitute" must be evaluated by reviewing its
biological and economic data. The reviews of substitute chemicals are
carried out in two phases. Phase I conducts these reviews based on data
bases readily accessible at the present time. An Initial Scientific
Review and Minieconomic Review are conducted simultaneously to determine
if there is enough data to make a judgment with respect to the "safety
and efficacy" of the substitute chemical. Phase II is only performed if
the Phase I reviews identify certain questions of safety or lack of benefits,
The Phase II reviews conduct in-depth studies of these questions of safety
and cost/benefits and consider both present and projected future uses of
the substitute chemicals.
The report summarizes rather than interprets scientific data
reviewed during the course of the studies. Data is not correlated from
different sources. Opinions are not given on contradictory findings.
This report contains the Phase I Initial Scientific and Minieconomic
Review of Malathion (S-[l,2-bis(ethoxycarbonyl)-ethyl]0, 0-dimethyl
phosphordithioate). Malathion was identified as a registered substitute
chemical for certain cancelled and suspended uses of DDT. Where applicable,
the review also identifies areas where technical data may be lacking so that
appropriate studies may be initiated to develop desirable information.
The review covers all uses of malathion and is intended to be adaptable
to future needs. Should malathion be identified as a substitute for a
problem pesticide other than DDT, the review can be updated and made
readily available for use. The data contained in this report was not
intended £o be complete in all areas. Data searches ended in the Fall
iii
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of 1974. The review was coordinated by a team of EPA scientists in
the Criteria and Evaluation Division of the Office of Pesticide Programs.
The responsibility of the team leader was to provide guidance and direc-
tion and technically review information retrieved during the course of
the study. The following EPA scientists were members of the review team:
George Bagley (Chemistry), team leader; Merry L. Alexander (Chemistry);
Elsie Kelley (Pharmacology and Toxicology); Jacob W. Lehman (Fate and
Significance in the Environment); E. David Thomas, Ph.D. (Registered
Uses); Jeff Conopask (Economics).
Data research, abstracting and collection were primarily performed
by Midwest Research Institute, Kansas City, Missouri (EPA Contract #68-01-
2448). RvR Consultants, Shawnee Mission, Kansas, under a subcontract to
Midwest Research, assisted in data collection. American Cyanamid Company,
the manufacturer of malathion, made scientific recommendations and
additions to this report. The recommendations of the following National
Environmental Research Centers, EPA Office of Research and Development
have also been incorporated: Gulf Breeze Environmental Research Labora-
tory, Gulf Breeze, Florida; National Water Quality Laboratory, Duluth,
Minnesota; Southeast Environmental Research Laboratory, Athens, Georgia.
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GENERAL CONTENTS
List of Figures
List of Tables
Part I.
Part II.
Subpart A.
Subpart B.
Subpart C.
Subpart D.
Summary ........
Initial Scientific Review
Chemistry ........
Pharmacology and Toxicology
Fate and Significance in the Environment
Production and Use
Page
vi
vii
1
15
15
62
124
189
Part III.
Minieconomic Review
233
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FIGURES
No. Page
1 Production and Waste Schematic for Malathion 19
2 General Scheme for Multiple Residues 27
3 Analytical Scheme for Chlorinated (Nonionic) and
Organophosphate Residues 28
4 Effect of Carriers on the Stability of
Malathion Dust Concentrates 37
5 Chemical and Photochemical Transformations of
Selected Pesticides in Aquatic Systems 40
vi
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TABLES
No. Page
1 Raw Materials and By-Products in the Manufacture of
Malathion 18
2 Potentiating Action of Some Organophosphates on
Malathion 34
3 Dietary Intake of Malathion and Total Organophosphates . . 50
4 Average Incident and Daily Intake of Malathion 50
5 Malathion Residues in Cereals and Grains for Human Use . . 52
6 Malathion Residues in Raw Domestic Grain Products for
Animal Consumption • 52
7 Distribution of Malathion Residues in Grains and Cereal
by Quantitative Ranges (ppm) ......... 53
8 U.S. Tolerances for Malathion on Raw Agricultural
Commodities 55
9 Malathion Tolerances Established by FAO/WHO 57
10 Acute Oral Toxicity of Malathion to Rats 66
11 Acute Toxicity of Malathion for Rats via Routes Other
Than Oral 68
12 Subacute Oral Toxicity Test in Rats Fed Malathion 69
13 Chronic Toxicity of Malathion to Rats 72
14 Acute Oral Toxicity of Malathion to Mice 73
15 Acute Toxicity of Malathion to Mice - Routes Other
Than Oral 74
16 Acute Toxicity of Malathion to Guinea Pigs 74
17 Subacute Dermal and Inhalation Toxicity of Malathion to
Guinea Pigs ........ 75
.. N
18 Spraying Conditions Related to Dermal and Respiratory
Exposure of Workers to Malathion 108
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TABLES (Continued)
$°JL. Page
19 Acute Toxicity of Malathion to Fish 127
20 Common and Scientific Names of Fish Used in Controlled
Toxicity Tests With Malathion 129
21 Subacute and Chronic Toxicity of Malathion to Fish .... 130
22 EC5Q (immobilization) Values (ppb) of Malathion
to Zooplankton . 136
23 LC5Q Values (ppb) of Malathion to Benthic
Invertebrates . * 137
24 Subacute Toxicity of Malathion to Avian Species 148
25 Major Insect and Mite Pests Against Which Malathion
is Recommended 191
26 Registered Uses, Dosage Rates, Tolerances, and Use
Limitations for Commonly Used Malathion Formulations . . 194
27 Registered Uses of Malathion ULV Concentrate ....... 214
28 Estimated Uses of Malathion in the U.S. by Regions
and Categories, 1972 220
29 Farm Uses of Malathion in the U.S. in 1964, 1966, 1971
and 1972 221
30 Estimated Farm Uses of Malathion in the U.S. by Regions
and Major Crops and Other Uses, 1972 222
31 Malathion Uses in California by Major Crops and Other
Uses, 1970*-1973 227
32 . Use of Malathion in California in 1972, by Crops,
Applications, Quantities, and Acres Treated 229
33 Use of Malathion in California in 1973, by Crops,
Applications, Quantities, and Acres Treated 231
34 Malathion Efficacy Testing Results on Boll weevils .... 238
viii
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TABLES (Continued)
No. Page
35 Malathion Efficacy Testing Results on Spider Mites .... 238
36 Tield and Benefit Analysis Results of Malathion on
Selected Cotton Pests 240
37 Tield and Benefit Analysis Results of Malathion on
Sorghum Greenbugs 241
38 Malathion Treatment Results on Sorghum Midge 242
39 Malathion ULV Aerial Applications for Cherry Fruit Fly
Control (The Dalles, Oregon, 1969, Cherries Harvested
18 July) 246
40 Malathion ULV Aerial Applications for Cherry Fruit Fly
Control (Eugene, Oregon, 1969) 246
. **•
41 Control of the Tarnished Plant Bug on Strawberries
with Malathion 246
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PART I. SUMMARY
CONTENTS
Page
Production and Use 2
Pharmacology and Toxicology ............. 3
Food Tolerances and Acceptable Intake 8
Environmental Effects 8
Specific Hazards of Use 12
Limitations in Available Scientific Data 12
Efficacy and Cost Effectiveness 12
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This section contains a summary of the "Initial Scientific and
Minieconomic Review" conducted on malathion. The section summarizes
rather than interprets scientific data reviewed.
Production and Use
Malathion (S-[1,2-bis(ethoxycarbony1)-ethyl]0,0-dimethyl phosphor-
dithioate) has a very broad spectrum of effectiveness against insects
and mites. The estimated U.S. production of malathion in 1972 is 24
million pounds as active ingredient (AI). American Cyanamid Company,
Warners, New Jersey, is the only domestic manufacturer of malathion.
Only two reactions are involved in the manufacture of malathion.
In the first (1),0,0-dimethyl dithiophosphoric acid is made by react-
ing methanol and phosphorus pentasulfide. In the second reaction (2),
the acid is reacted with diethyl maleate to produce malathion :
S
P2S5 + 4CH3OH > 2 (CH30)2PSH + H2S (1)
S S
II II
(CH30)2PSH + HC-COOC2H5 > (CH30)2PSCHCOOC2H5 (2)
HC-COOC2H5 CH2COOC2H5
The chemistry of malathion has been the subject of extensive study.
Hydrolysis, the most important decomposition reaction, has received the
most intense investigation. Depending upon the reaction conditions,
hydrolysis can occur via several different pathways leading to a
variety of products. In aqueous systems, the rate of hydrolysis is pH
dependent; "instantaneous" hydrolysis at pH 12; 507» hydrolysis in 12 hr
at pH 9; and no hydrolysis detected after 12 days in slightly acid
solution (pH 5 to 7). In neutral aqueous solutions 59.3% hydrolysis
was reported after 1 week.
Malathion is readily oxidized to malaoxon by a number of mild
oxidizing agents, and is also degraded by ultraviolet radiation. On
prolonged contact with iron, malathion is reported to decompose and
completely lose insecticidal activity.
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Malathion is available for domestic use in a variety of different
formulations in which it is the only active ingredient. These in-
clude eraulsifiable liquids, wettable powders, dusts, solutions, and
concentrates for low volume (LV) and ultra-low volume (ULV) applications,
In addition, a number of liquid and dry formulations are available that
contain malathion in combination with other insecticides and/or fungi-
cides.
The most widely used formulations of malathion are the ULV con-
centrates containing 95% active ingredient (9.7 Ib Al/gal), applied
by ground or air equipment; and the 57% (5 Ib AT/gal) emulsifiable
liquid.
It is estimated that about 16.2 million pounds of malathion (as
AI) were used in the United States in 1972. Consumption of malathion
by category of use in 1972 is estimated to have been: agriculture - 5
million pounds; industrial and commercial uses - 4 million pounds;
government agencies - 2.2 million pounds; and home and garden uses -
5 million pounds. Agricultural use of malathion in 1972, by region,
is estimated to have been: Northeastern States - 0.2 million pounds;
Southeastern States - 1.05 million pounds; North Central States - 1
million pounds; South Central States - 1.05 million pounds; North-
western States - 0.7 million pounds; and Southwestern States - 1
million pounds.
Pharmacology and Toxicology
Toxicity
The largest dose of malathion that has been reported as nonfatal
to humans is 200 mg/kg of body weight; the smallest fatal dose reported
is 71 mg/kg of body weight. The threshold of incipient toxicity to
humans appears to be 24 mg of malathion. The estimated acceptable
daily intake for man is 0.02 mg/kg of body weight.
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Rats have been fed.on a diet that contained up to 5,000 ppm of malathlon
for 2 years without mortality, although body weight gain was reduced
and blood chollnesterase levels were depressed. When the dosage was
raised to 20,000 ppm, there were marked reductions of growth, food In-
take, and blood chollnesterase activity. A "no effect" level of 100
ppm has been established for malathlon In rats.
Acute oral toxlclty for a number of species Is summarized as
follows:
Acute Oral Toxlclty of Malathlon
Species LDsn value (me/kg)
Rat 1,000-1,845
Mouse 720-3,321
Guinea pigs 570-815
Chickens
Adult > 850
1 year old 150-200
3 to 4 weeks 200-400
2 to 3 weeks 370
Cats > i500
Rabbits > 900
Sheep < 150
Cattle 200-560
Calves (dairy) 80
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A summary of the toxicity of malathion via routes other than oral
is- given below:
Toxicity of Malathion Via Routes Other Than Oral
Value
Species
Rat
Mice
Routes of entry
Intraperitoneal
Intravenous
Subcutaneous
Dermal
Inhalation
Intraperitoneal
Inhalation
Guinea pigs Intraperitoneal
Dermal, 24-hr
exposure
Inhalation, 5 ppm
4 weeks
Dogs Intraperitoneal
Intravenous
Inhalation, 5 ppm
4 weeks
Rabbits Dermal
Measurement
LD50 (mg/kg)
LD50 (mg/kg)
LD50 (mg/kg)
LC5o 8 hr
LD50 (mg/kg)
LC50 8 hr
(mg/mj)
LD (mg/kg)
(mg/kg)
LD50 (mg/kg)
LD50 (mg/kg)
LD50 (mg/kg)
Male
750
50
1,000
> 4,444
Female
1,000
50
--
> 4,444
> 60 > 60
420 to 815
> 15
500
420 to 474
> 12,300
No effect
1.51 ml/kg*
> 430 to < 600
Blood cholinesterase
activity reduced
2,400 to 6,150
* Of a 95% malathion solution.
In summary, malathion has a low oral toxicity in all mammals
except cattle and sheep. The reason for the apparent sensitivity of
cattle and sheep was not determined. There does not appear to be a
toxic differentiation due to sex, such as found with some other
organophosphate pesticides.
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Malathion has a low toxicity by all the routes that have been
investigated with the exception of intravenous injection and in-
halation. This observation leads to the question of the role of
malathion entry to physiological systems.
Metabolism
Malathion is readily absorbed from the gastrointestinal tract by
passive transport, but is only slowly absorbed through the skin. Very
low concentrations of malathion are widely distributed in tissues.
Concentrations in bone and liver are somewhat higher. There is no
evidence of long-term accumulation of malathion (or malaoxon) in
body tissues. Malathion metabolites are mostly excreted in urine.
In mammals these urinary metabolites are mainly mono- and di-acids
of malathion. The principal fecal metabolite is dimethyl phosphate.
Malathion requires activation for anticholinesterase activity by
conversion from the thiol to its oxygen analogue. Activation is
at the microsomal level and requires NADH^s Mg++, and nicotinamide.
Malathion is degraded by phosphatases and carboxylesterases or alies-
terases. Malathion toxicity is potentiated by EPN, TOTP, and pos-
sibly some other organophosphates. Potentiation has been postulated
to be mediated via carboxylesterase or aliesterase inhibition, but
the mechanism is not fully understood. Some evidence indicates
that potentiation may be via multiple mechanisms.
Reproduct ion
The hatchability of hen eggs injected with sufficient malathion
dissolved in 0.02 ml acetone to yield 25, 100, 200, 300, 400, and
500 ppm malathion was reported to be 85%, 87%, 62%, 71%, 42%, and 6%,
respectively. Eggs injected with sufficient malathion dissolved in
0.02 ml corn oil to yield concentrations of 50, 100, and 200 ppm
showed hatchability of 84%, 9%, and 9%, respectively.
Malathion has been reported to have little, if any, effect on
the metabolism and motility of boar spermatozoa.
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Teratology
The effect of intraperitoneal injections of malathion on the
rat fetus has been studied by injecting female rats with 600 and
900 rag/kg. The pregnant rats were given a single intraperitoneal
injection of malathion on day 11 after insemination. No significant
difference was found between the malathion-treated females and the
controls for: the number of dead fetuses per litter; incidences
of resorption; average weight of fetuses; average weight of
placenta; or malformations of the fetuses.
An injection of 1 mg of malathion into 4-day old hen eggs has
shown no detectable teratogenic signs, and the length of embryo
parts indicated no difference between malathion injected eggs and
controls. Furthermore, cholinesterase of the embryo was not de-
creased. Malathion injected into the egg as a level of 1 mg/egg
reduced hatchability to 70% as compared to the controls at 95% hatch-
ability, although there was no indication of parrot beak, or abnor-
malities of the legs or feathers.
The effect of malathion on the hard clam, Mercenaria mercenaria,
and the American oyster, Crassostrea virginica, has also been in-
vestigated. The TLin value for hatchability was determined to be
9.07 ppm; TI^ value for larvae survival was determined to be 2.66 ppm.
Mutagenesis
A review of the literature did not reveal any information on
the mutagenic effects of malathion.
Oncogenesis
Data was not found concerning the oncogenic effects of malathion.
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Food Tolerances and Acceptable Intake
Tolerances for malathion have been established in the United
States on 127 raw agricultural commodities. The tolerances range
from 0.1 to 8 ppm on food crops, and up to 135 ppra on forage crops.
Malathion tolerances established by the World Health Organization
range from 0.5 to 8 ppm (no ratings on forage crops).
The acceptable daily intake (ADI) for malathion was set at
the 1966 joint meeting of the FAO Committee on Pesticides in
Agriculture and the WHO Expert Committee on Pesticide Residues.
ADI for malathion is 0.02 mg/kg.
The
The results obtained from the analysis of domestic foods over
a. 4-year period by the FDA show the amount of malathion consumed
to be well below the ADI. Malathion, however, apparently does
account for the majority of the total organophosphates present in
foods (0.00013 of the total 0.00017 mg/kg body weight/day) .
Environmental Effects
Available data shows that malathion is highly toxic to fish and
benthic invertebrates, and the potential for damage to these populations
exists when malathion is used at insecticidally effective rates of appli-
cation over or near aquatic environments. A brief summary of the toxicity
of malathion to aquatic species is as follows:
for Malathion for Fish
Hour
ppm
Black bullhead
Bluegill
Carp
Cirrhina mrigala
Danio sp.
Fathead minnow
Goldfish
96
48
48
48
48
48
96
12.9
0.12
10.0
7
13.5
24.0
10.7
Green sunfish
Guppy
Labeo fimbreatus
Labeo rohita
Largemouth bass
Rainbow trout
Tilapia
Hour
ppm
48
48
48
48
48
96
48
0.70
0.88
8.5
8.0
0.28*
0.170
5-8.3
* Twenty percent emulsifiable concentrate.
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Malathion for Benthic Invertebrates (ppb)
Species
Stonef lies
Pteronarcys
californica
Acroneuria
pacifica
Pteronarcel la
badia
Claassenia
sabulosa
Caddis flies
Arctopsyche
grand is
Hydropsyche
californica
Mayflies
Ephemerella
grandis
Baetis sp.
Amphipods
Gammarus
lacustris
Temperature
(°F)
60
60
52-53
60
60
60
60
51-54
51-54
48-50
70
70
70
Time
(hr)
24
48
48
24
48
24
48
96
96
96
48
24
48
Value
35
20
12
10
60
13
6
32
22.5
100
6
3.8
1.8
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Reports on fish toxicity of malathion degradation products are
somewhat contradictory. In view of the large-scale use of malathion
(including use over and near aquatic environments); it is apparent
that more information on the identification, toxicity, persistence,
and fate of these degradation products in the aquatic environment is
needed.
Most species of wildlife exposed to malathion applications at
dosage rates required for insect control apparently tolerate the
insecticide rather well. Effects on wildlife outside of target areas
appear to be minimal. Mice and quail exposed to ground applications
of ULV malathion at one and 10 times the recommended rate (1.5 and 15.0
fluid oz/rain) did not exhibit any poisoning symptoms. Caged quail
exposed to raalathion spray (12 to 16 fluid oz/acre) in the field
and fed on sprayed feed showed small differences in growth rates com-
pared to untreated birds.
The subacute oral toxicity of malathion to avian species is as
follows:
5-Day
Species (ppm)
Bobwhite quail 3,497
Japanese quail 2,128
Mallard duck > 5,000
Ring-necked pheasant 4,320
Available data indicates that in most crop-pest-predator/parasite
systems, malathion appears to have little, if any, selective toxicity
to pest species. In some instances, malathion appears to be more
toxic to beneficial than to pest insects. Malathion is highly toxic
to many beneficial parasites and predators, including lady beetles
(Hippodamia convergens), adult Orius insidiosus, the parasitic wasps
Apanteles marginiventris and Campoletis perdistinctus, and green
lacewing larvae (Chrysopa spp.).
Malathion has been shown to be one of the most toxic pesticides
to bees. The residual action on bees of ULV application of malathion
was over four times greater than that usually encountered following
dilute malathion applications.
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The scientific data on the residues and fate of malathion show
that malathion is rapidly degraded in the soil. Disagreement exists,
however, on the relative contributions of chemical versus micro-
biological processes to this degradation. All data reviewed indicates
that malathion residues in the soil are very short-lived. Degradation
in the soil is reported to be 50 to 90% in 24 hr, depending on the soil
type.
The data reviewed indicates that a number of soil microorganisms
are capable of degrading malathion. However, reports were not found
regarding to what extent, if any, such processes may occur under field
conditions. Malathion does not appear to inhibit terrestrial micro-
organisms at concentrations likely to result from insecticidal use.
Residues of malathion in natural waters are apparently degraded
rather rapidly. Concentrations of 0.5 ppm malathion in field water
samples were found to degrade with a half-life ranging from 0.5 to
10 days, depending primarily upon pH. In river water, 25% of the
original concentration of malathion remained after 1 week, 10% after
2 weeks, and no detectable concentration after 4 weeks. Under the
same test conditions, malathion remained stable in distilled water
for 3 weeks. The half-life of malathion in water is reported to be
about 1 month at pH 8 and 28°C; the range for half-life of malathion
is several days to months, depending on pH, temperature, and other
environmental conditions.
It has been reported that malathion can form relatively persistent
and possibly toxic degradation products in water. Laboratory tests
showed that malathion breaks down in water by competing pathways, one
of which yields compounds that are considered nontoxic to aquatic
organisms. The other pathway, which is favored in colder water (35°F),
results in the formation of malathion acids which may possess some
of the toxic properties of malathion and appear to be more persistent
in the environment than the parent compound.
The effect of water on the adsorption of malathion onto five
montmorillonite systems has been studied. Malathion penetration of
the interlayer regions of montraorillonite was very slow below 30%
relative humidity. At relative humidities exceeding 40%, malathion
penetrated within minutes and was adsorbed as a double layer. The
mechanisms of adsorption was through a hydrogen bonding interaction
between the carbonyl oxygen atoms and the hydration water shells of
the saturating cations. Changes in the hydration status of the clay
system produced marked reversible alterations in the spectrum of ad-
sorbed malathion that were believed due to orientation and interaction
effects. No degradation of adsorbed malathion was observed.
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The available data indicates that, under field conditions, malathion
is degraded by chemical as well as by biological mechanisms. The data,
for the most part, indicates that chemical degradation is more important
under field conditions. The data also indicates that volatilization does
not appear to be a major transport mechanism by which malathion may move
away from target sites after application.
Malathion has been rated using an index designed to determine the
propensity of pesticides for volatilization and leaching under simulated
field conditions for loam soils at 25°C and an annual rainfall of 59 in.
By this method, malathion rated a volatilization index of 2, indicating
an estimated median vapor loss from treated areas of 1.8 Ib/acre/year.
This index number indicates that the propensity for volatilization of
malathion from treated fields is in the intermediate range, compared
to many other pesticides. Malathion rated a leaching index number of
2 to 3, indicating movement of 6 to 10 in. through the soil.
No data was found on the metabolism or the residues of malathion
in or on nontarget higher plants.
There was also no data found dealing directly with the possible
bioaccumulation or biomagnification of malathion.
Specific Hazards of Use
The data compiled during the subject review has not shown any
of the specific uses of malathion to be substantial hazards to man and
the environment. This lack of substantiation is significant in light
of the extensive use and scientific investigation of malathion.
Limitations in Available Scientific Data
The review of scientific literature was based on available sources,
given limitations of time and resources. Data was not found in a number
pertinent areas: 1) the route and rate of metabolism of malathion in
the environment; 2) the nature, persistence and toxicity of major degrada-
tion products of malathion to fish and other nontarget organisms.
Efficacy and Cost Effectiveness
The economic benefits of using malathion have been determined from
1972 cost data and from the results of field tests evaluating uses for
controlling the boll weevil on cotton, the sorghum midge and greenbug on
sorghum, the potato leafhopper on soybeans and potatoes, the sugar beet
maggot on sugar beets, the corn rootworm on corn, the alfalfa weevil
12
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on alfalfa, the tarnished plant bug on strawberries, the Mexican bean
beetle on beans, aphids on peas and potatoes, and the hornfly and
other insect pests on cattle. However, the data is incomplete and
should be looked upon with caution.
Malathion provides effective control for the boll weevil and
two-spotted spider mites on cotton. However, it is not highly toxic
to the tobacco budworm or bollworm and is not recommended by many
states for control of these pests on cotton. Malathion is often
used with methyl parathion to control all of these pests. Economic
benefits from the use of malathion ranged from $6.70 to $700.20/
acre when compared to untreated test plots.
Over 90% seasonal control of the greenbug on sorghum plants can
be achieved with malathion. Excellent control of the sorghum midge
has also been proven. However, the latter pest is not a major factor
due to early uniform planting of sorghum plants. Economic benefits
based on experimental tests of greenbug control comparing malathion
treated plots to untreated plots ranged from $4.30 to $32.10/acre in
the control of the greenbug.
Damage from the potato leafhopper on soybeans has lead to yield
declines averaging 25.7 bushels/acre. Malathion at 1.0 Ib/acre was
used by Iowa farmers to control this pest and resulted in an economic
benefit of $88.50/acre.
One test of malathion, applied to sugar beets for control of
the sugar beet maggot, resulted in a 13% yield increase, equal to an
economic benefit of $51.00/acre.
Malathion has shown mixed results for control of the alfalfa
weevil. One author concluded that it was effective in warm weather
but performed poorly in wet and cool weather. Economic benefits ranged
from no increase to an increase of $54.40/acre.
Use of malathion for controlling grasshoppers on rangeland averaged
82 to 95%, resulting in an economic benefit of $5.40/acre.
Infestation rates from the cherry fruit fly in malathion-treated
cherry fields in Oregon ranged between 0 and 0.57%. Untreated fields
showed infestation rates as high as 10.06%. Yield data were unavailable
from this test.
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An application of 1.0 Ib/acre of malathion 14 days after appli-
cation of dimethoate has been shown to be an effective control for
the tarnished plant bug on strawberries. Economic benefits ranges
from $156.60' to $805.20/acre as the result of yield increases from
the use of malathion.
Malathion effectively controlled the mexican bean beetles and
yielded an economic benefit of $443.50/acre when applied to snap
beans.
Malathion has been shown to give effective control of the hornfly
on cattle. Weekly applications during the hornfly season have resulted
in weight gains of 30 to 70 Ib/animal. This use of malathion produces
economic benefits ranging from $6.40 to $22.00/head.
Non-agricultural uses are significant in terms of volume (66%)
although benefit estimation is very difficult because of the more
abstract nature of aesthetic recreational and health benefits. The
cost effectiveness of the latter can be determined.
14
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PART II. INITIAL SCIENTIFIC REVIEW
SUBPART A. CHEMISTRY
CONTENTS
Page
Synthesis and Production Technology 17
Physical Properties of Malathion 21
Analytical Methods 23
Composition and Formulation 33
Impurities in Malathion 33
Major Formulations 34
Dusts and Wettable Powders 35
Dust Concentrates 36
Dilute Dusts 36
Wettable Powders 38
Liquid Formulations 38
Miscellaneous Formulations 39
Chemical Properties, Reactions and Decomposition Processes 39
Hydrolysis 39
Thermal Decomposition 43
Oxidation 47
Ultraviolet Radiation 47
Miscellaneous Reactions 48
Occurrence of Malathion Residues in Food and Feed Commodities .... 48
15
-------
CONTENTS (Continued)
Page
Acceptable Daily Intake 51
Tolerances 54
References 58
16
-------
This section of the scientific review of malathion (S-[l,2-
bis(ethoxycarbonyl)ethyl]0,0-dimethyl phosphorodithioate) contains a
detailed review of available data on its chemistry and presence in
foods. Seven subject areas have been examined: synthesis and pro-
duction technology; physical properties of malathion; composition and
formulation; chemical properties, reactions and decomposition proc-
esses; occurrence of residues in food and feed commodities; acceptable
daily intake; and tolerances. The section summarizes rather than
interprets scientific data reviewed.
Synthesis and Production Technology
Malathion is manufactured by only one company in the United States,
American Cyanamid, in Warners, New Jersey. Figure 1 is a production
and waste schematic for malathion manufacture; Table 1 lists raw mate-
rials, and their sources and by-products, and wastes and their dispo-
sition as described by the company in 1971.
Only two reaction steps are involved in the manufacture of mala-
thion. In the first reaction (1), 0,0-dimethyl dithiophosphoric acid
(DMTA) is made by reacting methanol and phosphorus pentasulfide. In
the second reaction (2), the acid is reacted with diethyl maleate (DEM)
and/or diethyl fumarate (DEF) to produce malathion.
o
4CH3OH >2(CH30)2PSH + H2S (1)
S S
(CH30)2PSH + HC-COOC2H5 > (CH30)2PSCHCOOC2H5 (2)
HC-COOC2H5 CH2COOC2H5
Suitable conditions for manufacture are specified in several U.S.
I/
patents. In one patent, Cassaday (1951)— uses an aliphatic tertiary
amine catalyst, such as triethylamine, in the first reaction. The
amount of amine is usually in the range from 0.2 to 2.0% of total
weight of reactants. Cassaday also suggests use of an antipolymeriza-
tion agent such as hydroquinone to guard against polymerization of the
maleate or fumarate compound.
I/ Cassaday, J. T. (to American Cyanamid Company), U.S. Patent No.
2,278,652 (18 December 1951).
17
-------
Table 1. RAW MATERIALS AND BY-PRODUCTS
IN THE MANUFACTURE OF MAIATHION
Raw materials
Material Received from
1.
2.
3.
4.
5.
¥2^5 Three local sources
CH3OH
Diethyl Linden, New Jersey
maleate
Toluene Local
Caustic
Received by
Truck, in tote
bins
Rail, tank cars
Pipeline
Tank truck
Tank truck
Storage
Tote bins
Bulk
Bulk
Bulk
Bulk
Material
Form
Gas
Reaction by-products
Amount produced
(Ib/lb AI)
0.052
Material
1. Active ingre-
dient
2. Solvents
toluene
3. Liquid wastes
and spills
Disposition
Recovered as sulfur in new
plant with good
Other process wastes and losses
Form
Aqueous
Liquid and
some vapor
Amount produced
(Ib/lb AI)
Unknown
Unknown
Disposition
Barge to deep sea
Liquid barged to sea;
vapor flared
To holding pond even-
tually barged to the
sea
Source: Lawless, E. W., and T. L. Ferguson (Midwest Research Institute),
R. von Rumker (RvR Consultants), The Pollution Potential in
Pesticide Manufacturing, Cor the Environmental Protection Agency,
Contract No. 68-01-0142 (January 1972).
18
-------
"2«>5 ^ Dithio ^
Toluene — »- Unit
u c _ To Clauss Sulfur
enser -»- H2S — *- Recoyery p,Qnt
MA*
1 C!li. _ T_ A 1
A ^^~~—~~'^ •— — ^ i uim ^ iu /-vjjjjiuvcu
^ Distillation Filter Cake Landfill
!**> i . .1. •• — — — — ^^— - • < — • Stfinnn
iH2
-------
A fairly recent patent by Backlund et al. (1969)— describes the
currently used method, which was -developed to reduce the amount of
diethyl fumarate in the final technical grade material. Di'ethyl
fumarate has been found to cause skin sensitization or irritation to
some people. This new process reduces the amount of diethyl fumarate
from the 1 to 4% range to less than 0.5%, and it also increases produc-
tion yields. The process is described as follows:
"There is initially reacted phosphorus pentasulfide and the
methanol in the presence of a suitable solvent, such as dioxane,
benzene, or toluene, at an elevated temperature, typically between
about 170 and 190°F, and preferably between 175 and 185°F, to prepare
0,0-dimethyl dithiophosphoric acid. The reaction mixture is next re-
acted with diethyl maleate, usually in a mole ratio of from about 1.02
to 1.15, and preferably from 1.02 to 1.10 moles of 0,0-dimethyl dithio-
phosphoric acid to 1.0 mole of diethyl maleate. The reaction is ter-
minated when the desired reaction product, namely, crude malathion,
contains approximately between 10 and 25% of unconverted reactants.
This terminal point is readily determined by intermittently analyzing
the condensation or reaction mixture. Condensation reaction tempera-
ture is maintained from about 175 to about 225°F and preferably be-
tween about 190 to about 200°F. During the initial reaction period,
pressure is reduced from about 760 mm Hg to between about 20 mm Hg
and 30 mm Hg. The residence time for effecting partial or incomplete
reaction is approximately 3 hr, during which time essentially all of
the solvent is stripped off and recovered.
"Crude malathion reaction mixture containing between 10 and 257o
of unconverted reactants is further subjected to heating at between
about 250 and about 360°F, and preferably from 280 to about 320°F,
and a reduced pressure of about 1 mm Hg to about 30 mm Hg in a low
retention time-evaporation still, such as a wiped-film or falling
film evaporator. This step is singularly critical so that most of
the unconverted reactants and a small amount of malathion can be
stripped off or removed from the mixture while avoiding the conver-
sion to degradation products. The stripped overheads from the evap-
orator, which contain the unconverted reactants and some malathion,
are then recycled to the reaction vessel for make-up with additional
diethyl maleate and 0,0-dimethyl dithiophosphoric acid. Thereafter,
I/ Backlund, G. R., J. F. Martino, and R. D. Divine (to American
Cyanamid Company), U.S. Patent No. 3,463,841 (25 August 1969).
20
-------
•' * -'
the bottoms containing desired malathion are washed with an aqueous
sodium carbonate solution to eliminate residual acidic impurities,
water washed and, finally, steam-stripped to yield dry malathion
having minimum purity of about 97% and containing less than 0.5%
of diethyl fumarate.
"Malathion containing less than 0.5% of diethyl fumarate can,
if desired, be readily prepared from the above-recovered steam-
stripped product. The latter may be treated with an aqueous solu-
tion containing sodium sulfide, sodium sulfite, potassium sulfide,
potassium sulfite, ammonium sulfide or ammonium sulfite to estab-
lish a pH of at least 7, and preferably between 7.1 and 7.5. The
organic phase containing malathion of less than 0.1% diethyl fumarate
content is then separated from the aqueous layer."
This patent (Backlund et al., 1969) also states that yields of
malathion are 94%, based on diethyl fumarate, and 83%, based on phos-
phorus pentasulfide.
Physical Properties of Malathion
Chemical Name; S-[l,2-bis(ethoxycarbonyl)ethyl]0,0-dimethyl phosphoro-
dithioate)
Common Name; Malathion
Trade Names; Cythion, Emmatos, Emmatos Extra, Fyfanon, Karbofos,
Kop-Thion, Kypfos, Malaspray, Malamar, MLT, Zithio,
Mercaptathion, Carbofos, Maldison
Pesticide Class: Nonsystemic insecticide and acaricide; organophos-
phate
Structural Formula:
'"X3 o
,0"" XS-CH-C-OC2H5
-oHc
b 25
Empirical Formula: GinHig°gPS2
21
-------
Molecular Weight; 330.36
Analysis: C 36.35%; H 5.80%; P 9.38%; S 19.41%; 0 29.06%
Physical State: Clear liquid, may be colorless, yellow, amber or
brown
Characteristics; Technical grade material is a minimum 95% purity.
It has a slight characteristic mercaptan-like odor
resulting from as much as 30 ppm impurity as methyl
mercaptan. Malathion insecticide concentrates may
gel if stored in contact with iron, terneplate, or
tin plate for a prolonged period. No gelation has
been observed in finished malathion insecticide
aerosols or other formulations containing 5% or
less of the insecticide. Malathion insecticide
concentrates may solidify if stored at temperatures
near 32°F. Normal viscosity can be restored by
allowing drums of malathion to warm up to 40°F.
(Cyanamid International!./).
Melting Point; 2.85°C
Boiling Point: 156 to 157°C at 0.7 mm Hg (slight decomposition)
Vapor Pressure: 0.00004 mm Hg at 30°C
Specific Gravity; 1.2315 at 25°C
Density; 10.25 Ib/gal (1.2 kg/liter)
Refractive Index: n2,5 1.4985
Viscosity: At 40°C, 17.57 centipoises (0.176 dyne/sec/cm2)
At 25°C, 36.78 centipoises (0.368 dyne/sec/cm2)
Flash Point (Tag Open Cup): Greater than 320°F (160°C)
Solubility: In water at 25°C, approximately 145 ppm. Completely solu-
ble in most alcohols, esters, high aromatic solvents,
ketones and vegetable oils. Poor solubility in ali-
phatic hydrocarbons.
if Cyanamid International, Malathion Insecticide for Adult Mosquito
Control (Bulletin), Wayne, New Jersey.
22
-------
Analytical Methods
This subsection reviews malathion analytical methods and the
most significant of many primary information sources on the methods.
The following information sources are described: (1) the Pesticide
Analytical Manual (PAM), vols. I, III/, (2) Official Methods of
Analysis of the Association of Official Analytical Chemistsj/,
(3) Analytical Methods for Pesticides and Plant Growth Regulators!/.
The Pesticide Analytical Manual - The .Pesticide Analytical Manual
(PAM) published by the Food and Drug Administration, provides pro-
cedures and methods used by the FDA laboratories to examine food
samples for the presence of pesticide residues. The PAM is published
in two volumes. Volume I contains procedures for multi-residue
methods (for samples of unknown history which may contain more than
one pesticide). Volume II contains analytical methods used for specific
pesticide residues and for specific foods.
Official Methods of Analysis of the Association of Official Analytical
Chemists - The Association of Official Analytical Chemists (AOAC)
publishes an authoritative methods manual about every 5 years. The
manual is designed to provide both research and regulatory chemists
with reliable methods of analysis. The reliability of the methods
must be demonstrated by a published study showing the reproducibillty
of the method by professional analysts.
When an AOAC method is adopted for the first time it is published
as "Official First Action." This designation serves notice that final
adoption is pending, and permits an opportunity for any further study
that may be deemed appropriate.
Methods that have performed successfully for at least 1 year are
raised to the status of "Official Final Action."
A few methods are adopted as "Procedures." Such methods are
generally sorting or screening methods or well-established types of
examinations, or auxiliary operations, such as sampling or preparation
of a sample, which may not have been subjected to collaborative study.
If U.S. Department of Health Education, and Welfare, Food and Drug
Administration, Pesticide Analytical Manual. 2 vols. (1971).
27 Association of Official Analytical Chemists, Official Methods of
Analysis of the Association of Official Analytical Chemists,
llth ed., Washington, D.C. (1970).
3/ Zweig, G., and J. Sherma, Analytical Methods for Pesticides and
Plant Growth Regulators, Vol. VI; Gas Chromatographic Analysis,
Academic Press, New York (1972).
23
-------
Analytical Methods for Pesticides and Plant Growth Regulators, Volume
VI, Gas Chromatographic Analysis - Chapter 6 of this text consists of
an extensive and detailed review of specific and multi-residue
analytical methods for organophosphate pesticides. This reference
provides important information not available in AOAC's "Methods of
Analysis" or the PAM such as (1) a comparison of nine procedures for
extracting phosphorus insecticides and their metabolites from field-
treated crops, (2) a review of procedures for extracting organophosphate
pesticides from water samples, (3) a review of insecticide recoveries
from vegetables, (4) a review of various clean-up procedures, (5) a
description of various detectors, (6) extensive data comparing the
relative retention times of various pesticides on various column
materials, and (7) a review of the sensitivity of various gas chromato-
graphic systems.
Multi-Residue Methods -
Multi-residue methods for malathion are described in the AOAC's
methods manual and PAM, Volume I. Zweig and Sherma (1972) have
compiled a detailed review of gas chromatographic residue analyses.
AOAC Methods - One of the AOAC methods, a general method for "chlorinated
and phosphated pesticides," is an "Official First Action" and applies
only to apples and lettuce. A second AOAC multi-residue method applies
only to "phosphated pesticides" (in kale, endive, carrots, lettuce,
apples, potatoes, and strawberries). This second method is also an
"Official First Action" and involved a sweep codistillation cleanup
for the organophosphate residues. (The cleanup is not adequate for
electron capture detectors; KC1 thermionic detectors must be employed.)
Also described in AOAC methods manual is a single sweep oscillographic-
polarographic confirmation method.
24
-------
The following AOAC multi-residue method is used for chlorinated
and phosphated pesticides: a. thoroughly mixed sample is extracted
with acetonitrile. Aliquots of the acetonitrile solution are diluted
with water and the pesticide residues are extracted into petroleum
ether. The residues are purified by chromatography on a Florisil
column and are eluted from the column with mixtures of petroleum and
ethyl ethers. The first eluate (6% ethyl ether in petroleum ehter)
contains some chlorinated pesticides and some phosphated pesticides.
Methyl parathion, parathion, and diazinon are obtained in a second
eluate (15% ethyl ether in petroleum ether). A third eluate (50%
ethyl ether in petroleum ehter) contains malathion. The eluates are
concentrated, and the residues are determined by gas chromatography
and identified by combinations of gas, thin-layer, or paper chromatography.
PAM Procedures - The PAM multi-residue methods (PAM, 1971) apply to
the wide variety of foods tested by the FDA. However, the multi-
residue methods are not capable of detecting and measuring all
pesticides. Analytical schemes used in the detection of malathion
are shown in Figures 1 and 2. The various parts of the schemes
shown in Figures 1 and 2 are outlined in detail in the PAM. (The
numbers refer to the chemical numbering system of PAM; the chapter
numbers also refer to PAM.)
Malathion is more than 80% recovered in the 50% ethyl ether in
petroleum ether fraction from the Florisil column. Over 80% recovery
is achieved from nonfatty foods (no data are available for fatty
foods).
Relative retention times of malathion are presented in various
column packing in the illustration that follows:
25
-------
Column
packing
10% DC 200 on
Gas-Chrom Q
(or Anakrom Q)
15% QF-1,
10% DC 200 on
Gas-Chrom Q
Electron Capture Detector
Retention time
relative to aldrin
(ratio)
0.87
1.48
Response
(ng for 1/2 FSD*
at 1 x IP"9 AFS**)
20-30
20-30
Sulfur Detector
Column
packing
10% DC 200 on
Gas-Chrom Q
15% QF-1,
10% DC 200 on
Gas-Chrom Q
Retention time
relative to sulphenone
(ratio)
0.71
0.55
Response
(ug for 112 FSD"
64 ohms)
0.75
0.75
* FSD = Full scale deflection.
** AFS = Amps, full scale.
26
-------
Sample Preparation
141
Guideline* for
Compositing
142
1
Chlorinated (nonionic)
210
Organophosphates
230
See ScAeme 162**
Extraction and
Cleanup
Chapter 2
1
I
Gas Chroraatography
(quantitative)
Chapters
1
Thin Layer
Chromatography
(femi • quantitative)
Chapter 4
Determinative
Methods • other
Chapter 5
Confirmatory Tests
Chapter 6
Chlorinated (ionic)
220
See Scheme 163
* The numbers refer to the decimal numbering system of PAM.
Chapter numbers also refer to PAM.
** Scheme 162 is presented in Figure 2.
Source: PAM (1971).
Figure 2. General scheme for multiple residues*
27
-------
Chlorinated (Nouionic) 210
Organophosphatcs 230
I
Proximate Percentage Water
and Fat in Foods and Feeds 202
J_
_L
Fatty Foods
211 231
Non Fatly Foods
212 232
Extraction of Fat
211.13
1
Acetonilrile
Partitioning
211.14
1
Extraction and
Partitioning
212.13
Florisil Column
211.15
I
1
L .,
T
2nd Florisil
Column
211. 16 a ~~— *.
_ __ 1
r
1 ._ .
Acid-Celite
Column- ^,
211.16 b --'"'
& 2nd Florisil
Column
— -T -J
1
Gas Chromatography
Electron Capture and Thermionic
rilial n»t»l«fi/in ^vct»m ^91
Gas Chromatography
Electron Capture Detector
311
\
Thin Layer Chromatography
Chlorinated 410
Organophosphates 430
I1CM. PI...I.
]
r~
•
— -i
~'~" L.
i
^ j,
£ i
' %
** •--
\ r
*% i
N
I-
i
i
L>
2nd Florisil
Column
211.16 a
IILVIIV.!
_, i •
MgO-C elite
Column
211.16 c
...
Alkaline
Hydrolysis
211.16 d
& UgO-Celite
Column
1
"1
i
i
1
i
i
i
1
1
1
|
* The numbers refer to the decimal numbering system of PAM. The
primary analytical scheme is in bold type. Additional cleanup
and/or quantitation schemes are in italics.
Source: PAM (1971).
Figure 3. Analytical scheme for chlorinated
"" ^^
(nonionic) and organophosphate residues
28
-------
Potassium Chloride Thermionic Detector
Retention time
Column relative to parathion Response
packing (ratio) (mg for 1/2 FSD*)
10% DC-200 on 0.90 5
Chromosorb W-HP
(or Gas Chrom Q)
15% QF-1 + 10% 0.79 3
DC 200 on Chromosorb
W-HP (or Gas Chrom Q)
* FSD = Full scale deflection.
The PAM does not provide response data for flame photometric detec-
tors. However, this type of detector is now widely used for the analysis
of organophsophate residues, primarily because of the high degree of
specificity in detecting phosphorus compounds. A review of these and
other detectors is provided by Zweig and Sherma (1972).
Residue Analysis Principles -
Both AOAC "Methods of Analysis" (1970) and PAM (Vol. II) describe
methods for the specific analysis of malathion residues. Zweig and
Sherma have also provided a review of specific residue analytical
methods for malathion.
AOAC Method (Official First Action) - According to the AOAC method for
specific analysis of malathion residues, malathion is extracted with
carbon tetrachloride or 2-propanol-carbon tetrachloride, and decomposed
by alkali in carbon tetrachloride-alcohol solution to sodium 0,0-dimethyl
phosphorodithioate, sodium fumarate and alcohol. The sodium 0,0-dimethyl
phosphorodithioate is converted to a cupric salt which is soluble in
carbon tetrachloride with the formation of an intense yellow color. The
color intensity is proportional to the concentration of 0,0-dimethyl
phosphorodithioic acid and is measured photometrically at 418 nm.
(The color is only stable for 5 to 10 min.)
29
-------
PAM Methods - PAM lists three methods for specific residue analysis.
The first two methods have been "tested in varying degrees and are
considered reliable without further validation for the product appli-
cations indicated." The third method has not been "thoroughly tested
through interlaboratory studies."
The First Method - This method refers to the PAM procedure for
organophosphate (PAM, Volume I).
The Second Method - This method is, essentially, the AOAC method
which is described in the preceding section. According to PAM (Volume II),
the AOAC method is generally applicable to "firm fruits and all types of
vegetables." The sensitivity is 0.2 ppm for fruit; 0.5 ppm for vegetables.
Interferences from other pesticides, oxidizable materials and metallic
ions are discussed by Norris et al. (1954)—' and Conroy (1959) .!/
The Third Method - The third method is used for the determination
of malathion residues in fat, liver, meat, eggs and milk in concentrations
down to 1.0, 1.0, '0.5, 0.5, and 0.02 ppm, respectively (freeze-drying
apparatus is required for milk). The method was developed by Norris et
al. (1958)^' and is a modification and adaptation of the procedure of
Norris et al. (1954).
Formulation Analysis Principles-
Three formulation analysis procedures for malathion are described
in AOAC "Methods of Analysis" (1970). Zweig and Sherma'have recom-
mended a gas chromatographic method for the analysis of malathion
formulations. A high pressure liquid chromatographic procedure is used
by the Technical Service, Division, Office of Pesticide Programs of EPA.
I/ Norris, M. V., W. A. Vail, and P. R. Averell, "Colorimetric Estimation
of Malathion Residues," J. Agr. Food Chem., 2:570-573 (1954).
21 Conroy, H. W., "Report on Malathion," J. Assoc. Off. Agr. Chem., 42:
551 (1959).
3/ Norris, M. V., E. W. Easter, L. T. Fuller, and E. J. Kuchar, "Colori-
metric Estimation of Malathion Residues in Animal Products," J. Agr.
Food Chem., 6:111-114 (1958).
30
-------
AOAC Methods - The following formulation analysis methods are presented.
Infrared Spectrophotometric Method (Official Final Action) - This
method is applicable to dusts, dust base concentrates, and wettable
powders where malathion is the only active ingredient. Other extractable
organic materials such as dispersing agents, emulsifiers, and solvents
may interfere and should be tested for interference. Sulfur does not
interfere. The method involves the comparison of infrared spectra (11.0
to 13.0 um) of solutions of unknown and standard malathion in acetonitrile.
Colorimetric Method (Official First Action) - This method is
similar to the previously described AOAC method for specific residue
analysis. Malathion is-decomposed by alkali in alcohol and the sodium
0,0-dimethyl phosphorodithioate is converted to a cupric complex solution
in cyclohexane with formation of an intense yellow compound whose intensity
is proportional to the concentration of 0,0-dimethyl phosphorodithioic
acid and which is measured colorimetrically at 420 nm.
Ferric reagent is added to oxidize materials which would reduce
cupric to cuprous ions. With phosphorodithioic acid, cuprous ions form
a colorless complex which is apparently more stable than the yellow cupric
complex.
The method is applicable to emulsifiable liquids and wettable powders
and dusts, including those containing sulfur. Captan and carbaryl inter-
fere. Before application of this method to mixtures, the affect of un-
familiar components should be specifically determined.
The procedure for this method has recently been updated (1973).—'
Argentimetric Method (Official First Action)^/ - Malathion is cleaved
in alkaline solution to dimethyl phosphorodithioate ion which forms an
insoluble precipitate with silver ion. Malathion concentrations are deter-
mined by potentiometric titration of the hydrolyzed malathion using silver
nitrate.
I/ "Malathion: Colorimetric Method - Official First Action," J. Assoc.
Off. Anal. Chem.. 56(2):461 (1973).
21 "Malathion: Argentimetric Method - Official First Action," J. Assoc.
Off. Anal. Chem., 56(2):460 (1973).
31
-------
Gas Chromatographic Method - According to a method recommended by
Zweig and Sherma, liquid samples or acetonitrile extracts of solid
samples are diluted to appropriate volume with acetonitrile and the
malathion content determined by a gas chromatographic procedure employing
an internal standard technique.
EPA Method - The following formulation analysis method is presented.
High Pressure Liquid Chromatographic Method - The Technical Service
Division of EPA employs a high pressure liquid chromatographic method.
This methodi' is summarized as follows:
1. Equipment - High pressure liquid chromatograph with UV
detector at 254 nm. Operating conditions must be determined
for the individual liquid chromatograph being used to achieve
optimum sensitivity and resolution. Adjustments in attenuation
or amount injected should be made to give convenient size peaks.
2. Preparation of standard - Weigh 0.06 g malathion standard into
a 10 ml volumetric flask and make to volume with methanol.
3. Preparation of sample - For liquids: weigh a portion of sample
equivalent to 0.6 g malathion into a 100 ml volumetric flask
and make to volume with methanol. For dust: weigh a portion
of sample equivalent to 0.6 g malathion into 250 ml Erlenmeyer
flask, add 100 ml methanol, and shake for 1 to 2 hr.
4. Procedure - Using a high pressure liquid syringe, alternately
inject three 5 i\l portions each of standard and sample solutions,
Measure the peak area for each peak and calculate the average
for both standard and sample.
I/ Bontoyan, Warren R., Technical Services Division, Office of Pesti-
cide Programs, Environmental Protection Agency, Personal Communi-
cation (September, 1974).
32
-------
Composition and Formulation
Impurities in Malathion - Technical malathion is a minimum 95% pure.
Among the very minor but controlled maximum impurities are methyl mer-
captan (controlled to 30 ppm maximum to avoid odors) and iron (limited
to 10 ppm maximum to prevent gel formation).
More important are the organophosphate impurities present in mala-
thion. Although the median lethal dosage (LI>5o) °£ technical malathion
to rats orally is 1,000 mg/kg (range 390 to 2,100), the LD50 for these
impurities is much lower. The impurities detected in technical mala-
thion by Pellegrini and Santi (1972)—' (using a thin-layer chromatographic
method) are as follows:
Concentration
of impurities ^50 °^ Pure
Code Name Formula (%) impurity
TES (MeO)2P(S)(SMe) 1 450
OTE (MeO)2P(0) (SMe) 0.1 47
ITE (MeS)2P(0)(OMe) 0.02 96
These compounds greatly increase the toxicity of technical mala-
thion compared to pure malathion.
Pellegrini and Santi (1972) determined an 11*50 of 1,580 mg/kg for
92.2% malathion, but 98% purified malathion had an LD50 of 8,000 mg/kg.
The marked decrease in the 11)50, which is produced by less than 2%
total of these organophosphate impurities, is caused by a potentiation
effect. (When the compounds are mixed, their toxicity effect is syn-
ergistic, not additive.)
Pellegrini and Santi (1972) present data showing this potentiation
effect for each of the impurities separately. In these tests, measured
quantities of each impurity were added to pure malathion (98% purity),
and the 1^)50 was determined at each level. Results are shown in Table 2.
I./ Pellegrini, G., and R. Santi, "Potentiation of Toxicity of Organo-
Phosphorus Compounds Containing Carboxylic Ester Functions Toward
Warm-Blooded Animals by Some Organophosphorus Impurities,"
J. Agr, Food Chem., 20(5)-.944-950 (1972).
33
-------
Table 2. POTENTIATING ACTION OF SOME ORGANOPHOSPRATES ON MALATHION
Percent
Code name impurity Rat oral U^p (mg/kg)
TES 0 8,000
3 5,500
3.5 4,000
4 3,000
ITE 0 8,000
0.02 5,200
0.035 4,450
0.1 2,920
0.2 2,100
0.5 1,240
1.0 605
OTE 0 8,000
0.1 3,900
0.2 2,770
0.3 2,150
Source: Adapted from Pellegrini and Santi, pp. cit- (1972).
A homolog of malathion, the 0,0-dimethyl phosphorodithioate of
ethyl butyl mercaptosuccinate, was found with malathion as a residue
on crops (Gardner et al., 1969i/). This homolog (which contains a
butyl rather than ethyl group on one of the carboxyl groups of the
succinic acid portion of the molecule) is believed to be a contaminant
in the commercial product rather than a chemical degradation product
of malathion. No percentages of contamination are given.
Major Formulations - The major formulations of malathion are dusts (con-
centrated and dilute dusts and wettable powders), liquid formulations
(emulsifiable liquids, a solubilized formulations and oil-based formulations)
If Gardner, A. M., J. N. Damico, E. A. Hansen, E. Lustig, and R. W.
Storherr, "Previously Unreported Homolog of Malathion Found as
Residue on Crops," J. Agr. Food Chem., 17(6):1181-1185 (November-
December 1969).
34
-------
and a variety of other special preparations. A brief description of
representative formulations is presented below (American Cyanamid,
1973,!/ Yost et al., 1955 a and blzl/) .
Dusts and Wettable Powders - Dust concentrates, dilute dusts and wettable
powders represent a major class of malathion formulations. These prep-
arations are widely used in the various insect pest control practices
for which malathion is now registered. Knowledge of the inherent prop-
erties of malathion and the carriers and diluents used is essential for
the production of formulations which have good shelf life expectancy
and satisfactory physical characteristics.
Another important factor in the successful preparation of stable
malathion formulations is the nature of the carrier surface. Surfaces
which tend to be catalytic, i.e., contain metallic ion, metallic oxide
or other surface "hot spots," may contribute to malathion breakdown
during long-term storage. These detrimental effects are especially
pronounced in dilute formulations prepared directly on highly sorptive
clays or where dust concentrates are diluted with them.
Perhaps the most important factor in the stability of malathion
formulations is the temperature encountered during storage. Numerous
powder-type formulations of malathion can be prepared having good
shelf life when stored at 25°C. However, selection of carrier and
diluent becomes very critical at more elevated storage temperatures,
especially in the 37 to 45°C temperature range. Formulations should
be stored in as cool a location as possible. Where relatively high
storage temperature is anticipated, formulation ingredients should be
carefully selected and blends prepared to minimize moisture effects,
acid-base effects and carrier surface influences.
Use of carriers having low moisture content is also essential to
the successful formulation of malathion. Based on present knowledge,
calcined carriers, notably clays, should not be used with malathion if
they have picked up appreciable moisture (more than 2%) during storage
following calcination.
_!/ American Cyanamid, Agricultural Division, Manual for Insecticide
Formulators (1973).
2/ Yost, J. F., J. B. Frederick, and V. Migrdichian, "Some Stability,
Compatibility and Technological Findings on Malathion and Its
Formulations (Part I)," Agr. Chemicals, 10(9):43-45 (September
1955a).
3/ Yost, J. F*., J. B. Frederick, and V. Migrdichian, "Stability, Com-
patibility, Technological Data on Malathion Formulations (Part
II)," Agr. Chemicals, 10(10):42-44, 105-107 (October 1955b).
35
-------
Dust Concentrates - Suggested specific formulas for malathion dust con-
centrates are as follows (American Gyanamid, 1973):
Malathion 25% Dust Concentrates
Formula Type A
Ingredients
Malathion 95% grade
Celite 209 diatomaceous earth
Kaolin clay (acidic condition)
Total
% by weight
27.5 or 27.5
18.0 27.5
54.5 45.0
100.0% 100.0%
Formula Type B
Ingredients
Malathion 95% grade
Celite SSC diatomaceous earth
Pikes Peak 9T66 clay (calcined
condition)
Total
% by weight
27.5 or 27.5
18.0 27.5
54.5 45.0
100.0% 100.0%
Formula Type C
Ingredients
Malathion 95% grade
Kaolin clay (acidic condition)
Pikes Peak 9T66 clay (calcined
condition)
Total
% by weight
27.5
27.5
45.0
100.0%
The effect of carriers on the stability of malathion dust concen-
trated is indicated in Figure 2.
Dilute Dusts - Dilute malathion dust formulations are best prepared by
diluting concentrated dusts with nonsorptive carriers or by direct
impregnation of nonsorptive carriers. Sorptive carriers include such
materials as diatomaceous earth, kaolinite, montmorillonite or volcanic
dust. Nonsorptive carriers include aluminum silicate, calcium carbonate,
calcium sulfate, talc and others.
36
-------
Diatomaceous Earth Carrier
Diatomaceous Earth-Kaolin Carrier
Pikes Peak 9T66
Clay-Diaromaceous
Earth or Kaolin
Carrier
Attapulgite Carrier
Storage Period (Months)
036
/
Source: American Cyanamid (1973)
Figure 4. Effect of carriers on the stability of malathion dust concentrates.
-------
Dilute dusts prepared directly on sorptive carriers deteriorate
rapidly even at 25°C. Thus, the desired procedure is to dilute a dust
concentrate with a nonsorptive diluent. Most extensively investigated
for this purpose have been the pyrophyllite and neutral talc diluents.
Both are excellent choices for use with malathion.
\
Good stability has also been noted^ for most dilute dust prepara-
tions made by direct impregnation on nonsorptive type diluents.
Wettable Powders - The chemical and physical properties of malathion
formulations are similar for both wettable powder and dust concentrates.
Thus, recommended formulas for malathion wettable powders are similar
to those for dust concentrates.
Liquid Formulations - A number of different malathion liquid formula-
tions are now marketed. Liquid formulations include solutions, emulsi-
fiable liquid concentrates, oil-in-water emulsions, oil-based formula-
tions, fly sprays, and formulations suitable for use as spray fogs or
mists.
Liquid formulations of malathion that contain excessive iron may
form a gel. Formulation ingredients should be selected so as not to
produce more than 15 ppm of iron in the finished product. Malathion
contains a maximum 10 ppm of iron when manufactured. The moisture
content of the finished product also should be of a low order of magni-
tude, preferably below 0.570.
Since concentrated malathion liquid formulations have a tendency
to gel if kept in contact with iron, glass-lined or stainless steel
equipment is preferred for preparation of liquid formulations (copper
also is attacked and therefore not suitable).
Suggested proportions of emulsifier, solvent and malathion for
the preparation of 5 Ib/gal (57%) malathion emulsifiable concentrate
are:
Ingredients Percent by weight
Malathion 95% grade 62
Xylene or xylene alternate 30
Emulsifier 8
Total 100
Higher concentrations (for example, 85% malathion) of malathion can be
prepared with more efficient emulsifiers.
38-
-------
Other liquid formulations of malathion include: low-emulsifier
citrus spray concentrates, solubilized malathion formulations, and
oil-based formulations. Oil-b.ased malathion formulations are essen-
tially solutions of malathion in aromatic organic solvents such as
No. 2 fuel oil or deodorized kerosene.
Miscellaneous Formulations - Many other special preparations containing
malathion are now being marketed. These include aerosol formulations,
special formulations for stored-product insect control, granular formu-
lations (for insect control over water surfaces and in areas having
dense foliage), spray and granular bait formulations (for control of
fruit flies and houseflies), formulations for use on freshly painted
surfaces, formulations for pet and human treatment and formulations
for use on masonry surfaces.
Chemical Properties, Reactions and Decomposition Processes
Hydrolysis is the most important decomposition reaction of mala-
thion and has received the most intense investigation. Depending upon
the reaction conditions, hydrolysis can occur via several different
pathways leading to a variety of products. The thermal decomposition
of malathion has also been investigated, but relatively little is known
concerning the decomposition products. Malathion is readily oxidized
to malaoxon, a reaction typical of other sulfur-containing organophos-
phate pesticides. Malathion is degraded by ultraviolet radiation, but
little is known concerning this reaction. The chemical reactions of
malathion are described in the following paragraphs.
Hydrolysis - Malathion has several chemical bonds that are subject to
hydrolysis under environmental conditions (see Reactions (3), (4), and
(5) in Figure 3). Sulfur-carbon cleavage proceeding through an elimina-
tion reaction (3) yields 0,0-dimethyl phosphorodithioic acid and diethyl
fumarate. This is the predominant reaction during alkaline hydrolysis.
Phosphorus-sulfur bond cleavage (Reaction (4)) yields diethyl thiomalate
and 0,0-dimethyl phosphorothionic acid, which would be in equilibrium
with its tautomer, 0,0-dimethyl phosphorothiolic acid. Carboxyl ester
hydrolysis (Reaction (5)) yields a mixture of two products; malathion
a- and malathion p-monoacids.
Spiller (1961)i/ has reported that the stability of malathion in
solution is a function of pH. Malathion was hydrolyzed "instantaneously"
at pH 12.0, whereas at pH 9.0 about 50% was hydrolyzed in 12 hr.
I/ Spiller, D., "A Digest of Available Information on the Insecticide
Malathion," Adv. Pest Control Research, 4:249-335 (1961).
39
-------
S
(CH30)2-P-SH
0,0-Dimethyl
phosphorodithioic
acid
Elimination
Reaction (3)
HCC02Et
Et02CCH
Diethyl fumarate
a
(CH-0)0-P-S-CHC09H
J i. i *•
I
fCH«0) «-P-S-CH-C02Et
It! f*r\ tr*-
n \j\j ~Et L.
Malathion
Malathion
a-monoacid
Carboxyl
Ester
Hydrolysis (5)
> +
(CH30)2-P-S-CHC02Et
HS-CHC02Et
CH2C02Et
Diethyl
thiomalate
Pho sphorus-sulfur
bond cleavage (4)
D
(CH30)2-P'-OH
0,0-Dimethyl
phosphorothionic
acid
Malathion
p-monoacid
0
Equilibrium
(CH00)P-SH
3 2
0,0-Dimethyl
phosphorothiolic
acid
Adapted from Wolfe, N. L., R. 6. Zepp, 6. L. Baughman, and J. A. Gordon, Chemical and Photochemical.
Transformations of Selected Pesticides in Aquatic Systems, EPA, Office of Research and Development
ROAP 21 AIM, Task 09 (Manuscript).
Figure 3. Chemical and photochemical transformations of selected pesticides in aquatic systems.
-------
No hydrolysis could be detected after 12 days in solution of pH 5.0 to
7.0. In a similar study, Konrad et al. (1969)I/ found that after 7
days at pH values of 11.0 and 9.0, 100 and 25%, respectively, of the
malathion was hydrolyzed. At pH values of 2.0, 4.0, and 6.0, no deg-
radation occurred in the same period. Cowart et al. (1971)—' reported
that in a neutral aqueous solution, 59.3% hydrolysis occurred in 1
week.
Ruzicka et al. (1967b)l/ found the half-life of malathion in
ethanol pH 6.0 buffer solution (20:80) at 70°C to be 7.8 hr and re-
ported the hydrolysis kinetics to be pseudo-first-order. In yet an-
other pH study, Weiss and Gakstatter (1964)^t' reported that malathion
is not hydrolyzed at pH below 7.0 over prolonged periods.
Muhlmann and Schrader (1957)JL/ reported that, in alkaline solution,
the primary hydrolysis products of malathion are diethyl fumarate and
0,0-dimethyl phosphorodithioic acid (Figure 3, Reaction (3)). The primary
products in acid solution are dimethyl phosphorothionic acid and di-
ethyl thiomalate (Figure 3, Reaction 4). They also reported that the
rate of hydrolysis increased fourfold with a 10°C increase in tempera-
ture.
Ketelaar and Gersmann (1958)— confirmed the stoichiometry of the
alkaline hydrolysis and determined the relative alkaline hydrolysis
rates and energies of activation for malathion and 18 related compounds.
(These hydrolysis studies were performed at pH 10.03 in 25% aqueous
acetone.)
JL/ Konrad, J. G., G. Chesters, and D. E. Armstrong, "Soil Degradation
of Malathion, a Phosphorodithioate Insecticide," Soil Sci. Soc.
Am. Proc., 33(2):259-262 (March-April 1969).
2/ Cowart, R. P., F. L. Bonner, and E. A. Epps, Jr., "Rate of Hydrolysis
of Seven Organophosphate Pesticides," Bull. Environ. Contain.
Toxicol., 6(3):231-234 (1971).
3_/ Ruzicka, J., J. Thomson, and B. B. Wheals, "The Gas Chromatographic
Determination of Organophosphorus Pesticides. Part II. A Com-
parative Study of Hydrolysis Rates," J. Chromatog., 31:37 (1967b) .
4_/ Weiss, C. M., and J. H. Gakstatter, "The Decay of Anticholinesterase
Activity of Organic Phosphorus Insecticides on Storage in Waters
of a Different pH," Adv. Water Pollution Research, 1:83 (1964).
5_/ Muhlmann, R., and G. Schrader, "Hydrolyse der Insektiziden Phos-
phoraurcester," Z. Naturforsch, 12b:196 (1957).
6/ Ketelaar, J. A. A., H. R. Gersmann, "Chemical Studies on Insecticides,
VI. The Rate of Hydrolysis of Some Phosphorus Acid Esters,"
Recueil des Travaux Chimiques des Pays-Bas (in English), 77:973-
981 (1958).
41
-------
Goldberg et al. (1968)i/ observed that, contrary to expectations,
malathion hydrolyzed slowly on treatment with stoichiometric amounts
of water at ambient temperatures in the pH range of natural water.
Nuclear magnetic resonance measurements showed the half-life for the
hydrolysis process to be greater than 2 weeks.
2 /
Kennedy et al. (1972b)— reported that malathion was not completely
decomposed by 8N sodium hydroxide or 15N ammonium hydroxide (the con-
tact times were not given). These investigators also stated that the
treatment of malathion with triethanolamine produced no reaction.
Based upon other data concerning the alkaline hydrolysis of malathion,
it is surprising that these strongly alkaline reagents were not effec-
tive.
A comprehensive study of malathion hydrolysis was reported
(Wolfe et al., 1974). Acid hydrolysis studies were performed (at
pH 2.59) at elevated temperatures (67 and 87°C) because malathion
is stable in water at this pH (very little decomposition occurred
during 10 days at 27°C). This acid hydrolysis proceeds as indicated
in Figure 5, (Reaction 5), but is much too slow to be significant at
temperatures and pH values common to the aquatic environment (the
half-life is greater than 1 year).
Additional hydrolysis studies were performed at pH 8 and 27°C
(Wolfe et al., 1974). Half-life studies showed the presence of mala-
thion, malathion monoacids, 0,0-dimethyl phosphorodithioic acid, and
diethyl fumarate. The presence of these products demonstrates that
two competing reactions are occurring, carboxyl ester hydrolysis and
0,0-dimethyl phosphorodithioic acid elimination (Figure 3, Reactions 3
and 5). Carboxyl ester hydrolysis is favored at lower temperatures,
as shown by the amount of malathion monoacid present at one half-life;
at 0°C there was 25%; at 27°C, 12%, and at 47°C, 5%.
Liquid chromatographic analysis showed that the monoacid mixture
(27°C) consisted of 857. cv-monoacid and 1570 p-monoacid. The results
indicate that chemical hydrolysis produces different products than
I/ Goldberg, M., H. Babad, D. Groothius, and H. R. Christiansen,
"Nuclear Magnetic Resonance Studies of Phosphorus (V) Pesticides,
III. The Hydrolysis of Aliphatic Pesticides by Aqueous Solutions,"
U.S. Geol. Survey Prof. Paper 600-D. pp. D20-D23 (1968).
2j Kennedy, M. V., B. J. Stojanovic, and F. L. Shuman, Jr., "Analysis
of Decomposition Products of Pesticides," J. Agr. Food Chem., 20(2)
341-343 (March-April 1972b).
42
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does microbial degradation; Paris et al. (1974)i' found that micro-
bial degradation by aquatic organisms gave 99% malathion p-monoacid.
Malathion monoacids are anticipated environmental degradation prod-
ucts and, therefore, their persistence under alkaline reaction conditions
was examined (Wolfe et al., 1974). Assuming no large difference in re-
activity for the two isomers, the monoacids have a half-life of about
24 days at pH 8. These data indicate that malathion monoacids are about
18 times more stable than malathion under the same alkaline (pH 8) condi-
tions. Wolfe et al. (1974) have concluded these monoacids would be more
persistent in the environment.
Konrad et al. (1969) observed that the rates of malathion degrada-
tion in soils were related directly to the extent of malathion adsorp-
tion. This observation suggested that degradation occurred by a chem-
ical mechanism which was catalyzed by adsorption. Malathion degrada-
tion was rapid (50 to 90% in 24 hr, depending on the type of soil) in
both sterile and nonsterile soil systems, and no lag phase occurred
prior to degradation. In aqueous, soil-free systems inoculated with a
soil extract, a lag phase (7 days) occurred, followed by rapid mala-
thion loss, likely due to microbial degradation. Thus, in soils, com-
plete chemical degradation of malathion probably occurs prior to micro-
bial adaptation to malathion.
Thermal Decomposition - Malathion is a reasonably stable compound that
undergoes some decomposition when held much above room temperature.
Heating the purified, nearly colorless liquid for 24 hr at 150°C re-
sulted in the formation of an orange-brown, viscous liquid and some
colorless cloudy material which was immiscible (Metcalf and March,
1953).—' This treatment resulted in the isomerization of approximately
90% of the original material. No decomposition products were identified.
o /
McPherson and Johnson (1956)— examined the variation of decom-
position time with temperature and, for malathion, obtained the follow-
ing results.
I/ Paris, D. F., D. L. Lewis, and N. L. Wolfe, "Rates of Degradation
of Malathion by Bacteria Isolated from an Aquatic System," sub-
mitted for publication (1974).
2j. Metcalf," R. L., and R. B. March, "The Isomerization of Organic Thio-
phosphate Insecticides," J. Econ.Entomol.. 46:288-294 (April 1953).
3_/ McPherson, J. B., Jr., and G. A. Johnson, "Thermal Decomposition of
Some .Phosphorothioate Insecticides," J. Agr. Food Chem., 4(1):
42-49 (January 1956).
43
-------
Temperature (°C) Decomposition time (days)j
115 5
100 20
80 163
65 925
The burning of malathion solutions was investigated by Smith and
Ledbetter (1971).I/ Malathion solutions (1 g/10 ml) in xylene and
kerosene were burned and gases collected above the fire were analyzed.
Samples were collected at various intervals after the ignition of the
solutions. The maximum malathion found from the burning 'malathion-
xylene solutions was 10 u-g/nr at 4.5 min after ignition, and that from
the kerosene mixture was 4 ug/m^ at 2.5 min. Smith and Ledbetter (1971)
noted that these quite low concentrations could result from either a
high efficiency of combustion or a failure of the malathion to evaporate
during the burning.
Some of the decomposition produ'cts of malathion were identified
during the experiments. Diethyl fumarate was separated and positively
identified by infrared spectrophotometry. Some other compounds were
tentatively identified by their retention times in gas chromatography.
Compounds tentatively identified by Smith and Ledbetter (1971) were:
Methanol
Ethanol
Ethyl acetate
Diethyl fumarate
Isomers of dimethyl dithiophosphate
Malathion isomers
Smith and Ledbetter (1971) concluded that several factors tend to
reduce the hazards from organophosphate (e.g., malathion) insecticides
in fires. First, most of the pesticide is destroyed by decomposition
before it can evaporate. Second, over 90% of the evaporating insec-
ticide is destroyed by the flames. Third, the evaporating portion is
considerably diluted by the time it reaches anyone.
21
Differential thermal analysis of malathion (Kennedy et al., 1969)—
provided the following data.
I/ Smith, W. M., Jr., and J. 0. Ledbetter, "Hazards ,from Fires Involving
Organophosphorus Insecticides," Amer. Ind. Hyg. Assoc. J., 32(7):
468-474 (July 1971).
2/. Kennedy, M. V., B. J. Stojanovic, and F. L. Shuman, Jr., "Chemical
and Thermal Methods for Disposal of- Pesticides," Residue Rev.,
29:89-104 (1969).
44
-------
Endothermic peaks- Exothermic peaks-
Product (°C) (°C)
Pure malathion ref-
erence standard 500 250, 308, 333, 422
Commercial product
(5 Ib/gal) 145, 441, 475 261, 308
aj Sensitivity 25%.
According to Melnikov (1971) 3—' malathion, on prolonged heating at
150°C, is isomerized to the corresponding thiolo isomer:
(CH30)2PSCHCOOC2H5
CH2 COOC2H5
At a higher temperature, this reaction proceeds violently and a con-
siderable amount of the product is decomposed, sometimes even explo-
sively.
The thermal decomposition of a commercial malathion formulation
(5 Ib/gal) at various temperatures was investigated by Kennedy et al.
(1969). Extensive decomposition would have been expected at these
high temperatures; thus the contact time, which was not reported,
must have been very short, or the reported loss was equivalent to
total decomposition. The results from this study are summarized as
follows :
Temperature (°C) Percent loss
600 95.3
700 96.0
800 96.3
900 96.4
1000 96.7
I/ Melnikov, N. N., Chemistry of Pesticides, Springer-Verlag, New York,
pp. 357-359 (1971).
/
45
-------
Kennedy et al. (1969) further investigated the thermal decomposi-
tion of malathion (analytical grade). The investigators interpreted
their data to indicate that maximum decomposition of malathion occurs
at 350°C. The observed effects of heating on weight loss, color and
physical appearance were as follows:
Heating time
(min)
30
30
30
30
30
30
30
Temperature
200
250
300
350
400
'500
600
Weight loss
58.7
72.9
76.2
80.
80
80
80.3
Color
Dark-brown
Dark-brown
Dark-brown
Dark-brown
Dark-brown
Dark-brown
Dark-brown
Physical
appearance
Liquid
Liquid, jelly-
like on cooling
Silk flakes
Silk flakes
Silk flakes
Silk flakes
Silk flakes
Additional data on the decomposition of malathion were reported by
Stojanovic et al. (1972). —' In general, the same physical changes pre-
viously reported were observed when malathion was heated. Diethyl
succinate, diethyl malate and diethyl fumarate were tentatively iden-
tified as decomposition products on the basis of infrared spectra.
The following products were identified in the gases obtained from
the burning of analytical grade malathion at 900°CJ carbon monoxide,
carbon dioxide, sulfur dioxide, hydrogen sulfide and oxygen (Kennedy
et al., 1972b). There were four other unidentified products.
I/ Stojanovic, B. J., F. Hutto, M. V. Kennedy, and F. L. Shuman, Jr.,
"Mild Thermal Degradation of Pesticides," J. Environ. Quality,
1(4):397-401 (1972).
46
-------
Oxidation - Malathion is readily oxidized to malaoxon by a variety of
mild oxidizing agents (Wolfe et al., 1974):
(CH30).2-P-S-CH-C02Et > (CH30)2-P-S-CHC02Et
I.
2C02Et CH2C02Et
Malathion Malaoxon
Bromine water, for example, apparently achieves a quantitative conver-
sion of malathion to malaoxon (Ruzicka et al., 1967a— ). Nitric acid
also is reported to effect this conversion (Melnikov, 1971).
Malathion is stable in oxygen-saturated, acidic water for up to
2 weeks (Wolfe et al., 1974). Therefore, oxidation of malathion by
molecular oxygen does not appear to be environmentally significant.
The oxidation of malathion as a result of thermal decomposition
or incineration is discussed in the preceding section.
Ultraviolet Radiation - Ultraviolet radiation decomposes malathion
(Cook and Ottes, 1959, Mitchell, 1961^5.^) . When small quantities of
malathion were placed on filter paper and irradiated by means of a
gennicidal lamp (254 nm), it was converted to compounds which were
less polar than malathion. These compounds were not identified. Mala-
thion photolysis half-life is 990 hr in distilled water (pH 6) with
wavelengths greater than 290 nm. However, in a sample of Suwannee
River water containing a large amount of colored material, malathion
was 507» degraded by sunlight in 16 hr (Wolfe et al., 1974).
I/ Ruzicka, J., J. Thomson, and B. B. Wheals, "The Gas Chromatographic
Examination of Organophosphorus Pesticides and Their Oxidation
Products," J. Chromatog., 3Q(l):92-99 (September 1967a).
2_/ Cook, J. W., and R. Ottes, "Note on the Conversion of Some Organo-
phosphate Pesticides to Less Polar Compounds by Ultraviolet Light,"
J. Assoc. Off. Agr. Chem., 42:211-212 (1959).
3/ Mitchell, L. C., "The Effect of Ultraviolet Light (2537 A) on 141
Pesticide Chemicals by Paper Chromatography," J. Assoc. Off. Agr.
Chem.,.44(4):643+ (1961).
47
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Miscellaneous. Reactions - Malathion, on prolonged contact with iron or
iron-containing material, is reported to decompose and completely lose
insecticidal activity (Melnikov, 1971).
Malathion is decomposed by Raney Nickel, producing diethyl suc-
cinate (70% yield') and an unidentified sulfur-free phosphorus product
(Nagasawa, 197ll/).
Malathion is decomposed within 1 hr by sodium or lithium in liquid
ammonia (Kennedy et al., 1972a2/). No decomposition products were reported,
Occurrence of Malathion Residues in Food and Feed Commodities
The Food and Drug Administration, Department of Health, Education,
and Welfare, monitors pesticide residues in the nation's food supply
through two programs. One program, commonly known as the "total diet
program," involves the examination of food ready to be eaten. This
investigation measures the amount of pesticide found in a high-consumption
varied diet. The samples are collected in retail markets and prepared
for consumption before analysis. The second program involves the ex-
amination of large numbers of samples, obtained when lots are shipped in
interstate commerce, to determine compliance with tolerances. These
analyses are complemented by observation and investigations in the
growing areas to determine the actual practices being followed in the
use of pesticide chemicals.
A majority of the samples collected in these programs are cate-
gorized as "objective" samples. Objective samples are those collected
where there is no suspicion of excessive residues or misuse of the
pesticide chemicals. All samples of imported foods and fish are cate-
gorized as "objective" samples even though there may be reason to be-
lieve excessive residues may be found on successive lots of these food
categories.
Market-basket samples for the total diet studies are purchased
from retail stores, bimonthly, in five regions of the United States.
I/ Nagasawa, K., T. Yamada, and A. Ogamo, "Reductive Cleavage of Sulfur
Containing Organophosphorus Compounds with Raney Nickel," Chem.
Pharm. Bull., 19(11):2373-2379 (November 1971).
2_/ Kennedy, M. V., B. J. Stojanovic, and F. L. Shuman, Jr., "Chemical
and Thermal Aspects of Pesticide Disposal," J. Environ. Quality,
1(1):63-65 (1972a).
48
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A shopping guide totaling 117 foods for all regions is used, but not all
foods are represented in all regions because of differences in regional
dietary patterns. The food items are separated into 12 classes of sim-
ilar foods and prepared for consumption by dietitians in institutional
kitchens. After preparation, the food items are composited into 12
classes of similar foods (e.g., dairy products; meat, fish and poultry;
legume vegetables; and garden fruits) for more reliable analysis and
to minimize the dilution factor. Each class in each sample is a "com-
posite." The food items and the proportion of each used in the study
was developed in cooperation with the Household Economics Research
Division, U.S. Department of Agriculture, and represents the high-
consumption level of a 16- to 19-year old male. Each sample represents
a 2-week supply of food.
Surveillance samples are generally collected at major harvesting
and distribution centers throughout the U.S. and examined in 16 U.S.
Food and Drug Administration district laboratories. Some samples may
be collected in the fields immediately prior to harvest. Surveillance
samples are not obtained in retail markets. Samples of imported food
are collected when offered for entry into the United States.
The results obtained during the 4-year period, fiscal 1965 to 1969,
are compared in Table 3 with the acceptable daily intake (ADI) estab-
lished by the FAO/WHO* Expert Committee (FAO/WHO, 197ol/). The amount
of malathion and total organophosphates calculated from this high-
consumption diet (approximately twice that consumed by a normal in-
dividual) are well below the daily intake regarded as safe by the FAO/WHO
Expert Committee (Duggan et al., 197l!/). However, it should be noted
that malathion accounts for almost all of the total dietary intake of
organophosphates (see Table 3).
Table 4 compares the incidence and daily intake in milligrams of
malathion found in these samples for each of the 4 years.
* Food and Agriculture Organization of the United Nations - World
Health Organization.
I/ FAO/WHO, 1969 Evaluations of Some Pesticide Residues in Food, WHO/
Food Add./70.38 (1970).
2_/ Duggan, R. E., G. Q. Lipscomb, E. L. Cox, R. E. Heatwole, and
R. C. King, "Pesticide Residue Levels in Foods in the United
States from July 1, 1963 to June 30, 1969," Pest. Monit. J.,
5(2):73-212 (September 1971).
49
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Table 3. DIETARY INTAKE OF MALATHION AND TOTAL ORGANOPHOSPRATES
FAO/WHO Mg/kg body weight/day
acceptable total diet studies 4-Year
Compounds daily intake 1965-66 1.966-67 1967-68 1968-69 average
Malathion 0.02 0.0001 0.0002 0.00004 0.0002 0.00013
Total organo-
phosphates — 0.00014 0.00025 0.00007 0.00023 0.00017
Adapted from Duggan et al., op. cit. (1971).
Table 4. AVERAGE INCIDENT AND DAILY INTAKE OF MALATHION
1965-66 1966-67 1967-68 1968-69
Percent Daily Percent Daily Percent Daily Percent Daily
positive intake positive intake positive intake positive intake
composites^/ (mg) composites—' (ing) composites (mg) composites (mg)
5.3 0.009 3.6 0.010 1.9 0..003 5.8 0.012
a/ 312 Composites examined.
b_/ 360 Composites examined.
Adapted from Duggan et al., op. cit. (1971).
50
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The results of the FDA analytical studies are tabulated for the
following food classes:
Dairy Products Poultry
Large Fruits Eggs
Small Fruits Fish
Grains and Cereals (Human) Shellfish
Leaf and Stem Vegetables Grains (Animal)
Vine and Ear Vegetables Infant and Junior Foods
Root Vegetables Tree Nuts
Beans Vegetable Oil Products
Red Meat
Summaries have been prepared (Duggan et al., 1971) for each of
the above food classes from data obtained from samples shipped in
interstate commerce and from samples imported into the United States
during fiscal 1964-1969. Malathion was detected in only two of these
food classes (grain and cereals for human use, and grains for animal
consumption). These residue data are presented in Tables 5 and 6.
The most recently available analytical data are presented in
Table 7 which lists the incidence and ranges of levels for malathion
detected in grains and cereal for human use and grains for human con-
sumption. No significant malathion residues were detected in the
other food classes. These data cover the years 1964-1969. Limited
data are available for the year 1970 (Corneliussen, 1972.1/), and a
complete update on pesticide residue data is expected in the forth-
coming September 1974 issue of the Pesticide Monitoring Journal.
Duggan et al. have concluded that, in grains and cereals for
human use, malathion residues are increasing in incidence and in
concentration.
Acceptable Daily Intake
The acceptable daily intake (ADI) is defined as the daily intake
which, during an entire life-time, appears to be without appreciable
risk on the basis of all known facts at the time of evaluation (Lu,
19732/) . It is expressed in milligrams of the chemical per kilogram of
body weight (mg/kg).
If Corneliussen, P. E., "Residues in Foodiand Feed: Pesticide Residues
in Total Diet Samples (VI)," Pest. Monit. J., 5(4):313-329 (March
1972).
2/ Lu, F. C., "Toxicological Evaluation of Food Additives and Pesticide
Residues and Their 'Acceptible Daily Intakes1 for Man: The Role of
WHO, in Conjunction with FAO," Residue Rev.. 45:81-93 (1973).
51
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Table 5. MALATHION RESIDUES IN CEREALS
AND GRAINS FOR HUMAN USE
(Fiscal Years 1964-1969)
Raw agricultural Number of samples Incidence Average
products5./ examined (%) (ppm)
Domestic 8,005 22.1-/ 0.56
Imported 104
Total diet samples— 134 28.4 0.012
ready-to-eat foodH/ (composites)
a/ Wheat, grain, corn, rice, etc.
b_/ Grain and cereal composites: flour, bread, cornmeal, vegetable
corn, rice, macaroni, pie crust, etc.
£/ Not included in analytical method, fiscal 1964 to 1965.
Adapted from Duggan et al., op. cit. (1971).
Table 6. MALATHION RESIDUES IN RAW DOMESTIC GRAIN
PRODUCTS FOR ANIMAL CONSUMPTION
(Fiscal Years 1966-1969)
Raw Agricultural Products: Wheat, Grain Corn, Milo
Domestic
Incidence Average
(%) (ppm) Domestic
18.3-' 0.12 Number of samples examined- 1,168
Percent with residues 40.6
a/ Not included in analytical method, fiscal 1964 to 1969,
Adapted from Duggan et al., op. cit. (1971).
52
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Table 7. DISTRIBUTION OF MALATHION RESIDUES IN GRAINS
AND CEREAL BY QUANTITATIVE RANGES (ppm)
Grains and Cereal
for Human Use
Percent distribution of samples
Domestic
Range ppm
No. samples
None found
< 0.00 - < 0.03
0.04-0.10
0.11-0.50
0.51-1.00
1.01-1.50
1.51-2.00
Above 2.00
No. samples
None found
< 0.00 - < 0.03
0.04-0.10
0.11-0.50
0.51-1.00
1.01-1.50
1.51-2.00
Above 2.00
1964-1967
2,107
89.93
4.41
0.99
2.37
0.80
0.37
--
1.09
710
90.28
2.25
1.54
4.08
0.70
0.14
0.14
0.84
1968
359
38.72
22.01
10.31
14.76
5.01
1.95
1.67
5.57
Grains
119
40.34
18.49
14.29
18.49
5.88
0.84
0.84
0.84
1969
234
29.49
27.35
10.26
16.24
5.56
3.85
2.56
4.70
for Animal
19
21.05
36.84
5.26
10.53
--
—
10.53
15.79
Imported
Total 1964-1967 1968 1969 Total
2,700 20 — — 20
77.89 100.00 -- -- 100.00
8.74
3.04
5.22
1.78
0.89
0.44
2.00
Consumption
848 45 1 46
81.72 100.00 -- — 97.83
5.31 -- 100.00 — 2.17
3.42
6.25
1.42
0.24
0.47
1.18
Data from Duggan et al., op. cit. (1971).
53
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For malathion the ADI is 0.02 mg/kg. This level was set at the
1966 Joint Meeting of the FAO Committee on Pesticides in Agriculture
and the WHO Expert Committee on Pesticide Residues (FAO/WHO, 1967ai/).
A joint meeting is held annually and new evidence is considered which
would warrant a change in the ADI of any pesticide. The level for
malathion has not been changed through 1971 (FAO/WHO, 1972^7).
In making the evaluation, all available research on malathion
concerning its biochemical effects, toxicology, and teratology is
considered.
Tolerances
U.S. Tolerances - Section 408 of the Food, Drug and Cosmetic Act, as
amended., gives procedures for establishing tolerances for pesticide
chemicals on raw agricultural commodities. Section 409 applies to
food additives, including pesticide chemicals on processed foods.
Tolerances are published in the Code of Federal Regulations, Title 40,
and in the Federal Register. A summary of current U.S. tolerances
for malathion on raw agricultural commodities is presented in Table 8.
According to Lu (1973), U.S. tolerances which are established should
not result in the maximum ADI being reached each day. He gives the following
reasons:
1. The tolerance reflects the maximum level of residue
resulting from good agricultural practice, but this
level is often not reached.
2. The tolerance is based on the assumption that the
particular pesticide is used on all food in the class
in question, and this is rarely the case.
3. Much of the residue will be lost in storage, proces-
sing and cooking.
The tolerances are also based upon the entire product as purchased in
the market. However, the product, as purchased, may not be entirely
consumed.
I/ FAO/WHO, Evaluation of Some Pesticide Residues in Food. WHO/Food
Add./67.32 (1967a).
21 FAO/WHO, "Pesticide Residues in Food," Report of the 1971 Joint
FAO/WHO Meeting on Pesticide Residues, World Health Organization
Tech. Rept. Series No. 502 (1972).
54
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Table 8. V.S. TOLERANCES FOR HALATHIOH OK RAW AGRICULTURAL COMMODITIES
01
ppa Crop PPBI
135 Alfalfa 6
8 Almonds 8
50 Almond hull* 8
8 Anise 135
8 Apples 135
8 Apricots 8
8 Asparagus 1
8 , Avocados 8
8 Barley 4
8 Beans
8 Beets (Including tops)
8 Blackberries 8
8 Blackcyc pe*s 8
8 Blueberries 8
8 Boysenbcrrles 8
8 Broccoli 8
8 Brussels sprouts 6
8 Cabbage 135
8 Carrots 8
4 Cattle, beef - meat, fat, meat by-products 8
(not to be exceeded in any cut of meat or 8
neat by-products) 8
O.S Cattle, dairy - in milk fat 135
8 Cauliflower 8
8 ' Celery 1
8 Cherries 8
1 Chestnuts 8
135 Clover 0.5
8 Collards O.S
8 Corn forage
8 Corn grain 8
2 Corn (kernels plus cob with husk removed) 8
2 Cottonseed 8
8 Covpcas 8
135 Covpea (hay and forage) 8
8 Cranberries 8
8 Cucumbers 8
8 Currants 1
8 D.indellons 8
8 Dates 8
8 Dewberries 8
0.1 £f',es (from application to poultry) 8
8 F.Rg plants 135
8 Endive (escarole) 8
8 Figs 8
1 Filberts 8
8 Garlic 8
4 Coats - meat, fat, meat by-products 8
(not to be exceeded in any cut of meat 8
or meat by-products) 8
Crop ppm
Gooseberriea 8
Grapefruit 8
Grapes 8
Grass 8
Grass hay 4
Guavas
Hops
Horseradish 8
Horses - meat, fat, meat by-products 8
(not to be exceeded in any cut of 8
meat or meat by-products) 8
Kale 8
Kohlrabi B
Kunquats • 8
Leeks 8
Lemons 0.6
Lentils 0.2
Lespedeza (hay and straw) 8
Lespcdeza seed 8
Lettuce 4
Limes 0.2
Loganberries
Lupine (hay and straw) 8
Lupine seed 8
Macedonia nuts 8
Mangoes 135
Melons 8
Milk (from applications to dairy cows) 8
Milk fat (from applications to dairy 8
cows) 8
Mushrooms 1
Mustard greens 8
Nectarines 1
Oat 4
Okra
Onions (including green onions)
Oranges 8
Papayas 8
Parsley 8
Parsnips 8
Passion fruit 8
Peaches 135
Peanut (hay and forage) 8
Peanuts' 8
pears 8
Peas 8
Pcavlncs
Peavine hay
Pecans
Peppermint
Crop
Peppers
Pineapples
Plums
Potatoes
Poultry - meat, fat, meat by-products
(not to be exceeded In any cut of meat or
meat by-products)
Prunes
Pumpkins
Quinces
Radishes
Raspberries
Rice
Rutabagas
Rye
Safflower oil
Safflower seed
Salsify (including tops)
Shallots
Sheep - fat, meat, meat by-products
(not to be exceeded la any cut of meat or
meat by-products)
Sorghum forage
Sorghum grain
Soybeans (dry and succulent)
Soybean (forage and hay)
Spearmint
Spinach
Squash (summer and winter)
Strawberries
Sugar beet roots
Sugar beet tops
Sweet potatoes
Swine - meat, fat, meat by-products
(not to be exceeded in any cut of meat or
meat by-products)
Swiss chard
Tangelos
Tangerines
Tomatoes
Turnips (including tops)
Vetch (hay and straw)
Vetch seed
Walnuts
Watercress
Wheat
Source: El'A Conpendtum of Registered Pesticides, Vol. Ill, U.S. Environmental Protection Agency (1973),
-------
International Tolerances - Tolerances established by individual nations may
be based on recommendations of the FAO/WHO Expert Committee on Food Additives.
The Committee evaluates all residue data submitted by interested parties and
uses the following criteria (FAO/WHO, 1962,i/ for making tolerance
recommendations:
1. Decide upon the effective level of the food additive under
consideration that would be needed in good technological
practice.
2. Examine the possible uses and list all the foods in which
the food additive might be used.
3. Calculate the daily intake level that might occur if the
food additive was used in all the foods for which it might
be a useful additive, working on the basis of the average
intake of the food materials containing the additive. This
average intake for appropriate population groups is obtained
from national food consumption surveys.
4. Obtain the necessary information from which to calculate the
average body weight of the population group concerned (usually
between 50 to 70 kg).
5. From this information, calculate the intake of the additive
in milligrams per kilograms of body weight per day.
6. Check the figure against the acceptable intakes given for the
substances in the table. If it falls within the unconditional
intake zone, the situation is satisfactory and the level
proposed may be accepted. If it falls within the conditional
intake zone, further scientific advice is required before the
level of use proposed is accepted.
I/ FAO/WHO, Food and Agricultural Organization of the United Nations/
World Health Organization, "Evaluation of the Toxicity of a Number
of Antimicrobials and Antioxidants," Sixth Report, Joint FAO/WHO
Expert Committee on Food Additives, World Health Organization Tech.
Kept. Series No. 228. Geneva (1962).
56
-------
The validity of the above criteria was reaffirmed at the 1966
FAO/WHO meeting (FAO/WHO, 1967b!/).
Table 9. MALATHION TOLERANCES ESTABLISHED BY FAO/WHO
ppm
Raw cereals, nuts, dried fruits 8
Whole meal and flour from rye and wheat 2
Citrus fruit 4
Blackberries, raspberries, lettuce, endive, cabbage, spinach . . 8
•Cherries, peaches, plums 6
Broccoli 5
Tomatoes, kale, turnips 3
Beans (green), apples 2
Strawberries, celery 1
Fears, blueberries, peas (in pods), cauliflower, peppers,
eggplant, kohlrabi, roots (except turnips), Swiss chard,
collards 0.5
Adapted from FAO/WHO, op. cit. (1972).
I/ FAO/WHO, "Specifications for the Identify and Purity of Food Addi-
tives and Their Toxicological Evaluation: Some Emulsifiers and
Stabilizers and Certain Other Substances," 10th Report, Joint
FAO/WHO Expert Committee on Food Additives, World Health Organi-
zation Tech. Rept. Series No. 373 (1967b).
57
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References
American Cyanamid, Agricultural Division, Manual for Insecticide Formu-
lators (1973).
Association of Official Analytical Chemists, Official Methods of Analysis
of the Association of Official Analytical Chemists, llth ed.,
Washington, D.C. (1970).
Backlund, G. R., J. F. Martino, and R. D. Divine (to American Cyanamid
Company), U.S. Patent No. 3,463,841 (25 August 1969).
Bontoyan, Warren R., Technical Services Division, Office of Pesticide
Programs, Environmental Protection Agency, Personal Communication
(September 1974).
Cassaday, J. T. (to American Cyanamid Company), U.S. Patent No. 2,278,652
(18 December 1951).
Conroy, H. W., "Report on Malathion," J. Assoc. Off. Agr. Chem.. 42:551 (1959),
Cook, J. W., and R. Ottes, "Note on the Conversion of Some Organophosphate
Pesticides to Less Polar Compounds by Ultraviolet Light," J. Assoc. Off.
Agr. Chem., 42:211-212 (1959).
Corneliussen, P. E., "Residues in Food and Feed: Pesticide Residues in
Total Diet Samples (VI)," Pest. Monit. J., 5(4):313-329 (March 1972).
Cowart, R. P., F. L. Bonner, and E. A. Epps, Jr., "Rate of Hydrolysis
of Seven Organophosphate Pesticides," Bull. Environ. Contain. Toxicol.,
6(3):231-234 (1971).
Cyanamid International, Malathion Insecticide for Adult Mosquito Control
(Bulletin), Wayne, New Jersey.
Duggan, R. E., 6. Q. Lipscomb, E. L. Cox, R. E. Heatwole, and R. C. King,
"Pesticide Residue Levels in Foods in the United States from July 1,
1963, to June 30, 1969," Pest. Monit. J., 5(2):73-212 (September 1971).
FAO/WHO, "Evaluation of the Toxicity of a Number of Antimicrobials and
Antioxidants," Sixth Report, Joint FAO/WHO Expert Committee on Food
Additives, World Health Organization Tech. Rept. Series No. 228 (1962).
FAO/WHO, Evaluation of Some Pesticide Residues in Food, WHO/Food Add./
67.32 (1967a).
FAO/WHO, "Specifications for the Identity and Purity of Food Additives and
Their Toxicological Evaluation: Some Emulsifiers and Stabilizers and
Certain Other Substances/1 10th Report, Joint FAO/WHO Expert Committee on
Food Additives, World Health Organization Tech. Rept. Series No. 373 (1967b),
FAO/WHO, 1969 Evaluations of Some Pesticide Residues in Food, WHO/Food
Add./70.38 (1970).
58
-------
FAO/WHO, "Pesticide Residues in Food," Report of the 1971 Joint FAO/WHO
Meeting on Pesticide Residues, World Health Organization Tech. Rept.
Series No. 502 (1972).
Gardner, A. M., J. N. Damico, E. A. Hansen, E. Lustig, and R. W. Storherr,
"Previously Unreported Homolog of Malathion Found as Residue on Crops,"
J. Agr. Food Chem.. 17(6):1181-1185 (November-December 1969).
Goldberg, M., H. Babad, D. Groothius, and H. R. Christiansen, "Nuclear
Magnetic Resonance Studies of Phosphorus (V) Pesticides. III. The
Hydrolysis of Aliphatic Pesticides by Aqueous Solutions," U.S. Geol.
Survey Prof. Paper 600-D. pp. D20-23 (1968).
Kennedy, M. V., B. J. Stojanovic, and F. L. Shuman, Jr., "Chemical and
Thermal Methods for Disposal of Pesticides," Residue Rev.. 29:89-104
(1969).
Kennedy, M. V., B. J. Stojanovic, and F. L. Shuman, Jr., "Chemical and
Thermal Aspects of Pesticide Disposal," J. Environ. Quality, 1(1):
63-65 (1972a).
Kennedy, M. V., B. J. Stojanovic, and F. L. Shuman, Jr., "Analysis of
Decomposition Products of Pesticides," J. Agr. Food Chem., 20(2):341-
343 (March-April 1972b).
Ketelaar, J. A. A., H. R. Gersmann, "Chemical Studies on Insecticides.
VI. The Rate of Hydrolysis of Some Phosphorus Acid Esters," Recueil
des Travaux Chimiques des Pays-Bas (in English), 77:973-981 (1958).
Konrad, J. G., G. Chesters, and D. E. Armstrong, "Soil Degradation of
Malathion, a Phosphorodithioate Insecticide," Soil Sci. Soc. Amer.
Proc., 33(2):259-262 (March-April 1969).
Lawless, E. W., and T. L. Ferguson of Midwest Research Institute, and
R. von Rumker of RvR Consultants, The Pollution Potential in Pesticide
Manufacturing» for the Environmental Protection Agency, Contract No.
68-01-0142 (January 1972).
Lu, F. C., "Toxicological Evaluation of Food Additives and Pesticide
Residues and Their 'Acceptable Daily Intakes' for Man: The Role of
WHO, in Conjunction with FAO," Residue Rev., 45:81-93 (1973).
McPherson, J. B., Jr., and G. A. Johnson, "Thermal Decomposition of Some
Phosphorothioate Insecticides," J. Agr. Food Chem., 4(1):42-49 (January
1956).
"Malathion: Argentimetric Method - Official First Action," J. Assoc. Off.
Anal. Chem.. 56(2):460 (1973).
"Malathion: Colorimetric Method - Official First Action," J. Assoc. Off.
Anal. Chem.. 56(2):461 (1973).
59
-------
Melnikov, N. N., Chemistry of Pesticides. Springer-Verlag, New York,
pp. 357-359 (1971).
Metcalf, R. L., and R. B. March, "The Isomerization of Organic Thiophos-
phate Insecticides," J. Econ. Entomol., 46:288-294 (April 1953).
Mitchell, L. C., "The Effect of Ultraviolet Light (2537 A) on 141 Pesti-
cide Chemicals by Paper Chromatography," J. Assoc. Offic. Agr. Chem.,
44(4):643+ (1961).
i
Muhlmann, R., and G. Schrader, "Hydrolyse der Insektiziden Phosphoraur-
cester," Z. Naturforsch. 12b:196 (1957).
Nagasawa, R., T. Yamada, and A. Ogamo, "Reductive Cleavage of Sulfur
Containing Organophosphorus Compounds with Raney Nickel," Chem. Pharm.
Bull., 19(11):2373-2379 (November 1971).
Norris, M. V., E. W. Easter, L. T. Fuller, and E. J. Kuchar, "Colori-;
metric Estimation of Malathion Residues in Animal Products," J. Agr.
Food Chem.. 6:111-114 (1958).
Norris, M. V., W. A. Vail, and P. R. Averell, "Colorimetric Estimation
of Malathion Residues," J. Agr. Food Chem.. 2:570-573 (1954).
Paris, D. F., D. L. Lewis, and N. L. Wolfe, "Rates of Degradation of
Malathion by Bacteria Isolated from an Aquatic System," submitted for
publication (1974).
Pellegrini, G., and R. Santi, "Potentiation of Toxicity of Organophos-
phorus Compounds Containing Carboxylic Ester Functions Toward Warm-
Blooded Animals by Some Organophosphorus Impurities," J. Agr. Food.
Chem., 20(5):944-950 (1972).
Ruzicka, J., J. Thomson, and B. B. Wheals, "The Gas Chromatographic
Examination of Organophosphorus Pesticides and Their Oxidation Products,1
J. Chromatog.. 30(l):92-99 (September 1967a).
Ruzicka, J., J. Thomson, and B. B. Wheals, "The Gas Chromatographic
Determination of Organophosphorus Pesticides. Part II. A comparative
Study of Hydrolysis Rates," J. Chromatog., 31:37 (1967b).
Smith, W. M., Jr., and J. 0. Ledbetter, "Hazards from Fires Involving
Organophosphorus Insecticides," Amer. Ind. Hyg. Assoc. J., 32(7):
468-474 (July 1971).
Spiller, D., "A Digest of Available Information on the Insecticide
Malathion." Adv. Pest Control Research. 4:249-335 (1961).
Stojanovic, B. J., F. Hutto, M. V. Kennedy, and F. L. Shuman, Jr., "Mild
Thermal Degradation of Pesticides," J. Environ. Quality. 1(4):397-401
(1972).
60
-------
U.S. Environmental Protection Agency, EPA Compendium of Registered
Pesticides; Insecticides, Araricides. Molluscides and Anti-Fouling
Compounds. Vol. Ill (1973).
U.S. Department of Health, Education and Welfare, Food and Drug Administration,
Pesticide Analytical Manual. 2 vols. (1971).
Weiss, C. M., and J. H. Gakstatter, "The Decay of Anticholinesterase
Activity of Organic Phosphorus Insecticides on Storage in Waters of
a Different pH," Adv. Water Pollution Research, 1:83 (1964).
Wolfe, N. L., R. G. Zepp, G. L. Baughman, and J. A. Gordon, "Kinetic
Investigation of Malathion Degradation in Water," EPA ORD Prog.
Element 1BA023 ROAP 21 AIM, Task 09 (1974).
Yost, J. F., J. B. Frederick, and V. Migrdichian, "Some Stability,
Compatibility and Technological Findings on Malathion and Its Formula-
tions (Part I)," Agr. Chemicals, 10(9):43-45 (September 1955a).
Yost, J. F., J. B. Frederick, and V. Migrdichian, "Stability, Compatibility,
Technological Data on Malathion Formulations (Part II), Agr. Chem.,
10(10):42-44, 105-107 (October 1955b).
Zweig, G., and J. Sherma, Analytical Methods for Pesticides and Plant
Growth Regulators, Vol. VI: Gas Chromatographic Analysis, Academic
Press, New York (1972).
61
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SUBPART II. B. PHARMACOLOGY AND TOXICOLOGY
CONTENTS
Acute, Subacute and Chronic Toxicity . 65
Toxicity to Laboratory Animals 65
Acute Oral Toxicity - Rats 65
Acute Toxicity Routes Other Than Oral - Rats 67
Subacute Oral and Intraperitoneal Toxicity - Rats 70
Subacute Inhalation Toxicity - Rats . 70
Chronic Oral Toxicity - Rats 71
Acute Oral Toxicity - Mice 73
Acute Toxicity Routes Other Than Oral - Mice 73
Subacute Oral and Inhalation Toxicity - Mice 74
Acute Oral, Intraperitoneal and Dermal Toxicity - Guinea
Pigs 74
Subacute and Chronic Toxicity - Guinea Pigs 75
Subacute, Dermal, and Inhalation Toxicity - Guinea Pigs 75
Acute and Chronic Oral Toxicity - Chickens 76
Subacute Oral and Dermal Toxicity - Chickens 76
Acute, Subacute and Chronic Toxicity - Dogs 76
Acute, Subacute and Chronic Toxicity - Cats 77
Acute, Subacute and Chronic Toxicity - Rabbits 77
Toxicity to Domestic Animals 77
Goats 77
Sheep 77
Cattle 78
Symptomology and Pathology Associated with Mammals 78
Summary 79
Metabolism of Malathion 80
Absorption 80
Distribution 81
Excretion 82
Bio transformation 82
62
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CONTENTS (Continued)
Activation 82
Degradation 83
Potentiation 85
Miscellaneous Reactions 87
Tissue Accumulation 87
Summary 88
Effects on Reproduction 88
Laboratory Animals 88
Avian Species 89
Domestic Animals 90
Teratogenic Effects 91
Mammals 91
Avian - Embryotoxicity 91
Mollusca 94
Behavioral Effects 95
Toxicity Studies with Tissue Cultures . . 96
Mutagenic Effects '. 98
Oncogenic Effects 98
Effects on Humans 98
Acute Toxicity 98
Symptoms of Malathion Poisoning 101
Dermal Effects 102
Inhalation Effects 105
Occupational Exposure Hazards 105
Spraying Operations 105
Accidents 110
Summary 110
Effects on Reproduction 110
Teratogenic Effects Ill
Behavioral Effects Ill
Toxicity Studies with Tissue Cultures Ill
Mutagenic and Oncogenic Effects Ill
63
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CONTENTS (Continued)
Effects on Humans 112
Symptoms of Malathion Poisoning 112
Dermal Effects l 112
Inhalation Effects 113
Occupational Exposure Hazards 113
References 114
64
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This section is concerned with information on the acute, subacute
and chronic toxicities of malathion; a brief review is also given of
the characteristic symptoms and pathology. The metabolism of malathion
is discussed as related to its absorption, distribution, excretion,
biotransformation, and tissue accumulation. Other subjects that have
been reviewed are the effects of malathion on reproduction, malformation
of the young, behavioral effects, and the toxic effects of this pesticide
to tissue cultures. There were no studies found on the ability of
malathion to produce mutagenesis and/or oncogenic effects in laboratory
animals. The hazards posed by the exposure of humans to malathion have
been reviewed in relation to acute and subacute toxicity, the symptoms
associated with malathion poisoning, the routes of exposure (mainly
dermal and respiratory), and the hazards associated with the use of
malathion in field operations. The section summarizes rather than
interprets scientific data reviewed.
Additional data on the acute toxicity of malathion can be found
under the subsection on Analytical Methods, p. 23.
Acute, Subacute and Chronic Toxicity
The information in this subsection is related to the toxicological
studies of laboratory and domestic animals.
Toxicity to Laboratory Animals
Acute oral toxicity - rats - The results of a number of tests for
the acute oral toxicity of malathion to rats are shown in Table 10.
The vehicle and formulation have a considerable influence on absorption
following oral administration. Early samples of the technical material
were 65 to 77% pure, while later materials approximated 90 to 99%. The
acute oral toxicity of malathion to mammals appeared to vary inversely
with the degree of purity of the compound (Hazelton and Holland, 1953^').
In one study, when rats were exposed to the compound, males were more
susceptible to malathion than females (Hazleton and Holland, 1953).
However, this difference in susceptibility between the sexes was not
shown in another study (Gaines, 1969^7). Gaines states that the majority
of pesticides tested by the oral route were more toxic to female than
I/ Hazleton, L. W., and E. G. Holland, "Toxicity of Malathion: Summary
of Mammalian Investigations," AMA Arch. Ind. Hyg. Occup. Med.,
8:399-405 (1953).
27 Gaines, T. B., "Acute Toxicity of Pesticides," Toxicol. Appl.
Pharmacol., 14:515-534 (1969).
65
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Table 10. ACUTE ORAL TOXICITY OF MALATHION TO RATS
Dose (mg/kg)
Formulation Measurement Male Female References
Technical 99% Oral LD50 1,845*/ £/
Technical 98% Oral LD5Q 1,400£/ £/
Technical 90% Oral LD5Q 480£/ f/
Technical 99% Oral LD50 l,500k/ h/
Technical 90% Oral LD50 390k/ h/
Technical 90% Oral LD50 1,156£/ f/
Technical 90% Oral LD50 940£/ h/
Technical 65% Oral LD5Q 3,690£/ 739-^ f/
Technical 95% Oral LD5Q 2,1001' h/
Technical 99% • Oral LD5Q 1,375£/ l.OOOl/ i/, i/, k/
Lowest dose to kill an adult rat
Technical 90%+ Oral l,000l/ 7501/ i/
a/ Dissolved in corn oil.
b/ Dissolved in vegetable oil.
c/ Dissolved in propylene glycol.
d/ Undiluted.
e_/ Dissolved in peanut oil.
f/ Hazelton and Holland, op. cit. (1953).
£/ Frawley, J. P., H. N. Fuyat, E. C. Hagan, J. R. Blake, and 0. G.
Fitzhugh, "Marked Potentiation in Mammalian Toxicity from
Simultaneous Administration of Two Anticholinesterase Compounds,"
J. Pharmacol. Exp. Ther.. 121:96-106 (1957).
h/ Golz, H. H., and C. B. Shaffer, Malathion; Summary of Pharmacology
and Toxicology, American Cyanamid Company, New York, 2-14 (1956
Revised).
if Kimmerle, G., and D. Lorke, "Toxicology of Insecticidal Organo-
phosphates," Pflanz.-Nachr. Bayer, 21:111-142 (1968).
j/ Gaines, T. B., OJJL. £i£.. (1969).
k/ "Toxic Hazards of Pesticides to Man," World Health Organization,
Tech. Rept. Ser. No. 114 (1956).
66
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male rats. The reason for these reported differences are not clear.
Young animals appear to be more susceptible to malathion than older
animals (Brodeur and DuBois, 1963—'). The dietary protein concentra-
tion also influences the acute oral toxicity of malathion. It was
shown that as the amount of casein in the diet of rats is decreased,
the acute toxicity is increased (Boyd, 1969—'). Thus, much of the
variation in acute LDrn values can be attributed to differences in
experimental techniques.
The toxicity of malathion may be affected by other organophosphate
compounds. Frawley et al. (1957) observed that the simultaneous admin-
istration of two organophosphate compounds produced a higher toxic
effect in some instances than was to be expected, based on the known
toxicity of each compound. This was a potentiation effect, and the
toxicity of malathion has been shown to be influenced by other, but
not all, organophosphate compounds (Kimmerle and Lorke, 1968).
Acute toxicity routes other than oral - rats - The toxicity of
malathion for rats by routes of exposure other than oral is shown in
Table 11.
The intraperitoneal toxicity of malathion varied with the age of
the animals. The U^Q for adult rats was 750 and the 1^50 for weanling
rats was 340 mg/kg (Brodeur and DuBois, 1963).
Although exposure by the intraperitoneal route is of less impor-
tance than by some other route in characterizing the potential health
hazard of the compound, it is important in giving information as to
the inherent toxicity of the compound. The intravenous administration
of malathion to rats represented the most toxic route and the sub-
cutaneous toxicity was comparable to that of the oral. The acute
intravenous and subcutaneous U>5Q values are 50 mg/kg and 1,000 mg/kg,
respectively. The dermal LD^Q value of malathion is 4,444 mg/kg.
Exposure of rats to saturated vapors of the compound caused no mor-
tality and the only symptoms noted were labored breathing and depres-
sion (Spiller, 196ll/).
I/ Brodeur, J., and K. P. DuBois, "Comparison of Acute Toxicity of
Anticholinesterase Insecticides to Weanling and Adult Male Rats,"
Proc. Soc. EXP. Med.. 114(2):509-511 (1963).
2/ Boyd, E. M., "Dietary Protein and Pesticides Toxicity in Male
Weanling Rats," Bull. WHO, 40:801-805 (1969).
3/ Spiller, D., "A Digest of Available Information on the Insecticide
Malathion," Adv. Pest Control Res., Vol. IV, Interscience
Publishers (1961).
67
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Table 11. ACUTE TOXICITY OF MALATHION FOR RATS VIA
ROUTES OTHER THAN ORAL
Measurement
IP LD50
(mg/kg)
IVLD50
(mg/kg)
SC ID,
50
(mg/kg)
DLD5Q
(mg/kg)
LC50 - 1 hr
(mg/jfc)
Dose
Adults
Male
750
50
1,000
> 4,444
>60
Female
Weanlings
Male
340
50
> 4,444
> 60
References
a.b/
£/
!/
e,£7
a/ Kimmerle and Lorke, op. cit. (1968).
b_/ Brodeur and DuBois, op. cit. (1963).
c/ Hagan, E. C., "Acute Toxicity of 0,0-Dimethyl Dithiophosphate of
Diethyl Mercaptosuccinate," Pharmaeol. Exp. Ther., 12:327 (1953)
d/ Spiller, O£. cit. (1961).
ej Gaines, op. cit. (1969).
f/ Anon., WHO, cp.. ulL. (1956).
g_/ Hazleton and Holland, op. cit. (1953).
Note: IP LDijQ - Intraperitoneal exposure.
- Intravenous exposure.
IVLD50
SC LD5Q - Subcutaneous exposure.
D
LC5Q
- Dermal exposure.
- Lethal concentration by inhalation.
68
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Table 12. SUBACUTE ORAL TOXICITY TEST IN RATS FED MALATHION
Concentration of
malathion in feed Duration Mortality
(ppm) of test (%)
100, 1,000,
5,000
100, 500
4,000
1,000
33 days
8 weeks
6 months
0
5 months 0
0
References
Comments
No effects on food in- a/
take and weight gain
at any level. Cho-
linesterase activity
of erythrocytes at
100 ppm not depressed,
but significantly de-
pressed at 1,000 and
5,000 ppm.
No effects on whole b/
blood cholinesterase
activity.
Normal growth and food c/
consumption. No
gross signs of in-
toxication.
No significant findings. d/
a./ Gol'z and Shaffer, op. cit. (1956).
b/ Frawley et al., op. cit. (1957).
£/ Kalow and Marton, op. cit. (1961).
d/ Holland et al., op. cit. (1952).
69
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Subacute oral and intraperitoneal toxicity - rats - Thirty-three
day, 8 week, and 5 and 6 month subacute feeding studies were conducted
with various concentrations of malathion in the feed of rats. These
data are summarized in Table 12. Golz and Shaffer (1956) conducted a
33-day feeding study with rats fed diets of malathion containing 100,
1,000, and 5,000 ppm. There were no deaths during the period of feed-
ing and no gross signs of toxicity referable to cholinesterase inhibi-
tion. There were no effects on weight gain and food intake. Cholin-
esterase activity of red blood cells was significantly depressed at
1,000 and 5,000 ppm, but cholinesterase activity of brain and liver
was not affected. Plasma cholinesterase was inhibited only at 5,000
ppm. Frawley et al. (1957) showed that feeding rats diets containing
100 and 500 ppm malathion for 8 weeks had no effect on whole blood
cholinesterase activity. Kalow and Marton (1961)— fed male and female
rats malathion in the diet at 4,000 ppm (240 mg/kg) for 5 months. Growth
was normal in these animals and no signs of intoxication occurred. How-
ever, breeding animals exposed to this dietary level of malathion ex-
hibited a smaller average litter size than the control, and the number
of young alive at 7 and 21 days was about half the number in the con-
trol group. Holland et aL (1952)— showed that male and female rats
tolerated diets containing 1,000 ppm malathion for 6 months without
any adverse effects.
DuBois et al. (1953)—' showed that rats could tolerate 100 mg/kg
daily for 60 days intraperitoneally without mortality, but that after
daily doses for the same period of 200 and 300 mg/kg, the mortality
rate was 60 and 100%, respectively.
Subacute inhalation toxicity - rats - Inhalation experiments were
conducted with rats by Golz (1955)^7 Neither static vapor nor dynamic
flows up to 5 ppm caused significant depression of cholinesterase activ-
ity. The results of investigations are summarized as follows.
I/ Kalow, W., and A. Marton, "Second Generation Toxicity of Malathion
in Rats," Nature, 192(4801):464-465 (1961).
2j Holland, E. G., L. W. Hazleton, and D. L. Hanzal, "Toxicity of Mala-
thion (0,0-Dimethyl Dithiophosphate of Diethyl Mercaptosuccinate),11
Fed. Proc., 11:357 (1952).
3_/ Dubois, K. P., J. Doull, J. Deroin, and 0. K. Cummings, "Studies on
the Toxicity and Mechanism of Action of Some New Insecticidal
Thionophosphates," AMA Arch. Inc. Hyg. Occup. Med.. 8:350-358
(1953).
4_/ Golz, H. H., "Malathion: Summary of Pharmacology and Toxicology,"
American Cyanamid Company (1955).
70
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Method of Duration Mortality
exposure of test (%)
Comments
Static vapor
toxicity
0.12 ppm
Dynamic flow
5 ppm
2 weeks
4 weeks*
0
No significant depression of
cholinesterase activity.
No significant changes observed.
* Eight hours a day, 5 days a week.
Chronic oral toxicity - rats - Several investigators have administered
malathion to the diets of rats at various concentrations. (See Table 13.)
Hazleton and Holland (1953) fed rats malathion (technical 65% as a 25%
wet table powder) in the diet at 100, 1,000 and 5,000 ppm for 2 years. There
were no mortalities at any level. At 5,000 ppm, food intake and weight
gain were reduced. Plasma cholinesterase, cholinesterase of RBC's and
brain cholinesterase activity were reduced at both the 1,000 and 5,000 ppm
levels. There were no significant gross or microscopic findings at
autopsy of these rats. In another study, Hazleton and Holland (1953) fed
malathion (technical 90% as a 25% wettable powder) at 100, 1,000, and
5,000 ppm for 2 years. The essential finding in this study was that the
terminal cholinesterase activity in plasma, erythrocytes and brain was
significantly depressed at all levels of exposure. Golz and Shaffer
(1956) fed malathion (technical 99% as a 25% wettable powder) to male and
female rats for 2 years at levels of 500, 1,000, 5,000 and 20,000 ppm
in the diet. There was marked reduction of growth, food intake and the
cholinesterase activity of brain, plasma and erythrocytes at 20,000 ppm.
The cholinesterase of the erythrocytes was also markedly reduced at
500 ppm. In view of these findings a "no-effect" level of 100 ppm has
been established for rats (Anon., FAO/WHO Report, 1965!'). This is
equivalent in man to 16 mg a day or 0.2 mg/kg body weight per day.
The estimated ADI for man is 0 to 0.02 mg/kg body weight (Anon., FAO/WHO
Report, 1965).
!/ FAO/WHO, "Malathion," 1965 Evaluation of the Toxicity of Pesticide
Residues in Food, 136-141 (1965).
71
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Table 13. .CHRONIC TOXICITY OF MALATHION TO RATS
Concentration of
malathion in feed
(ppm)
Duration
of test
(years)
Mortality
(%) Comments
References
100, 1,000, 5,000
Technical 65%
as 25% wettable
powder
0
100, 1,000, 5,000
Technical 90%
as 25% wettable
powder
500, 1,000, 5,000,
20,000
Technical 99%
as 25% wettable
powder
No gross effects at a,b/
100 and 1,000 ppm.
At 5,000 ppm food
intake and weight
gain were reduced.
Significant depres-
sion of plasma,
erythrocytes and
brain cholinesterase
activity at 1,000
and 5,000 ppm. '
Growth rate and food a,b/
intake not influ-
enced. Significant
depression of cho-
linesterase activ-
ity at all levels
of exposure.
Significant depres- c/
sion of cholinester-
ase activity of
erythrocytes at all
levels of exposure.
Food intake and
growth not affected
at 500 and 1,000 ppm.
a/ FAO/WHO, op_. cit. (1965).
b/ Hazleton and Holland, op. cit. (1953).
c/ Golz and Shaffer, op. cit. (1956).
72
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Acute oral toxicity - mice - A summary of the acute oral toxicity
of malathion to mice is shown in Table 14. The vehicle and the com-
position of the formulations have a considerable influence on absorp-
tion following oral administration to mice. Mice appear to be more
resistant to malathion than rats. Male and female mice appear to be
about equally susceptible to malathion (Hazleton and Holland 1953).
The symptoms of toxicity of mice exposed to toxic doses of malathion
are those due to cholinesterase inhibition. These symptoms include
excessive salivation, depression and tremors. The less severe symp-
toms are usually of short duration and unless death occurs within
several hours, recovery is rapid and apparently complete (Golz and
Shaffer, 1956).
Table 14. ACUTE ORAL TOXICITY OF MALATHION TO MICE
Dose (mg/kg)
Formulation
Technical 99%
Technical 90%
Technical
Technical
Technical 90%
Technical 99%
Technical 65%
Technical 65%
Technical 65%
Measurement
Oral LD50
Oral LD5Q
Oral U>50
Oral LD5Q
Oral LD50
Oral LD50
Oral 11)50
Oral LD5Q
Oral LD50
Male Female
3,321
886
930
775
720
3,330
1,260
930 940
1,158
References
a/
a/
b/
b/
c/
c/
a/
c/
a/
a/ Hazleton and Holland, op. cit. (1953).
b/ Spiller, ^p_. cit. (1961).
£/ Golz and Shaffer, op. cit. (1956).
Acute toxicity routes other than oral - mice - The acute intra-
peritoneal and inhalation toxicity of mice is summarized in Table 15.
A search of the literature revealed that toxicity studies by these
routes of exposure were very few. The intraperitoneal toxicity to
mice is reported to be 815 mg/kg (O'Brien et al., 19581.') and between
420 and 474 mg/kg (Hazleton and Holland, 1953).
I/ O'Brien, R. D., G. D. Thron, and R.,W. Fisher, "New Organophosphates
Insecticides Developed on Rational Principles," J. Econ. Entomol.,
51(5):714-718 (1958).
73
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Tal?le 15. ACUTE TOXICITY OF MALATHION TO MICE -
ROUTES OTHER THAN ORAL
LD5o (mg/kg)
Route MaleFemaleMixed References
Intraperitoneal 815 a/
Intraperitoneal 420-474 b/
Inhalation-static
saturated vapors ^50 8 hr
> 15 mg/m3 c/
a/ O'Brien, et a,!., op. cit. (1958).
b/ Hazleton and Holland, op. cit. (1953).
£/ Golz and Shaffer, op. cit. (1956).
Subacute oral and inhalation toxicity - mice - Mice have been ex-
posed to aerosols containing 5 ppm of malathion for 8 hr a day, 5 days
a week for 4 weeks. There was no significant depression of cholin-
esterase activity or gross pathology associated with the exposure
(Golz, 1955).
Acute oral, intraperitoneal and dermal toxicity - guinea pigs -
The acute oral LDcn in guinea pigs is reported to be 570 mg/kg (Hagan,
1953) . The intraperitoneal LI>5o for guinea pigs is reported to be
500 mg/kg (Spiller, 1961). The acute dermal (Cuff Method—24 hr expo-
sure) LDc0 to guinea pigs is reported to be greater than 12,300 mg/kg
(Golz and Shaffer, 1956). This data is summarized in Table 16:
Table 16. ACUTE TOXICITY OF MALATHION TO GUINEA PIGS
(mg/kg)
Formulation Route Male Female Mixed References
Oral 570 a/
Technical 95% Dermal > 12,300 b_/
Intraperitoneal 500 c/
a/ Hagan, op. cit. (1953).
b/ Golz and Shaffer, op. cit. (1956).
£/ Spiller, op_. cit. (1961).
74
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Subacute and chronic toxicity - guinea pigs - A search of the litera-
ture failed to reveal any data on the subacute or chronic oral toxicity
relative of malathion to guinea pigs.
Subacute, dermal, and inhalation toxicity - guinea pigs - In a sub-
acute dermal experiment shown in Table 17, undiluted malathion was applied
daily at a dose of 1,230 mg/kg for 4 days. Under these conditions mor-
tality occurred (Haller and Simmons, 1952JL/).
Table 17. SUBACUTE DERMAL AND INHALATION TOXICITY OF
MALATHION TO GUINEA PIGS
Route
Dermal
Duration
of test
4 days
Mortality
Comments
Mortality Four daily doses of
occurs 1,230 mg/kg pro-
but percent duces mortality.
unknown.
Inhalation- 2 weeks
static vapor
toxicity
Inhalation- 4 weeks
dynamic flow
5 ppm
0
No significant de-
pression of cho-
linesterase
activity.
No significant de-
pression of cho-
linesterase
activity or gross
pathology.
References
a/
b/
b/
aj Haller and Simmons, op. cit. (1952)
b/ Golz, os.. cit. (1955).
Table 17 also summarizes the subacute inhalation toxicity of mala-
thion to guinea pigs. As shown, there was no gross pathology or bio-
chemical lesion associated with the exposure.
Haller, M. L.% and S. W. Simmons, "Interdepartmental Committee on
Pest Control," J. Econ. Entomol., 45:761-762 (1952).
75
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Acute and chronic oral toxicity - chickens - The acute oral toxicity
of malathion to chickens varies with regard to age. The LD^Q to adult
chickens was greater than 850 mg/kg (Golz and Shaffer, 1956). The LD5o
was 370 mg/kg for chickens 2 to 3 weeks old (Sherman and Ross, 1959.1/).
For chickens 3 to 4 weeks old, the LDcQ was reported to be between 200
and 400 mg/kg, and for 1-year old chickens, the LD5Q was reported to be
between 150 and 200 mg/kg (Spiller, 1961).
Malathion levels of 250 and 2,500 ppm in the diet of male and
female chickens were fed for 2 years. At the higher .level, the plasma
cholinesterase activity was inhibited. There were no effects on hatch-
ability and at autopsy no gross or microscopic lesions were found
(Anon., FAO/WHO Report, 1965). When chickens were fed for 15 weeks
at 10,000 ppm all birds died (Frawley et al., 1956-/).
Subacute oral and dermal toxicity - chickens - Malathion (10 ppm)
was fed to day-old chicks for 2 weeks. For the following 10 weeks,
the chicks were grouped and fed 10, 100, 1,000, and 5,000 ppm in their
diets. No signs of toxicity were noted at doses of 100 and 1,000 ppm;
growth rate and food intake were equal to that of control animals.
Four animals died in the 5,000 ppm group and signs of intoxication and
growth retardation were observed (Anon., FAO/WHO, 1967.1') .
When malathion as a 470 dust was worked into the feathers and
skin of 10-week old hens once a week for 6 weeks, there were no deaths.
Gross symptoms, food intake and weight gain were equal to controls.
There was no significant inhibition of cholinesterase activity (Golz
and Shaffer, 1956).
Acute, subacute and chronic toxicity - dogs - The acute intra-
peritoneal LD^g °f a 957o solution of malathion to dogs is reported
to be 1.51 ml/kg (Guiti and Sadeghi, 1969*/), and the acute intra-
venous UDc0 is reported to be greater than 430 mg/kg but less than
600 mg/kg (Bagdon and DuBois, 19555/).
I/ Sherman, M., and E. Ross, "Toxicity of House Fly Larvae to Insec-
ticides Administered as Single Oral Dosages to Chicks," J. Econ.
Entomol., 52(4):719-723 (1959).
27 Frawley, J. P., R. E. Zwickey, and H. N. Fuyat, "Myelin Degenera-
tion in Chickens with Subacute Administration of Organic Phos-
phorus Insecticides," Fed. Proc., 15:424 (1956).
3/ FAO/WHO, "Malathion," 1966 Evaluation of Some Pesticide Residues
in Food. Geneva, 172-185 (1967).
4/ Guiti, N., and D. J. Sadeghi, "Acute Toxicity of Malathion in the
Mongrel Dog," Toxicol. Appl. Pharmacol.. 15(1):244-245 (1969).
5/ Bagdon, R. E., and K. P. DuBois, "Pharmacologic Effects of Chlor-
thion, Malathion and Tetrapropyl Dithionopyrophosphate in
Mammals," Arch. Int, Pharmacodyn. Ther.. 103:192-199 (1955).
76
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In a subacute inhalation study one dog was exposed to an aerosol
concentration of malathion of 5 ppm daily for 4 weeks. The erythro-
cyte and plasma cholinesterases were reduced to 34% and 52% of normal,
respectively (Anon., FAO/WHO Report, 1965).
No information could be found concerning long-term studies in
dogs.
Acute, subacute and chronic toxicity - cats - A search of the lit-
erature revealed that very little work has been initiated using cats
as the animal species with regard to malathion toxicity. Cats were
reported to have survived an acute oral dose of 500 mg malathion. Cats
were powdered daily for 14 days with 25% dust and dipped in 0.22% emul-
sion without harmful effects (Spiller, 1961). Some additional informa-
tion appears in the behavioral effects subsection.
Acute, subacute and chronic toxicity - rabbits - The acute oral
LD5Q for rabbits is reported to be greater than 900 mg/kg (Adkins et al.,
1955I/).
The acute dermal LD5Q to rabbits is reported to be between 2,460
and 6,150 mg/kg (Haller and Simmons, 1952).
Rabbits are not the animal of choice for subacute and chronic
studies; therefore, no information was found for these types of studies
in rabbits.
Toxicity to Domestic Animals -
Goats - Goats were exposed dermally to malathion as 0.1% and 0.25%
dip solutions without any harmful effects (Golz and Shaffer, 1956).
Sheep - The acute oral LI>50 of malathion to sheep was reported to
be less than 150 mg/kg (Radeleff and Woodard, 195?2/) . The maximum
safe oral dose (MSD) to sheep is reported to be 50 mg/kg, and the
minimum toxic dose (MTD) is 100 mg/kg (Wilber, 19601/).
If Adkins, T. R., Jr., W. L. Sowell, and F. S. Arant, "Systemic Effect
of Selected Chemicals on the Bed Bug and Lone Star Tick When
Administered to Rabbits," J. Econ. Entomol., 48:139-141 (1955).
2J Radeleff, R. D., and G. T. Woodard, "The Toxicity of Organic Phos-
phorus Insecticides to Livestock," J. Am. Vet. Med. Assoc., 130:
215-216 (1957).
3/ Wilber, C. G^, "New Insecticides. Toxicity, Hazards, and Therapy,"
Iowa State Univ. Vet., 23:21-23 (1960).
77
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Cattle - The LD50 of malathion (95% technical) to male dairy calves
is 80 mg/kg and to dairy cows is 560 mg/kg (Golz and Shaffer, 1956). In
other acute LD50 toxicity studies, the oral LD5Q value in cattle has
been reported to be less than 200 mg/kg (Radeleff and Woodard, 1957).
When beef cattle were exposed to a 0.5% spray once a week for 16 weeks, no
gross evidence of toxicity was observed; however, red blood cell cholin-
esterase activity was depressed. Exposure of dairy cattle to 1% emulsion
or to a 0.5% suspension once a week for 2 weeks produced neither gross
symptoms of toxicity nor depression of cholinesterase activity. Expo-
sure of cows and calves to a 1.25% spray for 7 weeks with a total of
six applications, caused depression of cholinesterase activity (Golz
and Shaffer, 1956).
The minimum toxic dose (MTD) of malathion to baby calves was be-
tween 10 and 20 mg/kg (Radeleff et al., 19551/).
Symptomatology and Pathology Associated with Mammals - The symptoms of
poisoning caused by malathion in mammals are those characteristic of
cholinesterase inhibition. The intensity, time of appearance, and dura-
tion of symptoms depend upon the dose and method of application. High
doses result in systemic poisoning and the initial manifestations include
both muscarinic effects such as anorexia, nausea, sweating, vomiting,
diarrhea, salivation, bradycardia, profuse perspiration, pallor, dyspnea,
and nicotinic effects such as muscle twitching and muscle spasm.
Central nervous system symptoms consist initially of restlessness,
discomfort, tremors, confusion, and, later, coma. Respiratory depres-
sion is an important cause of death (Kimmerle and Lorke, 1968). Brain,
plasma and erythrocyte cholinesterase are maximally inhibited in rats
during the first 24 hours. Plasma and brain levels returned to normal
after 12 days and the red blood cells after 28 days following intra-
peritoneal injection (Hazleton and Holland, 1953).
I/ Radeleff, R. D., G. T. Woodard, W. J. Nickerson, and R. C. Bushland,
"Part II. Organic Phosphorus Insecticides," The Acute Toxicity
of Chlorinated Hydrocarbon and Organic Phosphorus Insecticides to
Livestock, USDA Tech. Bull. No. 1122, 36-46 (1955).
78
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Summary - The acute toxicity of malathion .for the rat is summarized in
the following table:
Acute Toxicity of Malathion in the Rat by
Various Routes of Administration
Value
Route of entry Measurement Male Female
Oral LD50 (mg/kg) 1,375-1,845 ' 1,000
Intraperitoneal 11)50 (mg/kg) 750
Intravenous LD50 (mg/kg) 50 50
Subcutaneous LD50 (mg/kg) 1,000
Dermal LD50 (mg/kg) > 4,444 > 4,444
Inhalation LC5o 1 hr (mg/jj) > 60 > 60
Rats have been fed 5,000 ppm of malathion for 33 days without
lethality or any other sign indicating gross toxicity, although blood
cholinesterase was depressed. Red blood cell cholinesterase was de-
pressed where 1,000 ppm were fed to rats for 6 months. Other signs
of toxicity were not observed.
Rats have been fed 100, 1,000, and 5,000 ppm of malathion (tech-
nical 65%, as a 25% wettable powder) for 2 years. There was no mor-
tality at any level. Body weight gain was reduced at 5,000 ppm and
the blood cholinesterase levels were significantly reduced at 1,000
and 5,000 ppm levels.
In another chronic study 500, 1,000, 5,000 and 20,000 ppm of mala-
thion (technical 99% as a 25% wettable powder) was fed to rats for 2
years. There were marked effects (reduced growth and food intake, and
blood cholinesterase activity) at the 20,000 ppm dosage.
A "no effect" level of 100 ppm has been established for rats.
The acute oral LD50 values for malathion in mice ranges from 720
mg/kg to 3,321 mg/kg. The acute intraperitoneal LD50 value ranged from
420 to 815 mg/kg.
There were significant depressions of cholinesterase activity when
mice were exposed to 5 ppm of malathion for 8 hr a day, 5 days a week for
4 weeks in an inhalation chamber.
79
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The acute oral and intraperitoneal LD^g values for guinea pigs are
570 mg/kg and 500 mg/kg, respectively. The dermal LD.-Q for guinea pigs
appears to be greater than 12,300 mg/kg.
The toxicity (^Q) of malathion to chickens appears to vary with
age of the chicken. However, the data are not consistent. (Adults -
800 mg/kg, 1-year old chickens - 150 to 200 mg/kg, 2 to 3 weeks old,
370 mg/kg.)
Malathion levels of 250 and 2,500 ppm have been fed to chickens
for 2 years. There was no effect on hatchability of eggs nor were
gross or microscopic lesions found. In subacute studies, chickens
were fed 10, 100, 1,000 and 5,000 ppm of malathion from 2 through
12 weeks. No toxic symptoms were noted at the lower doses. Four
chickens died on the 5,000 ppm.
The acute oral LD50 value for malathion in dogs is 1.51 ml/kg of
a 95% solution of malathion. RBC and plasma cholinesterase activity
was depressed 6670 and 47%, respectively, when dogs were exposed to
aerosol concentration of 5 ppm daily for 4 weeks.
Cats have been reported to survive an acute oral dose of 500 mg
of malathion.
The acute oral LDijQ for rabbits appears to be above 900 mg/kg.
The acute oral LD^Q for sheep has been reported to be less than
150 mg/kg. The minimum toxic dose is 100 mg/kg.
LD50 values have been reported to be 560 mg/kg for dairy cows and
less than 200 mg/kg for cattle. Dairy calves appear to have an U>50
of 80 mg/kg; the minimum toxic dose has been set between 10 and 20 mg/kg.
The symptoms of malathion poisoning are characteristic of the organo-
phosphate compounds. These symptoms include anorexia, nausea, sweating,
vomiting, diarrhea, salivation, bronchocardia, profuse perspiration,
pallor, tremors and coma.
Metabolism of Malathion
Absorption - Malathion is rapidly absorbed from the gut (Anon., FAO/
WHO Report, 1967). Shah and Guthrie (1970)17 demonstrated that some
I/ Shah, A. H., and F. E. Guthrie, "Penetration of Insecticides
Through the Isolated Midgut of Insects and Mammals,11 Comp. Gen.
Pharmacol., 1:391-399 (1970).
80
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malathion penetrated mouse gut and some was bound to the gut wall. The
absorption occurred via passive transport and was not related to its
oil/water coefficient. These same authors (1973)17 found that malathion
gut penetration in the mouse was greater in the colon, less in the rectum
and least in the small intestine. Absorption of malathion through the
skin and feathers of birds is slight (March et al., 1956a2/).
o/
Distribution - Pasarela et al. (1962)-' could not detect malathion in
livers, blood, kidneys, hearts, muscle or fat of calves fed 200 ppm
malathion for 41-44 days. There was a small amount (less than 1 ppm)
in the livers of calves sacrificed after 14 days exposure. Malathion
was detected in milk of cows after exposure to 800 ppm in the feed.
Claborn et al. (1956)^-' sprayed cattle with 0.5 to 1.0% malathion and
found 0.08 to 0.36 ppm of malathion in the milk 5 hr later. Only traces
of malathion were detected in the milk at 24 hr and none at 3 or 7 days
later. No malathion was detected in the body fat 1 week after 16 spray-
ings with 0.5% malathion. O'Brien et al. (1961)-' reported 0.11 ppm of
some unidentified metabolite in cows1 milk after ingestion of malathion.
March et al. (1956b)£/ found that heifer calves sprayed twice with 1 pint
of 0.5% malathion had tissue concentrations of 32P ranging from 0.05 to
0.20 ug p/g of tissue 1 to 2 weeks later. Exceptions were liver (1.2
to 0.99 ug 32P/g), bone (1.37 to 1.91 ug 32P/g), and hide (3.24 to 18.5
ug 32P/g).
If Shah, P. V., and F. E. Guthrie, "Penetration of Insecticides Through
Isolated Sections of the Mouse Digestive System: Effects of Age
and Region of Intestine," Toxicol. Appl. Pharmacol., 25:621-624
(1973).
2/ March, R. B., T. R. Fukuto, R. L. Metcalf, and M. G. Maxon, "Fate
of 32P-Labeled Malathion in the Laying Hen, White Mouse, and
American Cockroach," J. Econ. Entomol., 49:185-195 (1956a).
37 Pasarela, N. R., R. G. Brown, and C. B. Shatter, "Feeding of Mala-
thion to Cattle: Residue Analyses of Milk and Tissue," J. Agr.
Food Chem., 10(1):7-9 (1962).
kl Claborn, H. V., R. D. Radeleff, H. F. Beckman, and G. T. Woodard,
"Malathion in Milk and Fat From Sprayed Cattle," J. Agr. Food
Chem., 4(11):941-942 (1956).
5/ O'Brien, R. D., W. C. Dauterman, and R. P. Niedermeier, "The Metab-
olism of Orally Administered Malathion by a Lactating Cow,11 J. Agr.
Food Chem.. 9:39-42 (1961).
6J March, R. B., R. L. Metcalf, T. R. Fukuto, and F. A. Gunther, "Fate
of 32P-Labeled Malathion Sprayed on Jersey Heifer Calves," J. Econ.
Entomol.. 49:679-682 (1956b).
81
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Excretion - O'Brien et al. (1961) reported that 90% of a 32P-malathion
dose excreted by lactating cows was found in the urine. The principal
fecal metabolite was dimethyl phosphate. However, 23% of the dose was
not recovered over a 3-week period. In 1967, O'Brien reported that the
urinary excretion of malathion metabolites consisted of 7% desmethyl
malathion in the cow, 11% in the rat and 21% in the dog. Other princi-
pal urinary metabolites were malathion mono- and di-acids. These were
63 and 17% in the cow, 12 and 48% in the rat, and 40 and 21% in the dog.
The excretion of malathion has been reviewed (Anon., FAO/WHO Report,
1967). In addition to the above information it was reported that the
malathion mono-acid was excreted early during the post-treatment period
while the di-acid appeared later in the observation period. In feces,
85% of the labeled material excreted was malathion, 12% was malaoxon.
Biotrans formation -
Activation - Metcalf and March (1953)i' demonstrated that activation
of malathion was necessary for inhibition of acetylcholinesterase activity.
DuBois and Kinoshita (1968)2/ demonstrated that the activation reaction
was a desulfuration of malathion and conversion to malaoxon. Earlier
'O'Brien (1957)2.' had shown that mouse liver microsomes could convert
malathion to malaoxon and that NADH, Mg++ and nicotinamide were required.
Later O'Brien (1967)2/ reported that the activation reaction (conver-
sion of malathion to malaoxon) by microsomes required NADH2 or NADPH2,
\ /S \ /°
Mg++ and nicotinamide for the conversion of P to P' . He also
postulated a peroxide intermediate for the metabolic conversion accord-
ing to the following scheme:
H202
17 Metcalf, R. L., and R. B. March, "Further Studies on the Mode of
Action of Organic Thionophosphate Insecticides," Ann. Entomol. Soc.
Amer., 46:63-74 (1953).
2J DuBois, K. P., and F. K. Kinoshita, "Influence of Induction of
.Hepatic Microsomal Enzymes by Phenobarbital on Toxicity of Organic
Phosphate Insecticides," Proc. Soc. Exp. Biol. Med., 129:699-702
(1968).
3j O'Brien, R. D., "Properties and Metabolism in the Cockroach and
Mouse of Malathion and Malaoxon," J. Econ. Entomol., 50(2):
159-164 (1957).
kl O'Brien, R. D., Insecticides; Action and Metabolism, Academic
Press, New York (1967).
82
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While direct evidence was lacking for a role of peroxide in malathion
metabolism, it has been shown that NADH2 and liver microsomes do pro-
duce
Degradation - Krueger and O'Brien (1959)!/ found seven metabolites
of malathion in the mouse, using ion exchange chr omatogr aphy . The
mouse detoxified 70 to 80% of a dose in 1/2 hr. The metabolites were
68% malathion monoester, 20.5% phosphatase products and 11.5% unknown
(mostly in one ion exchange peak) . The site of enzyme activity is
shown below:
CHo-0\S H 0
J Nil I il
P-S-C-C-0-C2H5 f
' JCarboxylesterases
' T I ^
/ H-C-C-0-
C2H5 act here
Phosphatases HO *•
act here
Cohen and Murphy (1972)—' found that only half of a malaoxon
dose was detoxified by the carboxy lest erase pathway and suggested
that malathion may also act at some noncritical binding sites. O'Brien
(1957) reported earlier that hydrolysis of malaoxon was vigorous in
liver, kidney and lung. Hydrolyzing activity was greater with mala-
thion than malaoxon. Cook and Yip (1958)^/ found that the degradation
of malathion was different than many other organophosphates in that it
was acted upon by carboxy lesterases . Yip and Cook (1959)— reported
that mala thion-hydroly zing enzymes had the greatest affinity for
tries ters, less for diesters and least for monoester s. OFF was also
hydrolyzed by this system, indicating the presence of at least two
esterases. O'Brien (1967) reported that the most common hydrolysis is
by phosphatases . However, the phosphatases that hydrolyze malathion
are different from both acid and alkaline phosphatases. Hydrolysis also
accounts for s:ome demethylation of malathion. Mammals and insects were
If Krueger, H. R., and R. D. O'Brien, "Relationship Between Metabolism
and Differential Toxicity of Malathion in Insects and Mice," J^
Econ. Entomol., 52:1063-1067 (1959).
2/ Cohen, S. D., and S. D. Murphy, "Inactivation of Malaoxon by Mouse
Liver," Proc. Soc. Exp. Biol. Med., 139(4):1385-1389 (1972).
3/ Cook, J. W., and G. Yip, "Malathionase. II. Identity of a Mala-
thion Metabolite," J. Assoc. Off. Agr. Chem., 41:407-411 (1958).
4/ Yip, G., and J. W. Cook, "Malathionase. III. Substrate Specificity
Studies," J. Assoc. Off. Agr. Chem., 42:405-407 (1959).
83
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both reported to convert malathion to the monoacid (O'Brien, 1967),
but insects also produce dimethyl phosphorothioate as a metabolite.
Chiu et al. (1968)i/ substituted the succinate in malathion and
malaoxon with malonate, a-glutarate and p-glutarate. All were metab-
olized by liver carboxylesterase, in vitro. Earlier O'Brien et al.
(1958) had suggested utilizing carboxylesterase activity in various
species to design organophosphates with a selective toxicity. Hassan
and Dautermann (1968)—' found that the d-isomer of malathion was more
toxic to mice than the 1-isomer. Dautermann and Main (1966)^/ tested
several alkoxy analogues of malathion and found that carboxylesterases
were important in both malathion and malaoxon detoxification. Dahm
et al. (1962)—' using rat liver preparations, found that malaoxon
degradation rates exceeded the activation rate so that little cholin-
esterase inhibiting activity resulted in the reaction media. Brodeur
and DuBois (1963) and (1964)^7 demonstrated that weanling rats were more
susceptible to malathion toxicity than adults, and adult females were
more susceptible than adult males. However, testosterone pretreatment
decreased the toxicity of malathion in weanlings, females and castrated
males. Castrated males were as susceptible as females. Malathion
toxicity did not decrease with maturation of castrated weanlings.
Pretreatment of rats with estradiol increased malathion toxicity in all
animals. Stevens et al. (1972)iL' reported that malathion given 1 hr
before hexabarbital increased sleeping time due to inhibition of hexa-
barbital metabolism. It also depressed ethylmnrphine and aniline
I/ Chiu, Y. C., A. Hassan, F. E. Guthrie, and W. C. Dauterman, "Studies
on a Series of Branched-Chain Analogs of Diethyl Malathion and
Malaoxon with Regard to Toxicity and in vitro Enzymatic Reactions,"
Toxicol. Appl. Pharmaeol., 12:219-228 (1968).
2J Hassan, A., and W. C. Dauterman, "Studies on the Optically Active
Isomers of 0,0-Diethyl Malathion and 0,0-Diethyl Malaoxon,"
Biochem, Pharmaeol., 17:1431-1439 (1968).
' 3/ Dauterman, W. C., and A. R. Main, "Relationship Between Acute Toxic-
ity and in vitro Inhibition and Hydrolysis of a Series of Carbalkoxy
Homologs of Malathion," Toxico.1. Appl. Pharmaeol., 9:408-418 (1966).
4/ Dahm, P. A., B. E. Kopecky, and C. B. Walker, "Activation of Organo-
phosphorus Insecticides by Rat Liver Microsomes," Toxicol. Appl.
Pharmaeol., 4:683-696 (1962).
5_/ Brodeur, J., and K. P. DuBois, "Ali-Esterase Activity and Sex Dif-
ference in Malathion Toxicity," Fed. Proc., 23(2):200 (1964).
6/ Stevens, J. T., R. E. Stitzel, and J. J. McPhillips, "Effects of
Anticholinesterase Insecticides of Hepatic Microsomal Metabolism,"
J. Pharmaeol. Exp. Ther., 181(3):576-583 (1972).
84
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metabolism. Later, Stevens and Greene (1973)!/ found that the inhibi-
tion of ethylmorphine metabolism by malathion, in vitro, was not cor-
related with NADPH oxidation, cytochrome c reduction or cytochrome
P-450 reduction. There was a relationship between the inhibition of
ethylmorphine metabolism by malathion and malaoxon and the binding
affinity of these agents to cytochrome P-450 obtained from rats pre-
treated with bis-p_-nitrophenyl phosphate.
Ruminants may be protected to some degree from the oral toxicity
of malathion by rumen fluid, since Cook (1957)^ showed that this
destroys malathion jLn vitro. Schwartz et al. (1973)!/ found that mala-
thion did not affect rumen microbial function.
Potentiation - In 1957, Frawley et al. reported that the simul-
taneous administration of EPN (0-Ethyl-O-p-nitrophenyl phenylphosphoro-
thioate) and malathion to dogs resulted in a 50-fold increase in mala-
thion toxicity. This effect was less pronounced in rats. Further
studies demonstrated that this was not the result of a chemical inter-
action but a chemical-biological action. Murphy and DuBois (1957)*/
found that EPN inhibited the enzyme which detoxified malathion both
in vivo and in vitro. The highest enzyme concentration was in the
liver, but some activity occurred in serum, kidney and lung. At about
the same time, Cook et al. (1957) postulated that EPN inhibited
esterase cleavage of malathion as a mechanism of potentiation. DuBois
(1958).r_/ pointed out the potential hazards associated with possible
pesticide-drug interaction-potentiation.
Knaak and O'Brien (I960)—' reported that carboxylesterases are in-
hibited by EPN both in vivo and in vitro.
I/ Stevens, J. T., and F. E. Greene, "Response of the Mixed Function
Oxidase System of Rat Hepatic Microsomes to Parathion and Mala-
thion and Their Oxygenated Analogs," LifeSci.,13:1677-1691 (1973).
2f Cook, J. W., "In vitro Destruction of Some Organophosphate Pesti-
cides by Bovine Rumen Fluid," J. Agr. Food Chem.. 5(11):859-863
3_/ Schwartz, C. C., J. G. Nagy, and C. L. Streeter, J. Anim. Sci., 37(3):
821-826 (1973).
4/ Murphy, S., and K. DuBois, "Quantitative Measurement of Inhibition of
•the Enzymatic Detoxification of Malathion by EPN (Ethyl-p-nitro-
phehyl Thiobenzenephosphonate)," Proc. Soc. Exp. Biol. Med.. 96(3):
813-818 (1957).
5/ DuBois, K. P., "Potentiation of the Toxicity of Insecticidal Organic
Phosphates," AMA Arch. Ind. Health, 19:488-496 (1958).
61 Knaak, J. B., and R. D. O'Brien, "Effect of EPN on in vjvo Metabolism
of Malathion by the Rat and Dog," J. Agr. Food Chem., 8:198-203
(1960).
85
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Main and Braid (1962)i/ partially purified rat and human liver
aliesterases and found that they converted 1 mole of malathion to 1 mole
of malathion monoacid. They found that rat serum had some aliesterase
activity but human blood had none. Rat aliesterases, but not cholin-
esterases, were totally inhibited by tri-0-tolyl phosphate (TOTP). They
also found that TOTP increased malathion toxicity almost 100-fold. They
concluded that aliesterases govern malathion toxicity and their inhibi-
tion was largely responsible for potentiation by other organophosphates.
Brodeur and DuBois (1964) demonstrated that malathion was hydrolyzed
mainly by rat liver aliesterases. Pretreatment of animals with pheno-
barbital decreased the toxicity of malathion by stimulating liver
aliesterases. TOTP abolished this reduced toxicity brought about by
phenobarbital. Sex differences in the acute toxicity of malathion
appears to be closely related to unequal levels of aliesterases in the
livers of male and-female rats; stimulation of liver enzymes in females
abolishes this sex difference in malathion toxicity.
9 /
Keplinger and Deichmann (1967)— reported some potentiation of
malathion with chlordane plus parathion. However, they found an antag-
onism between malathion and aldrin or DDT.
Cohen and Murphy (1971)—' reported that EPN potentiation was more
closely associated with inhibition of triacetin esterases than diethyl-
succinate, methyl butyrate or malathion esterases. Treatment with
5 mg/kg parathion inhibited diethylsuccinate, triacetin and methyl-
butyrate esterases 757o but did not potentiate malathion toxicity.
They presented evidence that carboxylesterase inhibition is not suf-
ficient to predict potentiation. Later, Cohen et al. (1972)^-7 found
that TOTP inhibited carboxylesterase activity, but further TOTP in-
creased inhibition of liver binding of malaoxon and increased acetyl-
cholinesterase inhibition. They concluded that potentiation may be by
I/ Main, A. R., and P. E. Braid, "Hydrolysis of Malathion by Ali-
Esterases in vitro and in vivo," Biochem. J.. 84:255-263 (1962).
2/ Keplinger, M. L., and W. B. Deichmann, "Acute Toxicity of Combina-
tions of Pesticides," Toxicol. Appl. Pharmacol.. 10:586-595 (1967)
3_/ Cohen, S. D., and S. D. Murphy, "Carboxylesterase Inhibition as an
Indicator of Malathion Potentiation in Mice," J. Pharmacol. Exp.
Ther., 176(3):733-742 (1971).
4_/ Cohen, S. D., J. E. Callaghan, and S. D. Murphy, "Investigation of
Multiple Mechanisms for Potentiation of Malaoxon1s Anticholin-
esterase Action by Triorthotolyl Phosphate," Proc. Soc. Exp. Biol.
Med., 141(3):906-910 (1972).
86
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multiple mechanisms rather than a single inhibitory process. A further
discussion of TOTP and potentiation of malathion has been presented by
DuBois (1972).!'
Miscellaneous reactions - O'Brien (1956)-/ reported that malathion
not only inhibited cholinesterase but also succinoxidase. Murphy (1966)3-/
found an increase in rat liver alkaline phosphatase and tyrosine-a-
ketoglutarate transaminase after malathion poisoning. This was thought
to be mediated through adrenal function since a similar response was
obtained with injected glucocorticoids. Murphy et al. (1968)^/ found
that malathion was a poor inhibitor of brain cholinesterase, in vitro,
but malaoxon was a good inhibitor. Feland and Smith (1972)57 found a
decrease in liver hexosamine and a decrease in SO^ uptake after mala-
thion treatment, indicating a loss of mitochondrial mucopolysaccharide.
A decrease in mitochondrial swelling confirmed membrane damage. Ramu
and Drexler (1973)-' induced hyperglycemia in fasted rats with toxic
doses of malathion. This was prevented by atropine but not by pre-
treatment with reserpine or ganglion blockade.
Tissue Accumulation - There is no evidence for long-term accumulation
of malathion or malaoxon in the tissues (Pasarela et al., 1962; Claborn
et al., 1956; O'Brien et al., 1961; March et al., 1956a and b).
I/ DuBois, K. P., "The Interaction of Environmental Chemicals With
Drugs," Drug Info. J., 6(l):53-58 (1972).
2_/ O'Brien, R. D., "The Inhibition of Cholinesterase and Succinoxidase
by Malathion and Its Isomer," J. Econ. Entomol.. 49(4):484-490
(1956).
3_/ Murphy, S. D., "Response of Adaptive Rat Liver Enzymes to Acute
Poisoning by Organophosphate Insecticides," Toxicol. Appl.
Pharmacol., 8:266-276 (1966).
4/ Murphy, S. D., R. R. Lauwerys, and K. L. Cheever, "Comparative Anti-
cholinesterase Action of Organophosphorus Insecticides in Verte-
brates," Toxicol. Appl. Pharmacol., 12:22-35 (1968H
5_/ Feland, B., and J. T. Smith, "Malathion Intoxication and Mitochondrial
Damage," J. Agr. Food Chem.. 20(6):1274-1275 (1972).
6/ Ramu, A., and H. Drexler, "Hyperglycemia in Acute Malathion Intoxi-
cation in Rats/1 Isr. J. Med. Sci.. 9<5):635-639 (1973).
87
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Summary
1. Malathion is readily absorbed from the gastrointestinal tract
by passive transport, and poorly absorbed from skin.
2. Very low concentrations of malathion are widely distributed
in tissues. Concentrations in liver and bone are somewhat
higher.
3. Malathion metabolites are mostly excreted in urine. In mammals
these urinary metabolites are mainly mono- and di-acids of
malathion.
4. Malathion requires activation for anticholinesterase activity
by conversion from the thiol to its oxygen analogue.
5. Activation is at the microsomal level and requires NADH2,
Mg++ and nicotinamide.
6. Malathion is degraded by phosphatases and carboxylesterases
or aliesterases.
7. Malathion toxicity is potentiated by EPN, TOTP and possibly
some other organophosphates. Potentiation has been postulated
to be mediated via carboxylesterase or aliesterase inhibition,
but the mechanism is not fully understood. Some evidence
indicates that potentiation may be via multiple mechanisms.
Effects on Reproduction
The effects of malathion on reproduction in laboratory animals,
avian species and domestic animals are reviewed in the following para-
graphs .
Laboratory Animals - Rats have been fed a diet that contained 4,000 mg
of malathion per kilogram of diet. The daily intake approximated 240
mg/kg of body weight of malathion (Kalow and Marton, 1961). The number
of newborn rats that were alive at 7 days was 105 for the controls and
56 for the treated animals. The number of newborn alive at weaning
(21 days) for the controls was 75, and 34 for the treated animals. Nine
weeks after birth the average body weight for the controls was 152 g and
the body weight of the treated rats was 136 g. The retardation of the
treated group was significant at the 1% level.
88
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Avian Species - Ross and Sherman (I960)!' investigated the effects of
feeding malathion on growth and egg production. The malathion was in-
corporated in the feed of chickens at 100 mg/lb of feed for the first
4 weeks, followed by an increase to 200 mg/lb from the 5th to the 7th
week, and up to 500 mg/lb through the 8th to the 29th week. The birds
consuming malathion showed a lower weight gain compared to the controls,
and during the test period there was a 25% mortality of the birds con-
suming malathion. The inclusion of the test amounts of malathion did
not significantly reduce egg production.
Marliac and Mutchler (1963)1' injected eggs with 50 mg of mala-
thion and produced chicks with bleached feathers and slightly shortened
legs. Chicks hatched from eggs injected with 1 mg of EPN had no appar-
ent limb malformations, but showed varying degrees of paralysis. When
25 mg of malathion and 0.5 mg of EPN were combined in an injection, a
decrease in hatchability resulted, along with severely deformed legs,
parrot beak, and feather inhibition in most cases.
3 /
Dunachie and Fletcher (1969)— conducted a study of the effect of
injection of insecticides on the hatchability of hen eggs. They re-
ported that the hatchability of eggs injected with 25, 100, 200, 300,
400, and 500 ppm of malathion dissolved in acetone was 85, 87, 62, 71, 42
and 6%, respectively. When the eggs were injected with 50, 100, and
200 ppm of malathion dissolved in corn oil, the hatchability was 84,
9, and 9%.
Dunachie and Fletcher (1969) also showed that injection of mala-
thion in combination with Ethion (25/75,* 75/25), Mercarbam (25/75,
50/50), Trichlorphon (25/75), and Morphothion (25/75, 75/25) brought
about an enhanced depressant effect on hatchability of hen eggs.
I/ Ross, E., and M. Sherman, "The Effect of Selected Insecticides on
Growth and Egg Production When Administered Continuously in the
Feed," Poult. Sci., 39:1023-1311 (1960).
2_/ Marliac, J. P., and M. K. Mutchler, "Use of the Chick Embryo Tech-
nique for Detecting Potentiating Effects of Chemicals," Fed.
Proc., 22:188 (1963).
3/ Dunaehie, J. F., and W. W. Fletcher, "An Investigation of the
Toxicity of Insecticides to Birds' Eggs Using the Egg-Injection
Technique>' Ann. Appl. Bio., 64(3)^:409-423 (1969)-
* 25/75 indicates 25 ppm malathion with 75 ppm Ethion, etc.
89
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Sauter and Steele (1972)!' fed malathion to chickens at 0.1, 1.0
and 10.0 ppm malathion (5% wettable powder). The fertility of the
eggs from chickens treated with these levels of malathion was not
affected. However, the hatchability of fertile eggs was reduced at
the 1 ppm level from 94.147. (control) to 85.4%, and the 10 ppm level
forced this value down to 81.6%. It appeared that egg production was
somewhat depressed by 0.1, 1.0 and 10.0 ppm malathion. There was
some effect on embryonic death (57o increase over controls for the
1.0 ppm and the 10 ppm malathion treated birds).
Hill et al. (1971)1' investigated the effects of ultralow vol-
ume applications of malathion in mosquito control in Hale County,
Texas, with emphasis of the study being on the effect on nontarget
animals. The amount of malathion used was 3 fl oz/acre. Nine sprays
were conducted over the City of Plainview, Texas. The effect of spraying
on house sparrows was selected for observation because of their density
and commensal relationship with man. The weekly avian total popula-
tion increased during the summer. No decline was indicated that might
be in any way related to the spraying operation. No indications were
evident in the house sparrows' population of anomalies in mating,
nesting, or aggressiveness.
Domestic Animals - Beck (1953)—' made a study of a number of insecti-
cides on the metabolism and motility of boar spermatozoa. He eval-
uated the effect of these compounds on respiration, glycolysis, and
motility. The presence of malathion had little, if any, effect on
any of the parameters. If there was a perceptible effect, it was
that the action of malathion on sperm mortality when exposed for 120
min, reduced the population to a level of nonmotility. It was postu-
lated that the insecticide inhibited motility by altering the permea-
bility of the cell membrane.
I/ Sauter, E. A., and E. E. Steele, "The Effect of Low Level Pesti-
cide Feeding on the Fertility and Hatchability of Chicken Eggs,"
Poult. Sci., 51:71-76 (1972).
21 Hill, E. F., D. A. Eliason, and J. W. Kilpatrick, "Effects of Ultra-
Low Volume Applications of Malathion in Hale County, Texas. III.
Effect on Nontarget Animals," J. Med. Entomol., 8(2):173-179 (1971)
3_/ Beck, S. D., "Effect of Insecticides on the Metabolism and Motility
of Mammalian Spermatozoa," J. Econ. Entomol., 46:570-574 (1953).
90
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Teratogenic Effects
Mammals - Kimbrough and Gaines (1968)!/ studied the effect of intra-
peritoneally injected malathion on the rat fetus. The highest non-
fatal dosage level (900 mg/kg of body weight) was chosen for the
reproduction studies and 12 female rats were divided into two groups
of six for each dosage level (600 and 900 mg/kg) of each compound.
On day 11 after insemination, the pregnant rats were given a single
intraperitoneal injection of malathion. They found no significant
difference between the malathion treated females and the controls,
relative to dead fetuses per litter, resorptions, average weight of
fetuses, average weight of placenta or malformations of the fetuses.
They suggested that feeding studies rather than intraperitoneal in-
jections were a more practical approach to establishing teratogenic
effects for compounds since human exposure would most likely occur
this way.
Avian Embryotoxicity - There have been a number of investigations of
the effects of malathion as related to embryo development (Walker, 1967;
Walker, 1968; Khera and Lyon, 1968; Upshall et al., 1968; Roger et al.,
1969; Dunachie and Fletcher, 1969; Walker, 1971; Sauter and Steele,
1972; Ho and Gibson,
I/ Kimbrough, R. D., and T. B. Gaines, "Effect of Organic Phosphorus
Compounds and Alkylating Agents on the Rat Fetus," Arch. Environ.
Health. 16:805-808 (1968).
2J Walker, N. E., "Distribution of Chemicals Injected into Fertile Eggs
and Its Effect Upon Apparent Toxicity," Toxicol. Appl. Pharmacol.,
10:290-299 (1967).
3/ Walker, N. E., "Use of Yolk-Chemical Mixtures to Replace Hen Egg
Yolk in Toxicity and Teratogenicity Studies," Toxicol. Appl.
Pharmacol.. 12:94-104 (1968).
4/ Khera, K. S., and D. A. Lyon, "Chick and Duck Embryos in the Eval-^
uation of Pesticide Toxicity," Toxicol. Appl. Pharmacol., 13:
1-15 (1968).
5J Upshall, D. G., J. C. Roger, and J. E. Casida, "Biochemical Studies
in the Teratogenic Action of Bidrin and Other Neuroactive Agents
in Developing Hen Eggs," Biochem. Pharmacol., 17:1529-1542 (1968).
j6/ Roger, J. C., D. G. Upshall, and J. E. Casida, "Structure-Activity
and Metabolism Studies on Organophosphate Teratogens and Their
Alleviating Agents in Developing Hen Eggs With Special Emphasis
on Bidrin." Biochem. Pharmacol., 18(2):373-392 (1969).
2J Walker, N. E., "The Effect of Malathion and Malaoxon on Esterases
and Gross Development of the Chick Embryo," Toxicol. Appl.
Pharmacol., 19:590-601 (1971).
8/ Ho, M., and -M. A. Gibson, "A Histochemical Study of the Developing
Tibiotarsus in Malathion-Treated Chick Embryos," Can. J. Zool..
50(10):1293-1297 (1972).
91
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Walker (1967) became interested in the distribution of chemicals
injected into fertile.eggs and their effects upon toxicity. He re-
viewed some observations made by McLaughlin et al. (1963)— who
obtained a 60% hatchability and chickens with leg and feather abnormal-
ities when 0.05 ml of malathion (62 mg) was injected into fertile eggs
prior to incubation. These facts coupled with a report by Greenwood
(Anon., 1966— ), that 5 mg of malathion suspended in corn oil reduced
the hatchability to 28%, but caused no abnormalities, led Walker to
investigate the biological effects and the distribution of malathion
injected alone and in various combinations of vegetable oil. He in-
jected 10 eggs with 0.004 ml (5 mg) of undiluted malathion preincubated
3 days; seven embryos survived 20 days and there were no deformities.
These results were compared with 0.05 ml of malathion and 0.05 ml of
corn oil injected separately into 24 eggs. Eighty-three percent sur-
vived 20 days, and 38% (based on the number of eggs injected) of the
embryos were deformed. The deformities included abnormal down, hooked
beaks, and shortened legs and toes.
Walker (1968) felt that uncontrolled initial movement of the in-
jected material in the yolk could expose the embryo to an overwhelming
amount of chemical immediately or to an unknown concentration after an
indefinite delay. In order to overcome these limitations, Walker tried
yolk chemical mixtures to replace normal egg yolk in teratogenicity
studies. Among the insecticides chosen for the tests was malathion.
His yolk displacement mixtures consisted of 20% salt-glucose-antibiotic
solution and 8070 yolk of an unincubated egg from the source used to
provide the embryo. The results of the injection methods and replace-
ment methods are summarized as follows.
Total mortality (% of number started)
: Treatment Injection method Replacement method
Malathion, 30 umoles/egg 100 38
Malathion, 15 umoles/egg 97 26
Malathion, 7.5 umoles/egg 80 7
Malathion, 3.75 umoles/egg 13
Control 10 27
y McLaughlin, J., Jr., J. P. Marliac, M. J. Verrett, M. K. Mutchler,
and 0. G. Fitzhugh, "The Injection of Chemicals into the Yolk
Sac of Fertile Eggs Prior to Incubation as a Toxicity Test,"
Toxicol. Appl. Pharmacol., 5:760-771 (1963).
2/ "Combinations Raise Insecticide Toxicity,11 Chem. Ene. Mews. 44:28
(1966).
92
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Typical deformities observed were shortened tibiofibulae, shortened toes,
sparse or clubbed down, and hooked beaks or occasionally an elongated
upper beak. Walker felt that embryos treated by yolk replacements sur-
vived better when pesticide levels were high, less well when they were
low, and better when embryos were given injections in corn oil. Ab-
normalities caused by single pesticides or combinations of two pesti-
cides at low levels were more numerous and more severe after yolk replace-
ment.
Walker (1971) has studied the effect of.malathion and malaoxon on
esterases and the gross development of chick embryos. There were very
few survivors of the embroys at the 16th day of incubation when eggs
were treated with 30 umoles of malaoxon. However, about half of those
given 30 umoles of malathion, or 15 umoles of malaoxon, and two-thirds
of those given 15 umoles of malathion survived to 18 to 20 days. Embryos
given 30 umoles of malaoxon were very severely deformed. Some of the
deformities were small body, little or no down, severely deformed legs
and feet, and hooked beak. Embryos given 30 umoles of malathion had
similar but less severe abnormalities. About half of the group that
received 15 umoles of malathion had deformities. However, practically
no deformities occurred in embryos where eggs were exposed to 15 umoles
of malaoxon.
Khera and Lyon (1968) injected a number of pesticides in the yolk
sacs of chicken and duck eggs on incubation days varying from 0, 4, and
7 for hen eggs, and 0, 4, 7, and 10 for duck eggs. They felt that there
was a large variance among replicates, and a lack of dose-response rela-
tionship which would render chicken and duck eggs unsuitable for toxicity
tests. However, when these two avian species were injected on mid-
incubation age (10 days in chick embryos and 13 days in duck embryos),
they were capable, of providing useful information for the assessment of
toxic pesticides. Percent adjusted survivals for chicks and duck embryos
injected in the malathion levels at embryonic age of 10 to 13 days,
respectively are shown as follows.
Adjusted percent survival
chick embryos
Replicate No.
1
2
3
4
1
2
10 ug
74
57
95
86
120
99
93
100 11 g
89
103
95
111
Duck embryos
76
--
1 ing
84
80
95
86
..
98
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These investigators felt that these data indicated a nonmonotonic re-
sponse to dose. The survival of embryos exposed to 1 mg of malathion
was high.
Upshall et al. (1968) studied the teratogenic action of a number
of neuroactive agents in developing hen eggs. They reported that when
they injected (day 4) 1 mg of malathion per egg, no teratogenic signs
were detectable. The length of embryo parts (average of 8 to 25
embryos) indicated no difference between malathion injected eggs and
controls. Furthermore, cholinesterase of the embryo was not decreased.
Roger et al. (1969) also reported that malathion injected into the
egg at a level of 1 mg/egg reduced hatchability to 70% as compared to
the controls at 957o hatchability. There was no indication of parrot
beak, or abnormalities of the legs or feathers.
A histochemical study of the developing tibiotarsus in malathion
tested chick embryos has been reported (Ho and Gibson, 1972). Embryos
were collected at days 8, 10, 12, 14, 16, 18, and 20 of incubation.
The yolk mass in each instance was injected with 0.1 ml of 27o mala-
thion (957o technical) in corn oil on day 5 of incubation. Changes in
the ossification reflected changes in the cartilage model. In general
the tibiotarsi in birds treated with malathion had a reduced rate of
matrix function and a more extensive mineralization pattern.
Mollusca - Davis and Hidu (1969)i/ tested 52 compounds as to their
effects on embryos of the hard clam, Mercenaria mercenaria, and the
American oyster Crassostrea virginica, and on their larvae. The re-
sults of experimentation with malathion in acetone solution are shown
as follows.
Malathion Eggs Larval Difference in
concentration developed survival larval length
(ppm) (7o) (7.) (7,)
0.25 104 90 86
0.50 95 88 90
1.00 101 66 77
2.50 89 52 74
5.00 85 20 72
10.00 42 3 41
I/ Davis, H. C., and H. Hidu, "Effects of Pesticides on Embryonic Devel-
opment of Clams and Oysters and on Survival and Growth of the Larvae,"
Fish. Bull.. 67(2):393-403 (1969).
94
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There was a gradual inhibition in the survival of larvae and in the
percentage increase in length of the larvae as the concentrations
were increased from 0.25 ppm to 10 ppm. At the highest dosage level,
the development of eggs had been reduced to 42%, the survival of the
larvae was down to 3%, and there was only a 41% increase in larval
length. They determined from their data that the TI^ values for 50%
of the eggs of oysters to be normal was 9.07 ppm and the TLm values
for 50% of the larvae to survive was 2.66 ppm.
Behavioral Effects
A study of the effect of malathion on the behavior of cats has
been reported (Spynu, 1957)Ji/. Spynu introduced an oil solution of
malathion of 50 mg/kg in the stomach of cats. The cholinesterase
activity of the plasma was lowered by 45 to 50%. He determined that
there was a latency conditioned reflex in the running time 3 hr after
the administration of the chemical. In another test, the animals were
given 10 mg/kg malathion daily for 10 days. There was an increased
inhibition of cholinesterase activity and a change in the higher
nervous activities. |These disturbances of the strength of the con-
ditioned reflexes and the activity of cholinesterase were especially
evident after an introduction of malathion into the cat at 50 mg/kg,
following the previous poisoning.
21
Kagan, as reported in Medved et al. (1964)— , experimented with
a liquid aerosol of malathion on cats. A concentration of 0.0004 to
0.0008 mg/liter caused a lowering of erythrocyte and serum cholinesterase
activities, by 60% and 41%, respectively. He observed a change in the
strength of the conditioned reflexes in the cat as expressed by the
prolongation of the latency and of running time.
o/
Gershon and Shaw (1961)—' observed the development of the depres-
sive reactions and schizophrenia, along with severe impairment of
memory and difficulty in concentration in 16 subjects exposed for
between 1-1/2 and 10 years to organophosphate insecticides. The
authors concluded that the incidence of psychiatric disorders may be
greater in fruit growing areas than urban areas.
_!/ Spynu, E. I., "The Effect of Some Organophosphorus Insecticides in
the Higher Nervous Activities and on the Cholinesterase Activity,"
The Chemistry and Application of Organophosphorus Compounds, edited
by Acad. Sci., USSR, Moscow (1957), quoted by Medved et al. (1964).
2J Medved, L. I., E. I. Spynu, and Yu. S. Kagan, "The Method of Con-
ditioned Reflexes in Toxicology and Its Application for Determin-
ing the Toxicity of Small Quantities of Pesticides," Residue Rev.,
6:42^74 (1964).
3f Gershon, S., and F. H. Shaw, "Psychiatric Sequelea of Chronic Expo-
sure to Organophosphorus Insecticides," Lancet, 1271-1374 (1961).
95
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Toxicity Studies with Tissue Cultures
Gabliks and Friedman (1965)— investigated a number of insecticides
as to their toxicity in tissue culture. Two cell lines were used — -Chang
liver strain and HeLa (a malignant strain) . Two test procedures were
used for the determination of cytopathogenic effect, inhibition of cell
growth, and total cell protein. The TD^g* ID50> anc* ID10 values f°r
malathion for cytopathogenicity and growth inhibition of liver cells
was 10 ug/ml, 15 ug/ml, and 10 ug/ml, respectively. The response of
HeLa cells to an exposure to malathion was TDcQ - 20 ug/ml; IDcQ -
13 ug/ml; and ID^g - 2 ug/ml. Malathion was cytotoxic in both cell
lines and induced progressive morphological changes leading to the
destruction of cells. The reaction of the two cell lines to mala-
2 /
thion was quite similar. Wilson and Walker (1966)—' worked with the
cells taken from the pectoral region of 14-day old chick embryos and
grown as fibroblasts in monolayers according to standard culture pro-
cedures. Two samples of malathion were used, one 95% purity and the
other 99+% purity. The results from both samples were essentially the
same. It was found that malathion was strongly toxic to the cells above
3.0 x 10 M (10 ug/ml) . This level caused a net decrease in cell num-
ber from the original inoculation, but the decrease was not immediate.
The decline in cell numbers came on rapidly after 24 hr.
3/
Gabliks et al . (1967)— evaluated the toxicological effects of a
number of insecticides in mouse cell cultures. The TD^Q value for
malathion utilizing mouse liver cells was 1,000 ug/ml as compared to
100 ug/ml in mouse skin cells. The n>50 values for malathion was 1,804
Ug/ml in mouse liver cells and 106 ug/ml in mouse skin cells.
It is of interest to compare the growth inhibition levels
Ug/ml) of mouse liver (NCTC No. 1469) and human liver (Chanh strain)
cell cultures determined by Gabliks, et al. (1967). The IDcg levels
(ug/ml) for mouse liver and human liver cell cultures incubated 24, 48
and 72 hr were 200, 160, 5; and 15, 20, and 50, respectively.
I/ Gabliks, J., and L. Friedman, "Responses of Cell Cultures to Insec-
ticides. I. Acute Toxicity to Human Cells," Proc. Soc. Exp.
Biol. Med., 120(1):163-168 (1965).
2_/ Wilson, B. W., and N. E. Walker, "Toxicity of Malathion and Mercapto-
succinate to Growth of Chick Embryo Cells in vitro," Proc. Soc.
Exp. Biol. Med., 12,1(4) : 1260-1264 (1966).
3/ Gabliks, J., M. Bantug-Jurilla, and L. Friedman, "Responses of Cell
Cultures to Insecticides. IV. Relative Toxicity of Several
Organophosphates in Mouse Cell Cultures," Proc. Soc. Exp. Biol.
Med., 125(3):1002-1005 (1967).
96
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In mouse liver cells the IDcQ level of malaoxon is about 11 times less
that of malathion at 48 hr, and it is about 360 times that of malathion
at 72 hr. In Chang liver cells the toxicity of malaoxon is comparable
to that of malathion. These values suggest that marked resistance of
mouse liver cells is due to their inability to oxidize malathion to
malaoxon, whereas human liver cells appear able to transform malathion
to malaoxon. There is another interesting factor of cell culture in
that the concentrations of toxic materials at low levels sometimes
stimulate cell growth. For instance, in mouse liver cells malathion
at 50 ug/ml increased the growth to 160%.
The effects of malathion on mammalian cells relative to compara-
tive cytotoxicity, growth inhibition in acute studies, toxicity in
chronic studies, and advanced resistance of cell culture to malathion
have been reported by Gabliks and Friedman (1969).—' These workers
utilized human cells (Chang liver strain and HeLa strain) and cells of
mouse origin (mouse liver, NCTC .No. 1469, and mouse skin fibroblasts
L-929) . The purity of the test insecticide, malathion, was 99.67o. The
comparative cytopathogenicity and growth inhibition of malathion deter-
mined in human Chang liver and HeLa cells was as follows:
Cytopatho- Growth
genicity inhibition
TD5Q 1^50 ^PlO
(ug/ml)
Cytopatho- Growth
genicity inhibition
TD50 ID5o ID10
(ug/ml)
10 15 10 20 13 2
Gabliks and Friedman (1969) also developed data on the compara-
tive cytotoxicity of malathion to mouse cell cultures as follows :
Growth inhibitory levels ID50
- ug/ml/culture) mg/kg
Mouse Mouse Human liver mouse
liver 1469 skin L-929 Chang (per OS)
1,804 106 15 720-3,300
I/ Gabliks, J., and L. Friedman, "Effect of Insecticides on Mammalian
Cells and Virus Injections," Ann. N.Y. Acad. Sci., 160(Art. 1):
254-271 (1969),
97
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When the data are compared to the preceding data on the comparative
cytotoxicity of malathion to mouse cell culture, it is obvious that
malathion is far less toxic to mouse cell cultures. The investiga-
tors felt that the difference in susceptibility may have been due to the
rates of inactivation to nontoxic derivatives in tissue culture and con-
version to more toxic substances in vivo.
The results were interpreted by the investigator to mean that the
resistance of mouse liver cells to the insecticide could be partially
explained by the inability of mouse liver cells to oxidize malathion
to malaoxon. Evidently the Chang liver cells (human origin) transform
malathion to malaoxon.
Mutagenic Effects
A review of the literature did not reveal any information on the
mutagenic effects of malathion.
Oncogenic Effects
No information was found in the literature concerning the oncogenic
effects of malathion.
Effects on Humans
This section is concerned with the effects of malathion on humans.
Information is presented on acute and subacute toxicity. The symptoms
of malathion poisoning, dermal and inhalation toxicity and the occupa-
tional exposure hazards relative to field operations are discussed.
1 / 2/
Acute Toxicity - Hayes (1967)—' quotes a report by Walters (1957)- that
the largest nonfatal dose of malathion has been 200 mg/kg of body weight.
Walters (1957) indicated that this case involved a 35-year old female
who accidentally ingested 470 ml of a 3% solution of malathion to alle-
viate a toothache. Hayes (1967) referred to a report by Paul (1960)5.'
indicating that the smallest fatal dose has been 71 mg/kg of body weight.
In this instance a 75-year old man ingested 30 to 60 ml of a 5% solution
of malathion.
I/ Hayes, W. J., Jr., "Toxicity of Pesticides to Man—Risks from Present
Levels," Proc. R. Soc. Long.. 167(1007)-.101-127 (1967).
2_/ Walters, M. N. I., "Malathion Intoxication," Med. J. Aust.. 1:876-877
(1957).
3j Paul, A. H., "Poisoning by Organo-Phosphorus Insecticide (Malathion)--
Report of a Case," N.Z. Med. J., 59(335):346-347 (1960).
98
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Goldin et al. (1964)i/ reported on a case of intended self-destruction
which resulted in a dose of 60 g or 1 g/kg of body weight of malathion.
Within 30 min the woman was admitted to the casualty department; the
subject was in a coma. Within 24 hr after treatment the patient's state
of consciousness had improved and she was able to move her arms and
legs sluggishly. The serum cholinesterase activity was less than 22%
of normal for the first 9 days. In these severe cases the use of a res-
pirator is very important.
There is a case history of a woman who had intentionally swallowed
between 35 and 50 g of malathion (Goulding, 19681/). This dosage level
had a clearly profound effect and she would not have survived if it had
not been for the active and specific treatment that she received in the
hospital. Eleven days elapsed before it was possible to wean the
patient from atropine. Namba et al. (1970)-' have referred to reports
of deaths occurring in adults that consumed 5 g (Paul, 1960), 25 g,
35 g, and 70 g (Faraga, 1967ft/) of malathion, and severe poisoning fol-
lowing the ingestion of 15 g (Parker and Chattin, 1955; Gitelson et al.,
19665^67), and 25 e in adults (Richards, 1964; Crowley, 1966; Glaser
and Levin, 1968Zr2/), and 4 g in a 2-year old boy (Tuthill, 1958IP-') .
I/ Goldin, A. R., A. H. Rubenstein, B. A. Bradlow, and G. A. Elliott,
"Malathion Poisoning with Special Reference to the Effect of
Cholinesterase Inhibition on Erythrocyte Survival," N. Engl. J.
Med., 271(25):1289-1291 (1964).
2J Goulding, R., "Toxicological Case Records," Practitioner, 200:599-
600 (1968).
3/ Namba, T. M. Greenfield, and D. Grob, "Malathion Poisoning: A Fatal
Case with Cardiac Manifestations," Arch. Environ. Health, 21(4):
533-541 (1970).
4/ Faraga, A., "Fatal, Suicidal Malathion Poisoning," Arch. Toxicol.,
23:11-16 (1967).
5j Parker, G., Jr., and W. R. Chattin, "A Case of Malathion Intoxication
in a 10-Year Old Girl," J. Indiana State Med. Assoc.. 48:491-492
(1955).
6/ Gitelson, S., L. Aladpemopf , S. Ben-Hadar, and R. Katesalson, "Poison-
ing by a Malathion-Xylene Mixture," JAMA. 197:819-821 (1966).
Tj Richards, A. G., "Malathion Poisoning Successfully Treated with Large
Doses of Atropine," Can. Med. Assoc. J., 91:82-83 (1964).
8/ Crowley, W. J., Jr., and T. R. Johns, "Accidental Malathion Poison-
ing," Arch. Neurol., 14:611-616 (1966).
9/ Glaser, J., and S. Levin, "Malathion Poisoning Due to Hair Shampoo,"
Harefuah, 74:261 (1968).
10/ Tuthill, J. W. G., "Toxic Hazards: Malathion Poisoning," N. Engl. J.
\ Med., 258:1018-1019 (1958).
99
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The actual amount absorbed was reduced by inducing vomiting or gastric
lavage. Matheson and Hardy (1970)17 have reported severe poisoning
following the ingestion of 30 g of malathion.
There has been a report of an attempted suicide case where 30 g of
undissolved malathion was ingested by the subject which was equivalent
to 280 mg of malathion per kilogram of body weight, and the patient
lived (Desnica, 1965^7).
Rider et al. (1959)27 fed one group of five volunteers 16 mg of
malathion daily for 88 days. During the last 41 days they also re-
ceived 3 mg of EPN. No significant depression of RBC or plasma cho-
linesterase was found in the subjects. Another group was fed 6 mg EPN
daily for 88 days. They received 8 mg of malathion the last 44 days
of the test. Both of the groups (10 subjects) were fed 42 days more
on 6 mg EPN and 16 mg of malathion daily. The plasma and RBC cholin-
esterase was depressed by 6 mg of EPN and 16 mg malathion. However,
no toxic signs were detected.
In another study Moeller and Rider (1962)^7 found that 16 mg of
malathion may be ingested daily for as long as 47 days without any
significant affect on plasma or red blood cell cholinesterase activity.
The ingestion of 24 mg daily for 56 days caused a 25% decrease in blood
cholinesterase. The threshold of incipient toxicity appeared to be
24 mg for malathion. The threshold of incipient toxicity is defined
as the maximum amount of the drug being tested that can be ingested
daily for a prolonged period of time without depressing the pretest
level of plasma or red blood cell cholinesterase activity more than 10%.
\] Matheson, I., and E. A. Hardy, "Treatment of Malathion Poisoning,"
"~ Anaesthesia, 25:265-271 (1970).
2f Desnica, G., "A Case of Severe Peroral Poisoning with Malathion,"
Luec. VJesn., 87(4) -.419-424 (1965).
3/ Rider, J. A., H. C. Moeller, J. Swader, and R. G. Devereaux, "A
Study of the Anticholinesterase Properties of EPN and Malathion
in Human Volunteers," Clin. Res., 7:81 (1959).
4/ Moeller, H. C., and J. A. Rider, "Plasma and Red Blood Cell Cholin-
esterase Activity as Indications of the Threshold of Incipient
Toxicity of Ethyl-p_-nitrophenyl Thionobenzenephosphonate (EPN)
and Malathion in Human Beings," Toxicol. Appl. Pharmacol., 4:
123-130 (1962).
100
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Hayes (1971)!/ quoted work by Mattson and Sedlak (I960)- in which one
subject was given a dosage of 58 mg in 1 day and the concentration in
the urine of malathion reached 27 ppm.
o /
Symptoms of Malathion Poisoning - Namba et al. (1971)— have produced
one of the outstanding reviews on symptoms of poisoning due to organo-
phosphate insecticides. These authors listed the acute poisoning due
to organophosphate insecticides to include the following sequence of
events: absorption of organophosphates from the skin, gastrointestinal
tract, conjunctivas, or respiratory tract; conversion of some organo-
phosphates in the liver to a more toxic form, that is, malathion to
malaoxon; transport to the synapses, inhibition of acetylcholinesterase;
accumulation of acetylcholine at the synapses, and initial stimulation
and later inhibition of synapses transmission. The symptoms of organo-
phosphate poisoning are attributable to the accumulation of acetyl-
choline, which produces parasympathetic, sympathetic, motor, and central
nervous system manifestations. The onset of the symptoms may have a
time interval of 5 min after massive ingestion but is usually less than
12 hr and is always less than 24 hr. The usual cause of death is res-
piratory failure, which results from weakness of respiratory muscles
and depression of the respiratory center. Miosis is one of the most
characteristic signs and is found in almost all patients with moder-
ately severe and severe poisoning.
The physiological symptoms characteristic of malathion poisoning
have been described by Namba et al. (1970) and Goulding (1968).
The initial symptoms include such nonspecific features as malise,
anorexia, headache, weakness, anxiety, nausea, and vomiting. Progres-
sive diagnostic symptoms include salivation, sweating, abdominal pains,
wheezing respiration, bradycardia, and visual difficulties. At this
point muscular fasciculation and tremors may occur. As the condition
advances, pinpoint and nonreactive pupils, diarrhea, involuntary defeca-
tion and tenesmus, pronounced bronchoconstriction and pulmonary edema,
cyanosis, convulsions, prostration, and coma may occur.
I/ Hayes, W. J., Jr., "Studies on Exposure During the Use of Anticholin-
esterase Pesticides," Bulletin of the World Health Organization,
44:277-288 (1971).
2/ Mattson, A.-M., and V. A. Sedlak, "Ether-Extractable Urinary Phos-
phates in Man and Rats Derived from Malathion and Similar Compounds,"
J. Agr. Food Chem., 8:107-110 (1960). t
3/ Namba, T., C. T*-Nplte, G. Jackrel, and D. Grob, "Poisoning Due to
Organophosphate Insecticides: Acute and Chronic Manifestations,"
Am. J. Med., 50:475-492 (1971).
101
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Ramu et al. (1973)— observed marked hyperglycemia and glycosuria
without acetonuria in four children who had been exposed to a hair
rinse containing 50% malathion in xylene.
Central nervous system effects of organophosphate poisoning include
electroencephalographic changes which may persist for several weeks
after acute poisoning (Grob et al., 1947±/) .
For diagnosis Namba et al. (1971) felt that the estimate of the
erythrocyte cholinesterase was preferred since it reflects the degree
of inhibition of synaptic cholinesterase. In acute cases, the serum
cholinesterase is inhibited more than 50%. The severity of symptoms
parallels the serum cholinesterase activity. A reduction to 20 to 50%
of normal is considered to be mild poisoning, 10 to 20% of normal value
is classified as moderate to severe poisoning, and less than 10% of the
normal value is severe poisoning.
o /
Varnai (1971)—' reported the pathology observed in a fatality that
had a blood cholinesterase inhibition of 78%. The fatal dose of mala-
thion produced damage and local hemorrhages in the brain, the heart
and lungs, and hepatomegaly. These histopathology studies revealed
perivascular edema, lymphocytes in the cortex, cell and cytoplasm
degeneration, pycnotic nuclei, stasis, and local karyolysis in gangalia
and alveolar emphysema, bronchitis, and hemorrhagic pneumonia. Mucous
membranes in the gastrointestinal tract showed extensive necrosis in
this case.
Dermal Effects - The effects of controlled dermal exposure are discussed
in the following paragraphs. Other information on dermal exposure is
discussed in the section on occupational hazards in field operations
later on in this subsection.
"U Ramu, A., A. E. Slonim, M. London, and F. Eyal, "Hyperglycemia in
Acute Malathion Poisoning," Isr. J. Med. Sci., 9(5):631-634 (1973)
2_/ Grob, D., A. M. Harvey, 0. R. Langworth, and J. L. Lilienthal, Jr.,
"The Administration of Diisopropyl Fluorophosphate (DFD) to Man.
III. Effect on the Central Nervous System with Special Reference
to the Electrical Activity of the Brain," Bull. Johns Hopkins
Hosp., 81:257 (1947).
3/ Varnai, L., "Pathology of Malathion Poisoning," Orv. Hetil., 112:
1651-1653 (1971).
102
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Hayes et al. (1960)1' found that there was no decrease in blood
cholinesterase following the dermal application of 1, 5, or 10% mala-
thion dust applied five times weekly for 8 to 16 weeks. Milby and
Epstein (1964)^7 were interested in the allergic contact sensitivity
to malathion. They worked with 87 male volunteers divided into four
groups. A known concentration of 95% pure malathion in ethanol was
applied to the skin of each individual. The applications were made
with dressings that were left in place 2 days. There was some pre-
treatment in that the subjects in Group 1 had an area of the skin
irritated with a 3-sec freeze with Freon 12 .(dichlorodifluoromethane)
and were then exposed to 10% malathion. Group 2 subjects were exposed
to the same level of malathion but a nonirritated skin site was used.
Groups 3 and 4 were irritated with Freon 12 and then exposed to 1.0
and 0.1% of malathion, respectively. After 30 days all the subjects
were retested with a nonirritating concentration of malathion (1%)
at a new site and this area was observed on 2, 4, and 6 days and graded:
1+ = erythema and edema to 4+= Builae. They found that 10% malathion
produced contact sensitization and that the reactions were strong.
They also found that sensitized persons could react to a very weak
dilution of the malathion. In fact, they would react to a commercial
preparation of 0.9% of malathion and water.
Gutentag (1959)^7 conducted a pilot study to determine the safety
of applying malathion powder (1.1%) dusted over a person's entire body.
Ten volunteers were used for this test and they wore the same set of
fatigue uniforms during the period of exposure. Three ounces of powder
consisting of 98.9% pyrophyllite and 1.1% malathion was applied to the
hair, the axilla, the groin, and the feet in the early morning. During
the first week the volunteers were allowed to shower 8 hr after exposure.
During the second week there were no showers, and the volunteers were
not allowed to change their clothes throughout the 80-hr period. The
third week the men were dusted twice and did not shower during this
time. There were 8 days of dusting during the entire test. There was
no significant change in plasma values of cholinesterase. The RBC
cholinesterase values dropped significantly in all volunteers on July
15. The following day, however, these RBC cholinesterase levels re-
turned to normal. The reason for this was thought to be contamination
I/ Hayes, W. J., Jr., A. M. Mattson, J. G. Short, and R. F. Witter,
"Safety of Malathion Dusting Powder for Louse Control., Bulletin
of the World Health Organization. 22:503-514 (1960).
2/ Milby, T. H., and*W. L. Epstein, "Allergic Contact Sensitivity to
Malathion," Arch. Environ. Health, 9:434-437 (1964).
3/ Gutentag, P. J., "Cutaneous Application of 1.1% Malathion Powder
to Volunteers," Report to the U.S. Army, CWLR 2290 (1959).
103
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of the refrigerated blood with parathion in a laboratory refrigerator.
After that episode the .bloods were not refrigerated. The volunteers
had no complaints from the treatment.
Hayes et al. (1960) investigated the safety of using malathion as
a louse control. The need for this work grew out of the recognition
that DDT and Garrana-BHC had lost their effectiveness for control of
some strains of body lice. Three groups of 10 men each entered the
study in 1959 and four groups of 4 to 10 men entered the study or con-
tinued in it in May of the same year. The malathion (95%) was incor-
porated in talc in concentrations of 0.1 and 5% for the original three
groups, and at 0.1, 5, and 10% during the summer for the latter groups.
The men dusted themselves without their clothing each morning 5 days
per week. They each were assigned 90 g of the appropriate formulation,
and all of the remaining powder that was not used on the skin was sifted
into the clothing. There were only three cases of rash reported through-
out the experiment, all of which occurred in the men that received 5 or
10% malathion. Cholinesterase values were obtained, and the concentra-
tions of 1 and 5% malathion produced no significant change in RBC cho-
linesterase while 10% malathion produced a depletion which approached
but was not statistically significant. They found that the upper limit
of true average absorption of malathion applied to the skin as a powder
is probably slightly less than 10%, and the lower limit is about 4%.
They concluded that malathion was safe for control of human head or
body lice, especially since infrequent applications in small amounts of
1% powder are effective.
Maibach et al. (1971)— made observations on the regional varia-
tion of percutaneous penetration in man. They utilized ^C-labeled
insecticides. This material was applied with a microtype pipette to
a marked site. The dosage was kept at 4 ug/cm . The penetration into
the palm and the ball of the foot was similar to the forearm, whereas
more penetration of malathion was observed from the abdomen and the
dorsal skin of the hand. There was a threefold increase on the fore-
head and a fourfold increase on the axilla relative to the forearm.
_!/ Maibach, H. I., R. J. Feldmann, T. H. Milby, and W. F. Serat,
"Regional Variation in Percutaneous Penetration in Man," Arch.
Environ. Health, 23:208-211 (1971).
104
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Inhalation Effects - Golz (1959)17 exposed 16 male prisoners to sprays
from aerosol bombs of 5 and 20% malathion. Four groups of men were
exposed at one time. In one test the exposure was 3 g of 5% malathion
per 1,000 ft , which was an actual exposure of 0.15 g of malathion per
1,000 ft . In another test the exposure was to 0.6 g, and in a fourth
o
group the exposure was to 2.4 g of actual malathion per 1,000 ft . At
no time did these subjects experience any cholinergic symptoms. The RBC
cholinesterase activities never fell below 90% of normal. There were
some erratic results indicated in the plasma cholinesterase activity in
that two subjects suffered depressions to 55 and 37% of normal, respec-
tively. These exposures were considered to be more severe than might
reasonably be expected to occur in unsupervised domestic use of mala-
thion. Upon careful observation of the test subjects, it was found that
none revealed any significant effects from 84 such exposures in 42 con-
secutive days.
Other information on inhalation effects is discussed in the follow-
ing subsection on occupational hazards.
Occupational Exposure Hazards - Occupational hazards involving pesti-
cides may be related to exposure of workers in field operations and
manufacturing operations. This subsection is devoted to field opera-
tion exposures only. No information was available in the literature
concerning the hazards in a malathion manufacturing plant.
The Threshold Limit Value (TLV) for malathion has been set at 10
mg/m (Anon., Am. Conf. of Govt. Ind. Hygienists, 1971—').
Spraying operations - Caplan et al. (1956)2/ were interested in the
hazards of aerial spraying in populated areas with malathion. The spray
material contained about 7.5% malathion. Atmospheric samples were ob-
tained during the period of spray application. It was found that the
O • ^1
variation was from 0.067 mg/nr5 in unprotected areas to 0.088 mg/m0 in
partially protected areas. Estimates were also made of the amount of
malathion that fell on the various subjects, samples being taken from
the head, shoulders, forearm, hands and legs; values ranged from
I/ Golz, H. H., "Controlled Human Exposures to Malathion Aerosols,"
AMA Arch. Ind. Health. 19:516-523 (1959).
2f Anon., American Conference of Government Industrial Hygienists,
"Documentation of the Threshold Limit Values for Substances in
Workroom Air," 3rd .edition (1971).
3_/ Caplan, P. E.,;D.. Culver, and W. C. Thielen, "Human Exposures in
Populated Areas During Airplane Application of Malathion," AMA
Arch. Ind. Health, 14:326-332 (1956).
105
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O O O
0.45 ug/cm to 2.82 ug/cm for a man outdoors and from 0.25 ug/cm to
0.56 ug/cm^ for a man indoors. They summarized by saying that a human
subject working in the fields exposed to 0.46 Ib/acre of malathion by
airplane spraying receives an inspiratory exposure about five times
greater than a subject working inside. The outdoor skin exposure is
about' four times the indoor skin exposure. Furthermore a subject in
this test on the ground being subjected to these spray conditions (on
a milligram per kilogram basis by skin and respiratory exposures)
received an amount that had to be multiplied by factors of 500,000
and 120,000, respectively, to approach the Lpso °f experimental animals.
These investigators made a calculation on measurements relating to the
man with highest exposure and projected those measurements to a 40-hr
week. They estimated that a man would acquire gradually, over a period
of 1 month, less than 45 mg/kg deposited on his skin and less than 11
mg/kg inspired through his n'ostrils. Compared with 11)59 values f°r
animals, these above values represent 100 to 200 times less than the
acute values. Furthermore, it was the opinion of the investigators
that malathion could be used safely for mosquitoes in populated areas.
Culver et al. (1956)17 studied the dermal and respiratory exposure
of workers applying malathion for the control of mosquitoes. In order
to measure the amount deposited on the exposed skin, the workers wore
absorbent alpha-cellulose headbands and a similar band wrapped around
their ankles under the trouser leg but over the socks. Atmospheric
samples were collected by all-glass impingers at the breathing zone of
the members of the team. During this test 480 samples, including bands
and respirator tabs and gloves, were analyzed for malathion. In addi-
tion, a total of 145 impinger samples were analyzed for the insecticide.
During the spraying operations the highest average atmospheric concen-
tration ranged between 3 and 9 mg/m . These levels were encountered in
the path of the spray at 10, 17, and 25 yards. Most of the skin and
inspiratory exposure curves showed a drop between 10 and 17 yards.
However, in all of the curves there was only a slight drop between 17
and 25 yards. The total exposure time for malathion ranged from 5.23 hr
for a jeep driver to 3.91 hr for one of the field observers. The jeep
driver received the highest skin exposure, which ranged from 32 to 86 mg.
His hand exposure was in the range of 27 to 80 mg. Thus, 85 to 9570 of
his total skin exposure to malathion was that of his supposedly protected
hands (in gloves). Furthermore, the total inspiratory exposures to
I/ Culver, D., P. Caplan, and G. S. Batchelor, "Studies of Human Expo-
sure During Aerosol Application of Malathion and Chlorthion,"
AMA Arch. Ind. Health. 13(6):37-50 (1956).
106
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malathion from the impingement samples were highest for the jeep driver,
and ran from 11 to 21 mg. For the men in the field the total inspiratory
exposures fell in the range of 1 to 5 mg. Throughout the period of
application there were no significant changes attributable to para-
sympathetic overstimulation in any of the field personnel.
Jegier (1964)— assessed the occupational hazards that might exist
from respiratory or dermal exposure of spray operators to malathion.
At the time of the investigation insecticides were being used in apple
orchards and the spraying of field crops which included grain, potatoes,
peas, cabbage, carrots, onions, and strawberries. During this spray
season he measured the respiratory and dermal exposure to 52 subjects.
The air concentration of malathion ranged from 0.41 to 0.76 mg/m . The
actual exposure to malathion ranged from 0.03 to 0.13 mg/man/hr by the
respiratory route and 1.5 to 4.9 mg/man/hr by the dermal route. The
formulation from which the evaluations were derived was malathion (25%
wettable powder) in concentration of 1 to 2.5 lb/100 gal. It was deter-
mined during air-blast spraying at apple orchards and field spraying that
the exposure to malathion was less than 0.01% of the toxic dose.
Wolfe et al. (1967)—' made a study of the potential dermal and
respiratory hazard of workers exposed to selected pesticides. The
information that was obtained involving malathion is given in Table 18.
The dermal exposure from operating a power air-blast sprayer was 30 mg/hr.
This value is higher than reported by Jegier (1964), 2.5 mg/hr. The
values reported here for respiratory intake were comparable to those
reported by Jegier (1964), 0.11 mg/hr versus 0.08 mg/hr. The data in-
dicate that the highest percent toxic dose per hour was 0.02% which was
received by operators using high-pressure power handguns and spraying
of fruit orchards.
Durham et al. (1965)—' investigated the effect of organophosphate
insecticides on mental alertness. These tests involved general
exposure to organophosphate pesticides and were carried out over three
spraying seasons—1960, 1961, and 1962. It was not delineated in the
I/ Jegier, Z., "Health Hazards in Insecticides Spraying of Crops,"
Arch. Environ. Health. 8:670-674 (1964).
2f Wolfe, H. R., W. F. Durham, and J. F. Armstrong, "Exposure-of
Workers to Pesticides," Arch. Environ. Health, 14:622-633 (1967).
3f Durham, W. F., H. R. Wolfe, and G. E. Quinby, "Organophosphorus
Insecticides and Mental Alertness," Arch. Environ. Health. 10:55-56
(1965).
107
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TABLE 18. SPRAYING CONDITIONS RELATED TO DERMAL AND
RESPIRATORY EXPOSURE OF WORKERS TO MALATHIONS/
AI
acre
Formulation (Ib)
r ,
0.04-0.087. 3.4
spray
0.03-0.08% 3.4
spray
47. dust 1.4
s
°° 47. dust 1.4
47. dust 1.4
2.5-57. aerosol
2.5-57. aerosol
-Number of samples
analyzed
Activity Dermal Respiration Value
Operating power air blast, fruit orchard 44 7
Mean
High pressure power hand gun, fruit orchard 94 13 .,
Range
Operating power duster 14 4 ..
Range
Picking beans 1 day after application 194 6 Mean
Range
Picking beans 2 days after application 42 1 Mean
Range
Operation of aerosol machine 166 14 Mean
Range
Observers checking for mosquito control 238 30 Mean
Dermal
(mg/hr)
5.9-59
30
8.4-194
67
17-32
23
< 0.5-28
3.9
< 1.5-4.3
2.1
3.7-53
29
2.3-6.4
4.1
Respiratory
(mg/hr)
0.02-0.24
0.11
0.01-0.25
0.09
0.22-1.23
0.73
< 0.02
< 0.02
0.02-0.10
0.09
0.04-0.09
0.06
Total 7, toxic
dose/hr
.0.002-0.02
0.01
0.003-0.06
0.02
0.01
< 0.001-0.01
0.001
< 0.001
0.001-0.02
0.01
0.001-0.003
0.002
a/ Data from Wolfe et al., op. cit. (1967).
-------
paper, however, as to the days of exposure to any one of the insecti-
cides. The tests were carried out using the Gersoni U test, which is
a self-paced vigilance test of the cross-out type. The other proce-
dure used was an EX test, which was another self-paced vigilance test
using a question sheet and an IBM answer sheet for true-false answers.
A total of 189 cases of suspected organophosphate poisoning were studied
over a 4-year period. These investigators summarized their work by
commenting that there was little or no difference in mental alertness
among the various exposure groups on five of the six parameters mea-
sured. However, with respect to lines completed on the Gersoni U test,
the exposure group (1960 test) did not score as well during the expo-
sure period compared to the nonexposure period; this was the only dif-
ference indicated. Actually, the control group made a better score
during the exposure period than during the nonexposure period. There
is no indication that exposure to organophosphate pesticides at levels
insufficient to produce clinical illness had any important effect on
mental alertness from the results of the complex reaction time test.
Milby and Epstein (1964) had obtained an indication of allergic
manifestations of malathion in a control one-exposure study which led
them to make an investigation in a field survey. They exposed two
groups which were chosen to consist of (1) 157 workers from a mosquito
abatement district and (2) 43 poultry ranchers who had used malathion
for at least one season in the past 3 years.
A 1% freshly prepared solution of 95% malathion and distilled water
was placed on a square of cloth which was applied to the forearms and
was allowed to remain in place 2 days. Three days after the removal,
the site was observed. It was found that among the 157 mosquito abate-
ment workers 37» showed positive reactions, whereas among the poultry
ranchers two of the 43 (4.7%) volunteers had positive reactions.
Watanabe (1972)— analyzed the blood of subjects suspected of acute
and chronic poisoning by malathion as a result of spraying operations.
Of the 20 cases suspected of chronic organophosphate pesticide poison-
ing, 14 were positive in terms of their serum organophosphate pesticide
levels. The range for malathion was calculated to be 0.007 to 1.075 ppm.
These subjects had sprayed various pesticides for 5 to 20 years, but
they had been out of the orchard for at least 6 months before the
I/ Watanabe,'S., "Detection of Organophosphate Pesticides in Blood
Serum from Patients Suspected of Acute and Chronic Pesticides
Poisonings and Its Clinical Significance," Tohoku J. Exp. Med.,
107(3):301-302 (1972).
109
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examination. Blood samples were also taken from 15 cases of acute
poisoning and the range of pesticide found in the blood was 0.002 to
0.57 ppm.
Hayes (1971) summarized the observations of a number of workers
and concluded that in working areas the observed concentrations for
malathion ranged from 0.01 to 0.60 mg/m3 compared to 0.1 x 10"^ mg/m3
in surrounding communities. When these values are compared with the
threshold limit values of 10 mg/m3 which were established in 1971 by
the American Conference of Government Industrialist Hygienists, it
becomes obvious that under most normal spraying or insecticide appli-
cation conditions the concentrations to which humans are exposed are
significantly lower than values considered hazardous.
Accidents - Malathion is one of the pesticides frequently involved
in accidental exposure to pesticides. Preliminary data from the EPA
Pesticide Accident Surveillance System (PASS) show that malathion is
one of the ninth most frequently cited pesticides for all episodes*
reported in 1973. The computerized PASS data base, which generally
includes any data for 1972 through about January 1974, lists a total
of 123 episodes involving accidental exposure to malathion. Data, in
addition to the preliminary information found on the pesticide episode
reporting form (Form ACC-1, December 1972), however, were available
for review on only three of those episodes. These limited data are
not sufficient to establish any relationship between the accidents and
any specific application or use of malathion.
Summary
Effects on Reproduction - The daily intake of 240 mg/kg (4,000 ppm) of
malathion in rats reduced the number of newborn at 7 days of age by
50%.
The inclusion of 100 mg/lb (first 4 weeks), 200 mg/lb (5th through
7th week), and up to 500 mg/lb (8th through 29th week) of malathion did
not appear to affect egg production. When eggs were injected with 25,
100, 200, 300, 400, and 500 ppm, hatchability was reduced to 85, 87, 62,
71, 42, and 6%, respectively. When eggs were injected with malathion
in combination with Ethion, Mecarbum, Trichlorphion and Morphothion, an
enhanced depressant hatchability effect was noted.
Episodes reported include those involving humans, animals, plants,
and area contamination.
110
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When urban areas were sprayed with 3 ounces of malathion per acre,
the house sparrow population was not depleted, and mating and nesting
characteristics were not changed.
The sperm of swine in the presence of malathion does exhibit re-
duced mortality but there is no effect on respiration or glycolysis.
Teratogenic Effects - It has been reported that the injection of 900
mg/kg of body weight of malathion into pregnant rats on the llth day
after insemination did not produce malformation in the young.
It has been reported that the injection of 62 mg of malathion into
hen eggs reduced the hatchability by 60% and anomalies occurred in
the embryos. In general, the injection of a foreign material into the
egg yolk and its action on the embryo depends upon a number of param-
eters; distribution in the yolk, concentration of varied amounts in
possible vital loci, overwhelming levels occurring and the type of
vehicle used in the injection.
The injection of 1 mg of malathion in hens eggs does not bring
about anomalies of the embryo, however, the hatchability may be reduced
by 25%. In one study, the injection of 0.1 ml of a 2% malathion solu-
tion brought about changes in bone ossification.
Oysters are affected by malathion to the extent that 10 ppm will
reduce egg development (42%), survival of larvae (3%) and the difference
in length of larval development (41%).
Behavioral Effects - Studies have been done involving the measuring of
malathion toxicity by latency conditioned reflex. The physiological
effects of small amounts of the chemical can be detected.
Toxicity Studies With Tissue Cultures - Malathion is cytotoxic to both
Chang liver cells (nonmalignant) and HeLa cells (malignant) at con-
centrations above 3 x 10 M (10 ug/ml). The TDcn values for mala-
thion in contact with mouse liver and skin cells was 1,000 ug/ml and
100 iig/ml, respectively. The ID^Q values were 1,804 ug/ml and 106
ug/ml in mouse liver and skin cells, respectively. The IDc0 for
malaoxon is about 11 times (less) that of malathion at 48 hr and 360
times (less) malathion at 72 hr.
Mutagenic and Oncogenic Effects - No information was found in the
literature concerning the mutagenic or oncogenic effects of malathion.
Ill
-------
Effects on Humans - The acute toxic level of malathion reported for
humans appears to vary from 71 mg/kg of body weight for a low dose to
an amount equal to or exceeding 1,000 mg/kg of body weight for a high
dose. Fast therapeutic action averted death in some of the reported
high dose levels.
In controlled studies, 16 mg of malathion have been administered
for 47 days without affecting plasma or red blood cell cholinesterase.
A 25% decrease in blood cholinesterase has been reported for subjects
consuming 25 mg of malathion for 56 days.
Symptoms of Malathion Poisoning - The general characteristics of organo-
phosphorus compounds are exhibited by malathion. Malathion is converted
to malaoxon which is a more toxic form. The sequence of poisoning events
is malaise, anorexia, headache, weakness, anxiety, nausea and vomiting
followed by salivation, 'sweating, vomiting, abdominal pains, wheezing
respiration, bradycardia and visual difficultues. At this point, muscu-
lar fasciculation and tremors set in. In the highly progressive state,
pronounced bronchoconstriction, pulmonary edema, cyanosis, convulsions,
prostration and coma occur.
The pathology of malathion poisoning is generally nonspecific.
Local hemorrhages may occur in the brain, heart and lungs. Mucous
membranes in the gastrointestinal tract may show extensive necrosis.
Dermal Effects - The application of 1, 5 or 10% malathion dust applied
to the skin five times weekly for 8 to 16 weeks does not decrease blood
cholinesterase.
When volunteers were exposed to 0.1, 1.0, and 10% solution of mala-
thion applied to the skin as dressing and retained in contact with the
skin for 2 days, the 1070 solution produced sensitization.
An extensive study of the dermal effects of 1.1% malathion dust
has been made by the Army. The dust was in contact with the subjects
for a period of 3 weeks and during the first week, the contact was
8 hr a day. Throughout the second week, the subjects did not change
clothes for 80 hr. The subjects were dusted twice during the third
week and did not shower. There was no significant depression of RBC
cholinesterase in these volunteers. In another test, there were no
significant toxic effects produced by dusting repeatedly with 5 and 10%
malathion dusts.
112
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Inhalation Effects - It has been reported that no toxic manifestations
have occurred when subjects were exposed 84 times in 42 consecutive
days to a concentration of aerosols ranging from 0.15 mg to 2.4 g of
actual malathion per 1,000 ft-*.
Occupational Exposure Hazards - There have been a number of studies of
the exposure hazard to spray operations in orchards and field crops and
people living in communities where malathion was used for mosquito
abatement. It appears that malathion does not represent any hazard
to humans in these operations. Exposure under spray conditions would
have to be multiplied by a factor of 500,000 and 120,000 to approach
the LD50 °f experimental animals for dermal and respiratory exposure
as reported by one investigator. In another study, the calculated
exposure in spray operations was less than 0.017,, of the toxic dose.
The work of a number of investigators has been examined and the
conclusion was made that the concentration of malathion in working
areas ranges from 0.01 to 0.60 mg/m3 and in communities 0.1 x 10"°
Q ...
mg/m . When these values are compared with the threshold limit values
(TLV) set by the American Conference of Government and Industrial
Hygienists of 10 mg/m3, it is obvious that the exposure hazard of
malathion is very low.
113
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References
Adkins, T. R., Jr., W. L. Sowell, and F. S. Arant, "Systemic Effect of
Selected Chemicals on the Bed Bug and Lone Star Tick When^Administered
to Rabbits," J. Econ. Entotnol., 48:139-141 (1955).
American Conference of Government Industrial Hygienists, "Documentation
of the Threshold Limit Values for Substances in Workroom Air," 3rd edition
(1971).
Bagdon, R. E., and K. P. DuBois, "Pharmacologic Effects of Chlorthion,
Malathion and Tetrapropyl Dithionopyrophosphate in Mammals," Arch.
Int. Pharmacodyn. Ther.. 103:192-199 (1955).
Beck, S. D., "Effect of Insecticides on the Metabolism and Motility of
Mammalian Spermatozoa," J. Econ. Entomol., 46:570-574 (1953).
Boyd, E. M., "Dietary Protein and Pesticides Toxicity in Male Weanling
Rats," Bulletin of the World Health Organization. 40:801-805 (1969).
Brodeur, J., and K. P. DuBois, "Comparison of Acute Toxicity of Anticholin-
esterase Insecticides to Weanling and Adult Male Rats," Proc. Soc. Exp.
Med., 114(2):509-511 (1963).
Brodeur, J., and K. P. DuBois, "Ali-Esterase Activity and Sex Difference
in Malathion Toxieity," Fed. Proc., 23(2):200 (1964).
CapIan, P. E., D. Culver, and W. C. Thielen, "Human Exposures in Popu-
lated Areas During Airplane Application of Malathion," AMA Arch. Ind.
Health. 14:326-332 (1956).
Chiu, Y. C., A. Hassan, F. E. Guthrie, and W. C. Dauterman, "Studies on
a Series of Branched-Chain Analogs of Diethyl Malathion and Malaoxon
with Regard to Toxicity and in vitro Enzymatic Reactions," Toxicol.
Appl. Pharmacol.. 12:219-228 (1968).
Claborn, H. V., R. D. Radeleff, H. F. Beckman, and G. T. Woodard,
"Malathion in Milk and Fat From Sprayed Cattle," J. Agr. Food
Chem.. 4(ll):941-942 (1956).
Cohen, S. D., and S. D. Murphy, "Carboxylesterase Inhibition as an Indi-
cator of Malathion Potentiation in Mice," J. Pharmacol. Exp. Ther.,
176(3):733-742 (1971).
Cohen, S. D., and S. D. Murphy, "Inactivation of Malaoxon by Mouse
Liver," Proc. Soc. Exp. Biol. Med., 139(4):1385-1389 (1972).
114
-------
Cohen, S. D., J. E. Callaghan, and S. D. Murphy, "Investigation of
Multiple Mechanisms for Potentiation of Malaxon's Anticholinesterase
Action by Triorthotolyl Phosphate." Proc. Soe. Exp. Biol. Med., 141(3):
906-910 (1972).
"Combinations Raise Insecticide Activity," Chem. Eng. News, 44:28 (1966).
Cook, J. W., "In vitro Destruction of Some Organophosphate Pesticides
by Bovine Rumen Fluid," J. Agr. Food Chem., 5(11):859-863 (1957).
Cook, J. W., and G. Yip, "Malathionase. II. Identity of a Malathion
Metabolite," J. Assoc. Off. Agr. Chem., 41:407-411 (1958).
Crowley, W. J., Jr., and T. R. Johns, "Accidental Malathion Poisoning,"
Arch. Neurol., 14:611-616 (1966).
Culver, D., P. Caplan, and G. S. Batchelor, "Studies of Human Exposure
During Aerosol Application of Malathion and Chlorthion," AMA Arch.
Ind. Health, 13(6):37-50 (1956).
Dahm, P. A., B. E. Kopecky, and C. B. Walker, "Activation of Organo-
phosphorus Insecticides by Rat Liver Microsomes," Toxicol. Appl.
Pharmacol., 4:683-696 (1962).
Dauterman, W. C., and A. R. Main, "Relationship Between Acute Toxicity
and In Vitro Inhibition and Hydrolysis of a Series of Carbalkoxy Homo-
logs of Malathion," Toxicol. Appl. Pharmacol., 9:408-418 (1966).
Davis, H. C., and H. Hidu, "Effects of Pesticides on Embryonic Develop-
ment of Clams and Oysters and on Survival and Growth of the Larvae,"
Fish. Bull., 67(2):393-403 (1969).
Desnica, G., "A Case of Severe Peroral Poisoning with Malathion," Luec.
Vjesn., 87(4):419-424 (1965).
DuBois, K. P., "Potentiation of the Toxicity of Insecticidal Organic
Phosphates," AMA Arch. Ind. Health. 19:488-496 (1958).
DuBois, K. P., "The Interaction of Environmental Chemicals With Drugs,"
Drug Info. J., 6(l):53-58 (1972).
115
-------
DuBois, K. P., J. Doull, J. Deroin, and 0. K. Cummings, "Studies on the
Toxicity and Mechanism of Action of Some New Insecticidal Thionophos-
phates," AMA Arch. Ihd. Hyg. Occup. Med., 8:350-358 (1953).
DuBois, K. P., and F. K. Kinoshita, "Influence of Induction of Hepatic
Microsomal Enzymes by Phenobarbital on Toxicity of Organic Phosphate
Insecticides," Proc. Soc. Exp. Biol. Med., 129:699-702 (1968).
Dunachie, J. F., and W. W. Fletcher, "An Investigation of the Toxicity
of Insecticides to Birds' Eggs Using the Egg-Injection Technique,"
Ann. Appl. Biol., 64(3):409-423 (1969).
Durham, W. F., H. R. Wolfe, and G. E. Quinby, "Organophosphorus Insecti-
cides and Mental Alertness," Arch. Environ. Health, 10:55-66 (1965).
Faraga, A., "Fatal, Suicidal Malathion Poisonings," Arch. Toxicol.. 23:
11-16 (1967).
Feland, B., and J. T. Smith, "Malathion Intoxication and Mitochondrial
Damage," J. Agr. Food Chem., 20(6)-.1274-1275 (1972).
Food and Agricultural Organization/World Health Organization, "Malathion,"
1965 Evaluation of the Toxicity of Pesticide Residues in Food, 136-141
(1965).
Food and Agricultural Organization/World Health Organization, "Malathion,"
1966 Evaluation of the Toxicity of Some Pesticides in Food. 172-185
(1967).
Frawley, J. P., R. E. Zwickey, and H. N. Fuyat, "Myelin Degeneration in
Chickens with Subacute Administration of Organic Phosphorus Insecti-
cides," Fed^^roc^, 15:424 (1956).
Frawley, J. P., H. N. Fuyat, E. C. Hagan, J. R. Blake, and 0. G. Fitzhugh,
"Marked Potentiation in Mammalian Toxicity from Simultaneous Administra-
tion of Two Anticholinesterase Compounds," J. Phannacol. Exp. Ther..
121:96-106 (1957).
Gabliks, J., and L. Friedman, "Responses of Cell Cultures to Insecticides.
I. Acute Toxicity to Human Cells," Proc. Soc. Exp. Biol. Med., 120(1):
163-168 (1965).
Gabliks, J., and L. Friedman, "Effect of Insecticides on Mammalian C,ells
and Virus Infections." Ann. N.Y. Acad. Sci., 160(Art. 1):254-271 (1969).
116
-------
Gabliks, J., M. Bantug-Jurilla, and L. Friedman, "Responses of Cell Cul-
tures to Insecticides. IV. Relative Toxicity of Several Organophos-
phates in Mouse Cell Cultures," Proc. Soc. Exp. Biol. Med., 125(3):
1002-1005 (1967).
f
Gaines, T. B., "Acute Toxicity of Pesticides," Toxicol. Appl. Pharmacol.,
14:515-534 (1969).
Gershon, S., and F. H. Shaw, "Psychiatric Sequelea of Chronic Exposure to
Organophosphorus Insecticides," Lancet, 1271-1374 (1961).
Gitelson, S., L. Aladpemopf, S. Ben-Hadar, and R. Katesalson, "Poisoning
by a Malathion-Xylene Mixture," JAMA, 197:819-821 (1966).
Glaser, J., and S. Levin, "Malathion Poisoning Due to Hair Shampoo,"
Harefuah, 74:261 (1968).
Goldin, A. R., A. H. Rubenstein, B. A. Bradlow, and G. A. Elliott,
"Malathion Poisoning with Special Reference to the Effect of Cholines-
terase Inhibition on Erythrocyte Survival," N. Engl. J. Med., 271(25):
1289-1291 (1964).
Golz, H. H., "Malathion: Summary of Pharmacology and Toxicology,"
American Cyanamid Company (1955).
Golz, H. H., "Controlled Human Exposures to Malathion Aerosols," AMA
Arch. Ind. Health, 19:516-523 (1959).
Golz, H. H., and C. B. Shaffer, Malathion: Summary of Pharmacology and
Toxicology, American Cyanamid Company, New York, 2-14 (1956 Revised).
Goulding, R., "Toxicological Case Records," Practitioner, 200:599-600
(1968).
Grob, D., A. M. Harvey, 0. R. Langworth, and J. L. Lilienthal, Jr., "The
Administration of Diisopropyl Fluorophosphate (DFD) to Man. III. Effect
on the Central Nervous System with Special Reference to the Electrical
Activity of the Brain," Bull. Johns Hopkins Hosp., 81:257 (1947).
Guiti, N., and D. J. Sadeghi, "Acute Toxicity of Malathion in the Mongrel
Dog," Toxicol. Appl. Pharmacol.. 15(1):244-245 (1969).
Gutentag, P. J., "Cutaneous Application of 1.1% Malathion Powder to Volun-
teers," Report to the U.S. Army, CWLR 2290 (1959).
* ^
Hagan, E. C., "Acute Toxicity of 0,0-Dimethyl Dithiophosphate of Diethyl
Mercaptosuccinate," Pharmacol. Exp. Ther.. 12:327 (1953).
117
-------
Haller, M. L., and S. W: Simmons, "Interdepartmental Committee on Pest
Control," J. Econ. Entomol., 45:761-762 (1952).
Hassan, A., and W. C. Dauterman, "Studies on the Optically Active Isomers
of 0,0-Diethyl Malathion and 0,0-Diethyl Malaoxon," Biochem. Pharmacol.,
17:1431-1439 (1968).
Hayes, W. J., Jr., "Toxicity of Pesticides to Man—Risks from Present
Levels," Proc. R. Soc. Lond., 167(1007):101-127 (1967).
Hayes, W. J., Jr., "Studies on Exposure During the Use of Anticholin-
esterase Pesticides," Bulletin of the World Health Organization,
44:277-288 (1971).
Hayes, W. J., Jr., A. M. Mattson, J. G. Short, and R. F. Witter, "Safety
of Malathion Dusting Powder for Louse Control," Bulletin of the World
Health Organization, 22:503-514 (1960).
Hazleton, L. W., and E. G. Holland, "Toxicity of Malathion: Summary of
Mammalian Investigations," AMA Arch. Ind. Hyg. Qgg.up. Med.,
(1953). •? 'W-
Hill, E. F., D. A. Eliason, and J. W. Kilpatrick, "Effects of Ultra-Low
Volume Applications of Malathion in Hale County, Texas. III. Effect
on Nontarget Animals," J. Med. Entomol., 8(2):173-179 (1971).
Ho, M., and M. A. Gibson, "A Histochemical Study of the Developing
Tibiotarsus in Malathion-Treated Chick Embryos," Can. J. Zool., 50(10):
1293-1297 (1972).
Holland, E. G., L. W. Hazleton, and D. L. Hanzal, "Toxicity of Malathion
(0,0-Dimethyl Dithiophosphate of Diethyl Mercaptosuccinate)," Fed.
Proc., 11:357 (1952).
Jegier, Z., "Health Hazards in Insecticides Spraying of Crops," Arch.
Environ. Health, 8:670-674 (1964).
Kalow, W.,"and A. Marton, "Second Generation Toxicity of Malathion in
Rats," Nature, 192(4801):464-465 (1961).
118
-------
Keplinger, M. L., and W. B. Deichmann, "Acute Toxicity of Combinations
of Pesticides," Toxicol. Appl. Pharmacol.. 10:586-595 (1967).
Khera, K. S., and D. A. Lyon, "Chick and Duck Embryos in the Evaluation
of Pesticide Toxicity," Toxicol. Appl. Pharmacol.. 13:1-15 (1968).
Kimbrough, R. D., and T. B. Gaines, "Effect of Organic Phosphorus Com-
pounds and Alkylating Agents on the Rat Fetus," Arch. Environ. Health,
16:805-808 (1968).
Kimmerle, G., and D. Lorke, "Toxicology of Insecticidal Organophosphates,"
Pflanz.-Nachr. Bayer, 21:111-142 (1968).
Knaak, J. B., and R. D. O'Brien, "Effect of EPN on In Vivo Metabolism of
Malathion by the Rat and Dog," J. Agr. Food Chem., 8:198-203 (1960).
Krueger, H. R., and R. D. O'Brien, "Relationship Between Metabolism and
Differential Toxicity of Malathion in Insects and Mice," J. Econ.
Entomol., 52:1063-1067 (1959).
Mclaughlin, J., Jr., J. Marliac, M. J. Verrett, M. K. Mutchler, and
0. G. Fitzhugh, "The Injection of Chemicals into the Yolk Sac of Fer-
tile Eggs Prior to Incubation as a Toxicity Test," Toxicol. Appl.
Pharmacol.. 5:760-771 (1963).
Maibach, H. I., R. J. Feldmann, T. H. Milby, and W. F. Serat, "Regional
Variation in Percutaneous Penetration in Man," Arch. Environ. Health,
23:208-211 (1971).
Main, A. R., and P. E. Braid, "Hydrolysis of Malathion by Ali-Esterases
In Vitro and In Vivo," Biochem. J.. 84:255-263 (1962).
March, R. B., T. R. Fukuto, R. L. Metcalf, and M. G. Maxon, "Fate of 32P-
Labeled Malathion in the Laying Hen, White Mouse, and American Cock-
roach," J. Econ. Entomol., 49:185-195 (1956a).
March, R. B., R. L. Metcalf, T. R. Fukuto, and F. A. Gunther, "Fate of
32p-Labeled Malathion Sprayed on Jersey Heifer Calves," J. Econ.
Entomol.. 49:679-682 (1956b).
Marliac, J., and M. K. Mutchler, "Use of the Chick Embryo Technique
for Detecting Potentiating Effects of Chemicals," Fed. Proc.. 22:188
(1963),
*
Matheson, I., and E. A. Hardy, "Treatment of Malathion Poisoning,"
Anaesthesia. 25:265-271 (1970).
119
-------
Mattson, A. M., and V. A. Sedlak, "Ether-Extractable Urinary Phosphates
in Man and Rats Derived from Malathion and Similar Compounds," J. Agr.
Food Chem., 8:107-110 (1960).
Medved, L. I., E. I. Spynu, and Yu. S. Kagan, "The Method of Conditioned
Reflexes in Toxicology and Its Application for Determining the Toxicity
of Small Quantities of Pesticides," Residue Rev., 6:42-74 (1964).
Metcalf, R. L., and R. B. March, "Further Studies on the Mode of Action
of Organic Thionophosphate Insecticides," Ann. Entomol. Soc. Amer.,
46:63-74 (1953).
Milby, T. H., and W. L. Epstein, "Allergic Contact Sensitivity to Mala-
thion," Ar£h^_Ejivj^oju_HeaUh, 9:434-437 (1964).
Moeller, H. C., and J. A. Rider, "Plasma and Red Blood Cell Cholinester-
ase Activity as Indications of the Threshold of Incipient Toxicity of
Ethyl-p-nitrophenyl Thionobenzenephosphonate (EPN) and Malathion in
Human Beings," Toxicol. Appl. Pharmacol., 4:123-130 (1962).
Murphy, S., and K. DuBois, "Quantitative Measurement of Inhibition of the
Enzymatic Detoxification of Malathion by EPN (Ethyl-p-nitrophenyl Thio-
benzenephosphonate)," Proc. Soc. Exp. Biol. Med., 96(3):813-818 (1957).
Murphy, S. D., "Response of Adaptive Rat Liver Enzymes to Acute Poisoning
by Organophosphate Insecticides," Toxicol. Appl. Pharmacol., 8:266-276
(1966).
Murphy, S. D., R. R. Lauwerys, and K. L. Cheever, "Comparative Anticho-
linesterase Action of Organophosphorus Insecticides in Vertebrates,"
Toxicol, Appl. Pharmacol., 12:22-35 (1968).
Namba, T., M. Greenfield, and D. Grob, "Malathion Poisoning: A Fatal
Case with Cardiac Manifestations," Arch. Environ. Health, 21(4):533-
541 (1970).
Namba, T., C. T. Nolte, G. Jackrel, and D. Grob, "Poisoning Due to Organo-
phosphate Insecticides: Acute and Chronic Manifestations," Am. J. Med.,
50:475-492 (1971).
O'Brien, R. D., "The Inhibition of Cholinesterase and Succinoxidase by
Malathion and Its Isomer," J. Econ. Entomol., 49(4) -.484-490 (1956).
O'Brien, R. D., "Properties and Metabolism in the Cockroach and Mouse of
Malathion and Malaoxon," J. Econ. Entomol., 50(2):159-164 (1957).
120
-------
O'Brien, R. D., Insecticides; Action and Metabolism, Academic Press, New
York (1967).
O'Brien, R. D., W. C. Dauterman, and R. P. Niedermeier, "The Metabolism
of Orally Administered Malathion by a Lactating Cow," J. Agr. Food
Chem., 9:39-42 (1961).
O'Brien, R. D., G. D. Thron, and R. W. Fisher, "New Organophosphate Insec-
ticides Developed on Rational Principles," J. Econ. Entomol., 51(5):714-
718 (1958).
Parker, G., Jr., and W. R. Chattin, "A Case of Malathion Intoxication in
a 10 Year Old Girl," J. Indiana State Med. Assoc., 48:491-492 (1955).
Pasarela, N. R., R. G. Brown, and C. B. Shaffer, "Feeding of Malathion to
Cattle: Residue Analyses of Milk and Tissue," J. Agr. Food Chem.,
10(1):7-9 (1962).
Paul, A. H., "Poisoning by Organo-Phosphorus Insecticide (Malathion)--
Report of a Case," N.Z. Med. J., 59(335):346-347 (1960).
Radeleff, R. D., G. T. Woodard, W. J. Nickerson, and R. C. Bushland,
"Part II. Organic Phosphorus Insecticides," The Acute Toxicity of
Chlorinated Hydrocarbon and Organic Phosphorus Insecticides to Live-
stock, USDA Technical Bulletin No. 1122, 36-46 (1955).
Radeleff, R. D., and G. T. Woodard, "The Toxicity of Organic Phosphorus
Insecticides to Livestock," J. Am. Vet. Med. Assoc., 130:215-216 (1957).
Ramu, A., and H. Drexler, "Hyperglycemia in Acute Malathion Intoxication
in Rats," Isr. J. Med. Sci., 9(5):635-639 (1973).
Ramu, A., A. E. Slonim, M. London, and F. Eyal, "Hyperglycemia in Acute
Malathion Poisoning," Isr. J. Med. Sci.. 9(5):631-634 (1973).
Richards, A. G., "Malathion Poisoning Successfully Treated With Large
Doses of Atropine." Can. Med. Assoc. J., 91:82-83 (1964).
Rider, J. A., H. C. Moeller, J. Swader, and R. G. Devereaux, "A Study
of the Anticholinesterase Properties of EPN and Malathion in Human
Volunteers," Clin. Res., 7:81 (1959).
Roger, J., D. G. Upshall, and J. E. Casida, "Structure-Activity and
Metabolism Studies "on Organophosphate Teratogens and Their Alleviating
Agents in Developing Hen Eggs With Special Emphasis on Bidrin," Biochem.
Pharmacol., 18(2):373-392 (1969).
121
-------
Ross, E., and M. Sherman,."The Effect of Selected Insecticides on Growth
and Egg Production When Administered Continuously in the Feed," Poult.
Sci.. 39:1023-1311 (1960).
Sauter, E. A., and E. E. Steele, "The Effect of Low Level Pesticide
Feeding on the Fertility and Hatchability of Chicken Eggs," Poult. Sci.,
51:71-76 (1972).
Schwartz, C. C., J. G. Nagy, and C. L. Streeter, J. Anim. Sci., 37(3):
821-826 (1973).
Shah, A. H., and F. E. Guthrie, "Penetration of Insecticides Through the
Isolated Midgut of Insects and Mammals," Comp. Gen. Pharmacol., 1:391-
399 (1970).
Shah, P. V., and F. E. Guthrie, "Pentration of Insecticides Through Iso-
lated Sections of the Mouse Digestive System: Effects of Age and Region
of Intestine," Toxicol. Appl. Pharmacol., 25:621-624 (1973).
Sherman, M., and E. Ross, "Toxicity of House Fly Larvae to Insecticides
Administered as Single Oral Dosages to Chicks," J. Econ. Entomol.,
52(4):719-723 (1959).
Spiller, D., "A Digest of Available Information on the Insecticide Mala-
thion," Adv. Pest Control Res.. Vol. IV, Interscience Publishers (1961).
Spynu, E. I., "The Effect of Some Organophosphorus Insecticides in the
Higher Nervous Activities and on the Cholinesterase Activity," The
Chemistry and Application of Organophosphorus Compounds, Edited by
Acad. Sci., USSR, Moscow (1957), quoted by Medved et al. (1964).
Stevens, J. T., and F. E. Greene, "Response of the Mixed Function Oxi-
dase System of Rat Hepatic Microsomes to Parathion and Malathion and
Their Oxygenated Analogs," Life Sci., 13:1677-1691 (1973).
Stevens, J. T., R. E. Stitzel, and J. J. McPhillips, "Effects of Anti-
cholinesterase Insecticides of Hepatic Microsomal Metabolism," J^
Pharmacol. Exp. Ther.. 181(3):576-583 (1972).
Tuthill, J. W. G., "Toxic Hazards: Malathion Poisoning," N. Engl. J.
Med., 258:1018-1019 (1958).
122
-------
Upshall, D. G., J. Roger, and J. E. Casida, "Biochemical Studies on
the Teratogenic Action of Bidrin and Other Neuroactive Agents in
Developing Hen Eggs," Biochem. Pharmacol., 17:1529-1542 (1968).
Varnai, L., "Pathology of Malathion Poisoning," Orv. Hetil., 112:1651-
1653 (1971).
Walker, N. E., "Distribution of Chemicals Injected into Fertile Eggs and
Its Effect upon Apparent Toxicity," Toxicol. Appl. Pharmacol., 10:290-
299 (1967).
Walker, N. E., "Use of Yolk-Chemical Mixtures to Replace Hen Egg Yolk in
Toxicity and Teratogenicity Studies," Toxicol. Appl. Pharmacol., 12:
94-104 (1968).
Walker, N. E., "The Effect of Malathion and Malaoxon on Esterases and
Gross Development of the Chick Embryo," Toxicol. Appl. Pharmacol., 19:
590-601 (1971).
Walters, M. N. I., "Malathion Intoxication," Med. J. Aust., 1:876-877
(1957).
Watanabe, S., "Detection of Organophosphate Pesticides in Blood Serum from
Patients Suspected of Acute and Chronic Pesticides Poisonings and Its
Clinical Significance," Tohoku J. Exp. Med.. 107(3):301-302 (1972).
Wilber, C. G., "New Insecticides. Toxicity, Hazards, and Therapy,"
Iowa State Univ. Vet.. 23:21-23 (1960).
Wilson, B. W., and N. E. Walker, "Toxicity of Malathion and Mercaptosuccinate
to Growth of Chick Embryo Cells In Vitro," Proc. Soc. Exp. Biol. Med..,
121(4)=1260-1264 (1966).
World Health Organization, "Toxic Hazards of Pesticides to Man," Technical
Report, Series No. 114 (1956).
Wolfe, H. R., W. F- Durham, and J. F. Armstrong, "Exposure of Workers to
Pesticides," Arch. Environ. Health, 14:622-633 (1967).
Yip, G., and J. W. Cook, "Malathionase. III. Substrate Specificity
Studies," J. Assoc. Off. Agric. Chem.. 42:405-407 (1959).
123
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SUBPART II. C. FATE AND SIGNIFICANCE IN THE ENVIRONMENT
CONTENTS
Page
Effect on Aquatic Species 126
Fish 126
Toxicity . 126
Field Studies 126
Other Aquatic Biota 135
Laboratory Studies 135
Field Studies 144
Effects on Wildlife 147
Laboratory Studies 147
Field Studies 147
Effects on Beneficial Insects .... ........ 150
Bees 150
Parasites and Predators 153
Interactions with Lower Terrestrial Organisms 157
Reviews ......... 157
Laboratory and Field Studies 157
Residues in Soil 161
Laboratory Studies 161
Field and Combined Field-Laboratory Studies 164
Monitoring Studies • 164
Residues in Water 167
Reviews 167
Laboratory and Field Studies 167
Monitoring Data 170
124
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CONTENTS (Continued)
Page
Residues in Air 172
Residues in Nontarget Plants 172
Bioaccumulation, Biomagnification 173
Environmental Transport Mechanisms 173
References 175
125
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This section contains data on the environmental effects of malathion,
including effects on aquatic species, wildlife, and beneficial insects,
interactions with lower terrestrial organisms and effects on residues in
soil, water and air. The section summarizes rather than interprets data
reviewed.
Effect on Aquatic Species
Fish -
Toxicity - The acute toxicity of malathion to various species of
fish is shown in Table 19. (Scientific names of fish species are given
in Table 20.) As shown, the toxicity of malathion to fish varies as to
the species and as to the way toxicity is expressed. This toxicity
ranges from a high with bluegill to a low with mummichog. It appears
that young bluegill are more susceptible to malathion than older bluegill
(Pickering et al., 1962-i/).
Available data on the subacute and chronic toxicity of malathion
to fish are summarized in Table 21.
Signs of malathion poisoning in fish consisted of uncoordinated
movements, swimming on sides* air searching, and finally cessation of
gill movement (Murphy, 1967—'). Death was preceded by an involuntary
extension of the pectoral fins. A reddish discoloration due to hem-
orrhaging in the muscle beneath the dorsal fin was evident. Brain
cholinesterase depression to one-third of the control value was found
at toxicant concentrations considered to be safe. Malathion also
caused high percentages of spinal deformities at 7.4 ppb. (Eaton,
19701/).
Field studies - Kennedy and Walsh (1970)— studied the toxicity
of malathion to the bluegill (Lepomis macrochirus) and the channel cat-
fish (Ictalurus punctatus) in ponds which were treated four times at
the rate of 0.002 or 0.02 ppm over an 11-week period. Fish mortality
ranged from 8 to 44%, but was not correlated with the treatment levels.
I/ Pickering, Q. H., C. Henderson, and A. E. Lemke, "The Toxicity of
Organic Phosphorus Insecticides to Different Species of Warmwater
Fishes," Trans. Am. Fish Soc., 91(2):175-184 (1962).
2J Murphy, S. D., "Malathion Inhibition of Esterases as a Determinant
of Malathion Toxicity," J. Pharmacol. Exp. Ther., 156:352-365
(1967).
3/ Eaton, J. G., "Chronic Malathion Toxicity to the Bluegill (Lepomis
macrochirus Rafinesque)," Water Res., 4:673-684 (1970).
4/ Kennedy, H. D., and D. F. Walsh, "Effects of Malathion on Two Warm-
water Fishes and Aquatic Invertebrates in Ponds," U.S. Bureau of
Sport Fisheries and Wildlife Tech. Paper No. 55, 13 pages (1970).
126
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Table 19. ACUTE TOXICITY OF MALATH10N TO FISH
Fish tested
Fathead minnow
Fathead minnow
Fathead minnow
Fathead minnow
Fathead minnow
Fathead minnow
Fathead minnow
Fathead minnow
Fathead minnow
Fathead minnow
Bluegill
Bluegill
Bluegill
Bluegill - small
Bluegill - small
Bluegill - small
Bluegill - large
Bluegill - large
Bluegill - large
Bluegill
Bluegill
Bluegill
Bluegill
Bluegill
Carp
Carp
Rainbow trout
Rainbow trout
Rainbow trout
Rainbow trout
Rainbow trout
Brook trout
Green sunfish
Green sunfish
Green sunfish
Red ear sunfish
Largemouth bass
Largemouth bass
Largemouth bass
Largemouth bass
Tilapia
Tilapia
Tilapia
Black bullhead
Striped bass
Striped bass
Striped bass
Goldfish
Goldfish
Goldfish
Goldfish
Guppy
Guppy
Guppy
Exposure
time
(hr)
96
96
24
48
96
24
48
96
96
96
24
48
96
24
48
96
24
48
96
24
48
96
96
96
48
48
96
24
48
96
24
48
24
48
96
96
24
48
96
96
48
48
48
96
24
48
96
96
24
. 48
96
24
48
96
Toxicity
calculation
T^
TLflf
TLm
TLm
TLm
TL
TL^
TL50
LC50
TL
TL
TL
Ul
TC
111
TLm
TL
Si™
TLm
TLm
TL50
"•50
LCIOO
TL-Q
17% mortality
17% mortality
26% mortality
100% mortality
LCen
TLm
TL_
Ul
IL
TLm
TLm
iBI
TL50
T4
^lOO
TL5Q
LC50
LC50
LC50
TL50
TL
m
TL
m
TL
TLm
TL™
m
Toxicity
measured
(ppm)
9
23.5
26.0
24.0
23.0
25.0*
25.0*
25.0*
8.65
12.5
0.14
0.12
0.090
0.60+
0.55 +
o.sst
1.7t
1.3t
1.2+
0.19*
0.11*
0.088*
0.103
0.11
10.0
13.5
0.170
1
1
1
10
0.2
1.2t
0.70+
0.60+
0.17
0.42 +
0.28 +
0.25 +
0.285
5
8.3
10.0
12.9
0.79
0.46
0.24
10.7
0.79*
0.79*
0.79*
0.93
0.88
0.84
References
a/
b/
c/
c/
c/
c/
c/
c/
d/
e/, f/
c/
c/
c/
c/
c/
c/
c/
£/
c/
'c/
c/
c/
i/
&/
h/
h/
d/
ll
if
i/
i/
11
c/
c/
c/
d/
£/
c/
c/
d/
i/
h/
h/
I/
y
y
y
d/
" c/
c/
c/
c/
c/
c/
127
-------
Table 19. (Concluded)
Fish tested
Channel catfish
Channel catfish
Brown trout
Coho salmon
Yellow perch
Mummichog
Harlequin fish
Cirrhina mrigola
Cirrhina mrigola
Labeo fimbreatus
Labeo fimbreatus
Labeo rohita
Labeo rohita
Danio sp.
Danio sp.
Walleye pike
Walleye pike
Exposure
time
(hr)
96
96
96
96
96
96
24
48
48
48
48
48
48
48.
48
24
24
Toxicity
calculation
TL50
TL50
TL50
TL
TLi
'50
'50
LC50
LC
'50
TL«
LC100
TLm
LC100
TLm
LC
TL
100
m
LC100
07. mortality
957. mortality
Toxicity
measured
(ppm)
8.97
0.76
0.200
0.101
0.263
70
10
7
15
8.5
12.0
8.0
10.0
13.5
14.0
0.74
1.84
References
I/
I/
m/
y
y
y
y
y
y
y
y
y
n/
* Emulsifiable concentrate 577..
t Emulsifiable concentrate 207..
a/ Mount, D. I., and C. E. Stephan, "A Method for Establishing Acceptable Toxicant
Limits for Fish—Malathion and the Butoxyethanol Ester of 2,4-D," Trans. Am.
Fish. Soc.. 96:185-193 (1967).
b/ Bender, M. E., "Toxicity of the Hydrolysis and Breakdown Products of Malathion
to the Fathead Minnow (Pimephales promelas)." Water Res.. 3(8) .-571-582 (1969).
£/ Pickering et al.,_OD_. cit. (1962).
d_/ Macek, K. J., and W. A. McAllister, "Insecticide Susceptibility of Some Common
Fish Family Representatives," Trans. Am. Fish. Soc.. 99(1):20-27 (1970).
e/ Katz, M., "Acute Toxicity of Some Organic Insecticides to Three Species of Sal-
monids and to the Threespine Stickleback," Trans. Am. Fish. Soc.. 9t)(3):264-
268 (1961).
fj Pimentel, D., "Ecological Effects of Pesticides on Nontarget Species," Execu-
tive Office of the President, Office of Science and Technology, U.S. Govern-
ment Printing Office, Washington, D.C. (1971).
g/ Kennedy and Walsh, op. cit. (1970).
h/ Sreenivasan, A., and G. K. Swaminathan, "Toxicity of Six Organophosphorus Insec-
ticides to Fish," Gurr. Sci.. 36:397-398 (1967).
if Lewallen, L. L., and W. H. Wilder, "Toxicity of Certain Organophosphorus and
Carbamate Insecticides to Rainbow Trout," Mosquito News, 22(4):369-372 (1962).
j/ Sreenivasan, A., and R. R. Saundar, "Toxicity of Malathion and Parathion to
Fish," Symposium on Pesticides. Mysore. India. 1961. pp. 316-318 (1968).
k/ Wellborn, T. L., "Toxicity of Some Compounds to Striped Bass Fingerlings," Prog.
Fish Cult.. 33(l):32-36 (1971).
I/ Eisler, R., Jr., "Factors Affecting Pesticide-Induced Toxicity in an Estuarine
Fish," U.S. Bureau of Sport Fisheries and Wildlife Tech. Paper No. 45, pp. 1-20
(1970).
m/ Alabaster, J. S., "Survival of Fish in 164 Herbicides, Insecticides, Fungicides,
Wetting Agents and Miscellaneous Substances," Int. Pest. Control. ll(2):29-35
(1969).
n/ Hilsenhoff, W. L., "Toxicity of Granular Malathion to Walleyed Pike Fingerlings,"
Mosquito News. 22:14-15 (1962).
128
-------
Table 20. COMMON AND SCIENTIFIC NAMES OF FISH USED IN
CONTROLLED TOXICITY TESTS WITH MALATHION
Common name
Scientific name
Fathead minnow
Bluegill
Carp
Rainbow trout
Brook trout
Green sunfish
Pumpkinseed
Largemouth bass
Mummichog
Tilapia
Striped mullet
Golden shiner
Black bullhead
Mosquito fish
Rice fish
Goldfish
Guppy
Yellow perch
Walleye pike
Channel catfish
Brown trout
Coho salmon
Striped bass
Hawkfish
Harlequin fish
Red ear sunfish
Striped bass
Hawkfish
Harlequin fish
Pimephales promelas
Lepomis macrochirus
Cyprinus carpio
Salmo gairdneri
Salvelinus fontinalis
Lepomis cyanellus
Lepomis gibbosus
Micropterus salmoides
Fundulus heteroclitus
Tilapia aurea
Mugil cephalus
Notemigonus crysoleusas
Ictalurus melas
Gambusia affinis
Oryzias latipes
Carassius auratus
Lebistes reticulatus
Perca flavescens
Stizostedian vitreum vitreum
Ictalurus punctatus
Salmo trutta
Oncorhynchus kisutch
Morone saxatilis
Cirrhina mrigola
Rasbor heteromorpha
Lepomis microlophus
Morone saxatilis
Cirrhina mrigola
Rasbor heteromorpha
129
-------
Table 21. SUBACUTE AND CHRONIC TOXICITY OF MALATHION TO FISH
Fish tested
Bluegill
Bluegill
Mummichog
Fathead minnow
Fathead minnow
a/ Eaton , op .
b_/ Eisler, op.
c/ Mount and S
Exposure
time
(days)
7
11
10
4 months
4 months
cit. (1970).
cit. (1970).
tephan, op. cit
Toxicity
Toxicity measured
calculation (ppm)
LTC 0.079
LTC 0.085
LC5Q 70.0
TLjjj - 96 hr 9
Maximum 0.2-0.58
acceptable
cone.
.. (1967).
References
sJ
£/
y
£/
£/
130
-------
There were no differences in fish growth or microhematocrit values be-
tween the fishes in the treated and untreated ponds. No acute or
chronic pathology developed, and no significant depression of brain
cholinesterase was observed. Bluegills spawned twice during the study
period.
A number of authors investigated the toxicity of malathion to estu-
arine fish, with a view to its use for the control of mosquito larvae in
salt marshes. Darsie and Corriden (1959)i/ performed a series of field
tests to ascertain the toxicity of malathion to killifish (family
Cyprinodontidae) in tidal marshes in Delaware. Groups of 25 fish each
were exposed in metal tubs containing 7 gal. of habitat water. Mala-
thion was applied at the rate of 0.5 Ib Al/acre aerially to simulate
practical mosquito control procedures. Among fish exposed for 4 hr,
26% died, 42% were sublethally poisoned, and 31% were unaffected. The
fate of the moribund fish was followed for 64 hr after treatment. Of
these, 667» recovered, 8% still showed symptoms at the end of the obser-
vation period, and 26% died.
Westman and Compton (I960)—' reported that the exposure of salt
marsh killifishes (Cyprinodon variegatus) to malathion at a concentra-
tion of 0.1 ppm resulted in 30% mortality, and approximately 80% crippled
fishes. Lower temperatures delayed mortality and crippling; the higher
the temperature, the quicker the effect. The authors point out that in
nature, crippled fish usually are victims of early predation.
Joseph et al. (1972)—' studied the effects of ultra-low-volume (ULV)
field applications of malathion to goldfish. Malathion was applied at
the recommended rate, 1.5 fl oz/min, and at 10 times that rate. After
20 separate applications within a 34-day period, the exposed fish did
not exhibit any detectable neurotoxic symptoms.
I/ Darsie, R. F., Jr., and F. E. Corriden, "The Toxicity of Malathion
to Killifish (Cyprinodontidae) in Delaware," J. Econ. Entomol.,
52:696-700 (1959).
2/ Westman, J. R., and K. Compton, "Responses of Salt Marsh Killifishes
to Certain Environmental Changes and to Malathion,11 Proc. New
Jersey Mosquito Extermination Assoc., 47:116-123 (1960).
3_/ Joseph, S. R., J. Mallack, and L. F. George, "Field Applications of
Ultra-Low-Volume Malathion to Three Animal Species," Mosquito
News. 32:504 (1972).
131
-------
Coppage and Duke (1.971)1.' monitored the effects of malathion
sprayed by aircraft- for mosquito control purposes over two Louisiana
lakes. Three species of fish (spot, Leiostomus xanthurus; Atlantic
croaker, Micropogon undulatus; and striped mullet, Mugil cephalus)
were collected and assayed for brain acetylcholinesterase (AChE) activ-
ity. Fish from the lake that was treated at the rate of 3 oz of mala-
thion AI per acre exhibited significant AChE inhibition, ranging from
about 20 to 807o. Fish kills were reported during the spraying period,
and moribund fish were collected. Malathion at the same rate was also
applied around a second lake, but in this case not over open waters.
Only a few fish collected from this lake were found to have significant
AChE inhibition.
Tagatz et al. (1974)A' investigated the effects on sheepshead minnows
(Cyprinodon variegatus) of malathion sprayed on a salt marsh near Fensacola
Beach, Florida. Malathion was applied as a thermal fog at 6 oz Al/acre
and as a ULV aerosol spray at 0.64 fl oz/acre three times in succession,
typical of usual mosquito control operations. There was no fish mortality,
and no brain AChE depression was observed in confined fish exposed to one
or more treatments.
In 1966, malathion was used for the control of grasshoppers on
Indian reservations in Montana and Wyoming, and in the Dixie National
Forest, Utah. Morton (1966)1' reported that no dead fish were observed
in a stream or in live-boxes following the aerial application of mala-
thion (dosage rate not specified) on the Crow Indian Reservation,
I/ Coppage, D. L., and T. W. Duke, "Effects of Pesticides in Estuaries
Along the Gulf and Southeast Atlantic Coasts," Proc. of the 2nd
Gulf Coast Conference on Mosquito Suppression and Wildlife Man-
agement , pp. 26-30 (1971).
2_/ Tagatz, M. E., P. W. Borthwick, G. H. Cook, and D. L. Coppage,
"Studies on Effects of Ground Applications of Malathion on Salt-
Marsh Environments in Northwestern Florida," unpublished manu-
script, submitted to Mosquito News, 16 pages (1974).
3_/ Morton, W. M., "Malathion Grasshopper Control Project on the Crow
Indian Reservation in Yellowstone and Big Horn Counties, Montana,"
U.S. Department of the Interior, Bureau of Sport Fisheries and
Wildlife, Pesticide Surveillance Program, Special Report, 10 pages,
8 figures, 4 tables (1966).
132
-------
Montana. Henderson (1967a)i' reported "minimal effects on fish" follow-
ing aerial application of technical malathion at the rate of 7.9 fl oz/
acre to 37,440 acres on the Wind River Indian Reservation, Wyoming.
Henderson (1967b)2/ also monitored the effects of the application of
malathion at the rate of about 8 fl oz/acre to 4,300 acres in the Dixie
National Forest, Utah. In this case, about 80 dead brook trout ranging in
size from 3 to 14 in. were found. Most of the fish mortality occurred
in areas where overlapping of spray swaths was observed. Brain AChE
levels in samples of these dead fish were near zero. All fish confined
in live-boxes in the same area survived the treatment. Henderson sug-
gests that wild unconfined fish obtained additional exposure to the
insecticide by feeding on dead insects.
Kerswill and Edwards (1967)^.' monitored the survival of young
Atlantic salmon and eastern brook trout sprayed with malathion for
budworm control. The trout, found in New Brunswick, Connecticut
streams, were studied in their natural habitat and in caged environments.
Malathion at 0.8 Ib/acre had no apparent short-term effects on salmon
parr, but killed many under a year old.
Giles (1970)—' studied the effects on the faunal ecology of an
aerial application of malathion at 0.7 Ib Al/acre to a 19.8-acre water-
shed covered by deciduous forest in Ohio. Fishes and crayfishes which
were sensitive to malathion in laboratory tests were unaffected in the
stream environment.
I/ Henderson, C., "Little Wind Grasshopper Control Project, Wind River
Indian Reservation, Wyoming," U.S. Department of the Interior,
Bureau of Sport Fisheries and Wildlife, Pesticide Surveillance
Program, Special Report, 20 pages, 9 figures (1967a).
2/ Henderson, C., "Podunk Grasshopper Control Project, Dixie National
Forest, Utah," U.S. Department of the Interior, Bureau of Sport
Fisheries and Wildlife, Pesticide Surveillance Program, Special
Report, 24 pages, 9 figures (1967b).
3/ Kerswill, C. J., and H. E. Edwards, "Fish Losses After Forest Spray-
ing with Insecticides in New Brunswick, 1952-1962, as Shown by
Caged Specimens and Other Observations," Fish Res. Board Can. J.,
24(4):709-729 (1967).
4/ Giles, R. H., Jr., "The Ecology of a Small Forested Watershed
Treated with the Insecticide Malathion--"S," Wildlife Monographs,
No. 24, 8L pages (1970).
133
-------
Shea (1970)- reported that an estimated 349,000 fish were killed
in a creek near Troy, Missouri, as a result of careless dumping of a
mixture of chlordane and malathion in xylene on the ground about 100 yd
from the creek. However, no data are provided that would allow separa-
tion of the relative contribution of malathion in this episode, nor on
the concentrations of malathion to which the fish were exposed.
Hansen (1969)-/ and Hansen et al. (1972)-/ studied the capacity of
fish to avoid pesticides, including malathion. Sheepshead minnows (C.
variegatus) did not avoid the test concentrations of malathion, while
they were able to avoid several other pesticides tested in the same
manner. Mosquitofish (Gambusia affinis) showed a real, but not pro-
nounced, ability to avoid water contaminated with malathion (and sev-
eral other insecticides).
Wilson (1966)—' investigated the toxicity of malathion and several
of its metabolites to the fathead minnow (Pimephales promelas). The
following 96-hr LCjg values (ppm) were obtained: malathion, 14; diethyl
succinate, 18; malic acid, 25; mercapto succinic acid, 30; diethyl fuma-
rate, 38; diethyl maleate, 41; dimethyl phosphite, 225; dimethyl phos-
phate, 250. By contrast, Bender (1969) reported that the "basic hydro-
lysis product" of malathion, diethyl fumarate, was more toxic than mala-
thion itself to fathead minnows. Interestingly, this author found a
pronounced synergistic effect between malathion and its two basic hydro-
lyses products. Continuous exposure (14 days) decreased the mean lethal
time concentration of malathion as well as of its hydrolysis products.
Only one report was found on the toxicity of malathion to fishes.
Liska (1971).5-/ reported the toxicity threshold for (unspecified) fishes
for malathion at 0.2 mg/liter.
I/ Shea, K. P., "Dead Stream," Environment, 12(6):12-15 (1970).
2_/ Hansen, D. J., "Avoidance of Pesticides by Untrained Sheepshead
Minnows," Trans. Am. Fish. Soc.. 98(3):426-429 (1969).
3_/ Hansen, D. J., E. Matthews, S. L. Nail, and D. P. Dumas, "Avoid-
ance of Pesticides by Untrained Mosquitofish, Gambusia affinis,"
Bull. Environ. Contam. Toxicol., 8(1):46-51 (1972).
4_/ Wilson, B. R., "Fate of Pesticides in the Environment - A Progress
Report," Trans. New York. N. Y. Acad. Sci., 28:694-705 (1966).
Quoted from Pimentel (1971).
5_/ Liska, D., "Sanitary-Hygienic and Toxicological Problems of Pesticide
Residues in Some Spheres of the Environment," Lek. Obz., 29(1):
11-15 (1971).
134
-------
The data reviewed indicates that malathion is highly toxic to
fish, and that the potential for damage to fish populations exists when
malathion is used at insecticidally effective rates of application. In
view of the large-scale use of malathion (including uses over or near
aquatic environments) and the somewhat contradictory reports on the fish
toxicity of malathion degradation products, there appears to be a need
for more information on the toxicity of malathion degradation products
to fish (as well as to other nontarget organisms), and on the persis-
tence and fate of these degradation products in the aquatic (and terres-
trial) environment.
Other Aquatic Biota - For purposes of this review, "other aquatic biota"
are defined to include primary producers (phytoplankton, attached algae,
moss, and vascular plants); consumers (protozoa, rotifers, and Crustacea);
benthic invertebrates (annelids, insects, Crustacea, and mollusca); and
decomposers (fungi and bacteria).
Laboratory studies - In static bioassay tests on the toxicity of malathion
to aquatic organisms, the following 48-hr TI^ values were found: Stonefly,
Pteronarcys badia (6); water flea, Daphnia pulex (1.8); brook trout,
Salvelinus fontinalis (19.5); and for amphipod. Gammarus lacustris (1.8).i/
Data on the toxicity of malathion to three species of Daphnia and to
Simocephalus serrulatus is presented in Table 22. The EC$Q (immobilization)
values of malathion to the zooplankton species ranged from 0.2 to 6.2 ppb,
depending upon test species, temperature, and exposure time.
Data on the toxicity of malathion to benthic invertebrates is presented
in Table 23. The LCjQ values of malathion to several species of stoneflies,
caddisflies, and mayflies and to one amphipod species, vary over an even
wider range, again depending upon the test species and the experimental
conditions.
I/ Federal Water Pollution Control Administration, Water Quality Criteria;
Report of the National Technical Advisory Committee, p. 37 (1968)
135
-------
Table 22. EC50 (IMMOBILIZATION) VALUES (ppb)
OF MALATHION TO ZOOPLANKTON
Time £059
Species Temperature (hr) ppb References
Daphnia pulex 21°C 48 2 £/
60°F 48 1.8 >./
60°F 48 1.8 SJ
Daphnia magna 68°F 24 0.9 £/
68 "F 50 a. 9 y
20°C 50 0.9 &J
Daphnia 78°F 64 0.2 -*
carinata
Simocephalus 60°F 48 3.5 ' V
serrulatus 70°F 48 6.2 , ]>/
a/ Cope, 0. B., "Contamination of the Freshwater Ecosystem by Pesticides," J. Appl. Ecol. .
"~ 3(Suppl):33-44 (1966). In: Li and Fleck (1972).
b/ Sanders, H. 0., and 0. B. Cope, "Toxicities of Several Pesticides to Two Species
~ of Cladocerans," Trans. Am. Fish. Soc.. 95(2):165-169 (1966).
c/ Federal Water Pollution Control Administration, "Wa'ter Quality Criteria," Report
of the National Technical Advisory Committee, p. 37 (1968).
d/ Anderson, B. G., "The Toxicity of Organic Insecticides to Daphnia." in: Transactions
of the Second Seminar on Biological Problems in Water Pollution. Cincinnati, Ohio,
U.S. Public Health Service, pp. 94-95 (1959). In: Li and Fleck (1972).
e/ Matida, Y., and N. Kawasaki, "Study on the Toxicity of Agricultural Control Chemicals
in Relation to Freshwater Fisheries Management," No. 2, Toxicity of Agricultural
Insecticides to Daphnia carinata. King. Bull. Freshwater Fish. Res. Lab.. Tokyo,
8:1-6 (1958). In: Li and Fleck (1972).
Source: Li, M., and R. A. Fleck, "The Effects of Agricultural Pesticides in the Aquatic
Environment, Irrigated Croplands, San Joaquin Valley," Pesticide Study Series
6. Environmental Protection Agency, Office of Water Programs, Applied Tech-
nology Division, Rural Waste Branch TS-00-72-05, 268 pages (1972).
136
-------
Table 23. LC5Q VALUES (ppb) OF MALATHION
TO BENTHIC INVERTEBRATES
Species
Stoneflles
Pteronarcys
californtca
Acroneurla
pacif lea
Pteronarcella
badta
Classenta
sabulosa
Caddisflies
Arctopsvche
grandis
Hydropsvche
caltfornica
Mayflies
Ephemerella
grandis
Temperature
15.5'C
15.5°C
21 "C
11-12°C
11-12°C
11-12°C
15.5°C
12.8'C
12.8°C
12.8°C
12.8°C
12.8°C
12.8*C
11-12'C
11-12°C
11-12"C
12.8'C
12.8*C
12.8'C
12.8°C
12.8°C
12.8°C
15.5°C
15.5"C
48-50°F
15.5°C
15.5eC
15.5°C
15.5°C
51-54°F
51-54°F
48-50'F
Time (hr)
(* = days)
24
48
48
48
72
96
96
5*
10*
15*
20*
25*
30*
48
72
96
5*
10*
15*
20*
25*
30*
24
48
48
96
24
48
96
96
96
96
LC50
ppb
35.0
20.0
21.0
180.0
72.5
50.0
10.0
45.0
24.0
15.5
8.8
12.0
16.0
7.0
7.7
5.1
3.3
3.2
2.4
0.78
10.0
60.0
6.0
1.1
13.0
6.0
2.8
32.0
22.5
100.0
References
a/
a/
b/
±1
d/
d/, e/
a/
f/
11
f/
LI
f/
f/
d/
d/
I/. £/
fj
{/
tl
LI
tl
LI
a/
a/
£/
S.I
a/
£/
«/
£/
e/
e/
137
-------
Table 23. (Continued)
Amphlpods
Gamma rus
lacustris
Temperature
21 "C
70'F
70"F
60*F
70°F
59 *F
Time (hr)
(* - days)
48
24
48
48
48
96
LC50
Ppb
6.0
3.8
1.8
1.8
1.0
1.62
References
£/
&/
c/
&/
e/
£/ Sanders, H. 0., and 0. B. Cope, "The Relative Toxieltles of Several Pesticides to Naiads of Three
Species of Stoneflies," Limnol. Oceanog.. 13(1):112-117 (1968).
b/ Cope, op. ctt. (1966).
£/ FWPCA, op_. ci±. (1968).
~&l Jensen, L. D., and A. R. Gaufin, "Effects of Ten Organic Insecticides on Two Species of Stonefly Naiads,"
Trans. Anu Fish. Joe... 93:27-34 (1964a) . In: Li and Fleck (1972) .
£/ Gaufin, A. R., L. D. Jensen, A. V. Hebeker, T. Nelson, and R. W. Teel, "The Toxicity of Ten Organic
Insecticides to Various Aquatic Invertebrates," Water Sewage .Works. 12-. 276-279 (1965^. In: ti and
Fleck (1972).
f/ Jensen, L. D., and A. R. Gaufin, "Long-Term Effects of Organic Insecticides on Two Species of Stonefly
Naiads." Trans. Am. Fish. Soc.. 93:357-363 (1964b). In: Li and Fleck (1972).
£/ Sanders, H. 0., "Toxicity of Pesticides to the Crustacean Gammarus lacustris," U.S. Department
of the Interior, Fish and Wildlife Service, Technical Paper No. 25, p. 18 (1969).
Source: Li and Fleck, op. cit. (1972).
138
-------
Ware and Roan (1971)-/ reviewed the literature on the interactions
of pesticides with aquatic microorganisms and plankton. A brief sec-
tion dealing with organophosphate insecticides contains little specific
information on malathion.
Moore (1970)—/ and Poorman (1973)=-' investigated the effects of
malathion on growth and survival of the photosynthetic microorganisms
Euglena gracilis. In Moore's tests, malathion inhibited the growth
rate of the organism only at the highest rate tested, 7.25 ppm. Poorman
found that malathion at 50 and 100 ppm depressed the growth rate of E.
gracilis only to a small extent during a 24-hr exposure. When the or-
ganism was exposed to malathion for 7 days, there was considerable
growth stimulation as compared to untreated controls. The results
indicate that malathion is not likely to adversely affect E. gracilis
under field conditions. Lazaroff (1967)A' also found that malathion
did not adversely affect freshwater algae. He employed an assay system
based on the inhibition of motility of E_. gracilis.
Lewis et al. (1974),I/ Paris et al. (1974) £l and Paris and Lewis
(1974)2J recently reported on the interactions between malathion and a
water fungus (Aspergillus oryzae) and a heterogeneous population of
I/ Ware, G. W., and C. C. Roan, "Interaction of Pesticides with Aquatic
Microorganisms and Plankton," Residue Rev., 33:15-45 (1971).
2/ Moore, R. B., "Effects of Pesticides on Growth and Survival of Euglena
gracilis Z.," Bull. Environ. Contain. Toxicol., 5(3):226-230 (1970).
3/ Poorman, A. E., "Effects of Pesticides on Euglena gracilis. I.
Growth Studies,"Bull. Environ. Contam. Toxicol., 10(1):25-28 (1973).
4/ Lazaroff, N., "Algal Response to Pesticide Pollutants," Bacteriol.
Proc., CI:48 (1967).
5/ Lewis, D. L., D. F. Paris, and G. L. Baughman, "Uptake and Transfor-
mation of Malathion by a Fungus, Aspergillus oryzae, Isolated from
a Freshwater Pond," submitted to Appl. Microbiol. (1974).
fj Paris, D. F., D. L. Lewis, and G. L. Baughman, "Rates of Degradation
of Malathion," unpublished manuscript, submitted to Environ. Sci.
Techno1. (1974).
TJ Paris, D. F., and D. L. Lewis, "Rates and Products of Degradation of
Malathion by Bacteria and Fungi from Aquatic Systems," presented at
the 167th National Meeting of the American Chemical Society, Divi-
sion of Pesticide Chemistry, Los Angeles, California (1974).
139
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aquatic bacteria. A. orygae was isolated from a local pond. Malathion
was rapidly removed from water by the fungus, and approximately 97% of
the malathion quantity removed was converted to |3-malathion monoacid.
However, no fungal growth was observed during the experiment. A bac-
terial culture was isolated from river water and enriched by a culture
technique. Members of the bacterial population included Flavobacterium
meningosepticum, Xanthomonas sp., Comamonas terrigeri, and Pseudomonas
cepacia. This population was capable of utilizing malathion as the
sole carbon source. The major metabolite identified was again
P-malathion monoacid. However, the malathion uptake speed per unit dry
weight of cell material for equivalent malathion concentrations was
approximately 5,000 times faster with the bacteria than with the fungus.
Several investigators have dealt with the effects of malathion on
microorganisms from waste treatment systems. Steelman et al. (1967)17
determined the toxicity of malathion and several other insecticides
applied at concentrations ranging from 0.1 to 5.0% to bacterial popula-
tions in waste disposal lagoons. Waste disposal lagoon water was obtained
from the Louisiana State University Poultry Farm. The LD50 of malathion
to the (unidentified) bacteria in the system after 24-hr exposure was
0.4%, the LD90 was 2.35%. Some of the other insecticides tested under
the same conditions were more, others were less toxic to the bacteria.
When the lagoon water was treated with malathion at 1 ppm, bacterial
mortality was 0.83% after 24 hr, zero after 48 hr. The authors conclude
that malathion at 1 ppm (the concentration that might be used to control
mosquito breeding in waste disposal lagoons) would not cause functional
disruption of the lagoon process.
Christie (1969)—/ treated algal suspensions from a waste stabili-
zation pond with malathion at the rate of 100 ppm. At this rate, algal
counts were reduced to less than 45% of untreated controls. At a con-
centration of less than 100 ppm, malathion did not inhibit Chlorella
pyrenoidosa cultures. After 7 days contact of a Chlorella culture with
malathion, 67% of the insecticide was recovered. The author believes
I/ Steelman, C. D., A. R. Colmer, L. Cabes, H. T. Barr, and B. A. Tower,
"Relative Toxicity of Selected Insecticides to Bacterial Populations
in Waste Disposal Lagoons." J. Econ. Entomol.. 60(2) :467-468 (1967).
2_/ Christie, A. E., "Effects of Insecticides on Algae," Water Sewage
Works, 116(5):172-176 (1969).
140
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that malathion at these concentrations would temporarily interfere with
the efficiency of oxidation ponds, but that it would be broken down by
chemical and metabolic reactions.
Halvorson et al. (1971)i/ developed a procedure to test the bio-
degradability of insecticides by incubating the chemical in a resting-
cell suspension of bacteria from a sewage lagoon. There were 50 ppm
of malathion added to a cell suspension containing about 400 million
bacterial cells per milliliter. These suspensions were then incubated
for up to 8 days under aerobic and anaerobic conditions. Malathion (and
other organophosphates) was quickly degraded under these conditions,
while several persistent chlorinated hydrocarbon insecticides were
metabolized poorly or not at all.
Randall et al. (1967) —/ studied the biodegradation of malathion in
activated sludge. When shock loadings of malathion were applied to an
activated sludge microbial system, an immediate, nonrecoverable uptake
of 20% of the chemical was observed. Microbial systems could assimilate
single shock loadings of 100 mg/liter without apparent effect. Such
systems can effectively assimilate repeated loadings over prolonged
periods of time when sufficient nutrients are present. The toxicity
of malathion to mixed aquatic biota depended on the organic material
present. A low ratio of malathion to microorganisms stimulated mi-
crobial activity, whereas large ratios (1:5 or greater) inhibited res-
piration. Microbial systems acclimated to malathion had a greater re-
sistance to its toxic effects and were more efficient in utilizing mala-
thion as an energy source. Metabolism was greatly increased when no
other substrate was present. The authors conclude that the danger of
I/ Halvorson, H. M., Jr., M. Ishaque, J. Solomon, Jr., and 0. W.
Grussendorf, Jr., "A Biodegradability Test for Insecticides,"
Can. J. Microbiol., 17(5):585-591 (1971).
2J Randall, G. W., M. Asce, and R. A. Lauderdale, "Biodegradation of
Malathion," J. Sanit. Eng. Div., Froc. Amer. Soc. Civil Eng.,
93(6):145-156 (1967).
141
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severe stream pollution problems resulting from malathion is minimal.
The insecticide is dissipated by aeration and is subject to micrbbial
degradation. Thus, large concentrations of malathion would not persist
in streams for extended periods of time. However, the authors point
out possible short-term toxic effects should not be ignored.
Carter and Graves (1973)!/ studied the toxicity of malathion and
several other insecticides to White River crawfish, three species of
fish, and bullfrog tadpoles. Crawfish were most sensitive to the in-
secticides tested, while the bullfrog tadpoles were least sensitive.
Malathion was only slightly toxic to all of the test species. Higher
animals were less sensitive to the insecticides than lower forms, and
responses generally varied considerably according to species.
Both reptiles and amphibians in amalathion-treated (2 Ib/acre)
watershed area were unaffected by the treatment (Peterle and Giles,
19641/). The 24-hr LC50 for Fowler's toad tadpoles and chorus frog
tadpoles exposed to malathion was 1.9 ppm and 0.56 ppm, respectively
(Sanders, 1970.I/).
J./ Carter, F. L., and J. B. Graves, "Measuring Effects of Insecticides
on Aquatic Animals," LA _Agr.. 16(2):14-15 (1973).
2f Peterle, T. J., and R. H. Giles, New Tracer Techniques for Evalu-
ating the Effects of an Insecticide on the Ecology of a Forest
Fauna, Ohio State Univ. Res. Found. Rep., 435 pages (1964).
3/ Sanders, H. 0., "Pesticide Toxicities to Tadpoles of the Western
Chorus Frog Pseudacris triseriata and Fowler's Toad Bufo wood-
housii fowleri," Copeia, 2:246-251 (1970).
142
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Coppage (1974)i/ determined the toxicity of malathion to pink
shrimp (Penaeus duorarum) in flowing seawater at 28 to 29° C and 18 to
20% salinity. After 24 hr exposure to malathion at the concentration
of 14 ppb, 32% of the test animals were dead or affected, and up to
60% inhibition of acetylcholinesterase in the ventral nerve cord was
measured.
Hansen et al. (1973)J/ studied the ability of grass shrimp
(Palaemonetes pugio) to avoid malathion and several othar pesticides
at concentrations higher and lower than the 24-hr LC^Q'S. Under these
conditions, shrimp showed no ability to avoid malathion. The authors
state that shrimp are less able to avoid, and are more sensitive to,
pesticides than fishes.
Eisler and Weinstein (1967) A/ studied changes in metal composition
of the Quahaug clam (Mercenaria mercenaria) following exposure to mala-
thion. Adult claias were exposed to graded concentrations of malathion
for 96 hr at 20°C and 24% salinity. They were apparently unaffected at
the highest level tested, 37,000 ppb of malathion. However, analysis
of whole animal and selected tissues of the exposed clams showed con-
sistent changes in levels of Na, K, Mg, Fe, and especially Ca and Zn
in comparison to untreated controls. These metal shifts present a means
of identifying unfavorable environmental conditions before more obvious
morphological or physiological changes occur.
Coppage, D. L., "Effects of Malathion on Estuarine Organisms,"
unpublished data (1974).
2J Hansen, D. J., J. M. Keltner, Jr., and S. Schimmel, "Avoidance of
Pesticides by Grass Shrimp (Palaemonetes pugio)," Bull. Environ.
Contain. Toxicol., 9(3):129-133 (1973).
3/ Eisler, R., Jr., and M. P. Weinstein, "Changes in Metal Composition
of the Quahaug Clam, Mercenaria mercenaria, After Exposure to In-
secticides," Cjiesj£eake_Jcience, 8(4):253-258 (1967).
143
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Davis and Hidu (1969)1' studied the effects of malathion and many
other pesticides on the embryonic development of the hard clam (Merce-
naria mercenaria) and the American oyster (Grassestrea virginica) and on
their larvae. Most of the chemicals affected embryonic development more
than survival or growth of larvae. Malathion was characterized as one
of three insecticides which appear to be least lethal for survival of
oysters and clams.
Sanders (1970) studied the toxicity of malathion to 4- and 5-week-
old tadpoles of Fowler's toad (Bufo woodhousii fowleri) in static bio-
assays at 15.5°C. Under these conditions, the estimated TI^Q values
for malathion were 1.9 mg/liter at 24 hr, 0.5 mg/liter at 48 hr, and
0.42 mg/liter at 96 hr. Some of the other pesticides included in these
tests were up to 10 times more toxic than malathion, while the least
toxic ones were more than 10 times less toxic.
Ranke-Rybicka (1972)—' studied the viability of tadpoles of Rana
temporaria exposed intermittently to malathion at 1.25 mg/liter. Ten
percent mortality was recorded in 30-day-old tadpoles. Ranke-Rybicka
and Stanislawska (1972)—' observed changes in periphyton organisms
caused by malathion at a concentration of 7.42 mg/liter. Protozoa and
rotifers were the most sensitive, algae the most resistant organisms.
Malacea and lonescu (1969)A/ report that in Rumania, the maximum
concentration of malathion allowable in surface waters is 0.0006 mg/liter
AI.
Field studies - Kennedy and Walsh (1970) studied the effects of
malathion on aquatic invertebrates. Ponds were treated with malathion
at 0.02 and 0.002 ppm four times over an 11-week period. In the ponds
treated at the lower rate, the total number of aquatic insects was not
I/ Davis, H. C., and H. Hidu, "Effects of Pesticides on Embryonic Devel-
opment of Clams and Oysters, and on Survival and Growth of the
Larvae," U.S. Fish Wildl. Serv., Fish Bull., 67(2):393-404 (1969).
2_/ Ranke-Rybicka, B., "Viability of Tadpoles of Rana temporaria Inter-
mittently Exposed to Organophosphorus Pesticides (Phoschlor and
Malathion)," Roez. Panstw. Zakl. Hig.. 23(3):37 (1972).
3_/ Ranke-Rybicka, B., and J. Stanislawska, "Changes in Periphyton
Organisms Caused by Organophosphorus Pesticides (Malathion, Phos-
chlor)," Roez. Panstw. Zakl. Hig.. 23(2):137-146 -(1972).
4/ Malacea, I., and M. lonescu, "Toxicity of Some Organophosphorus
Insecticides to Aquatic Organisms," Hydrobiologia, 10:31-41 (1969),
144
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significantly lower than in the untreated ponds. In the ponds treated
at the higher rates, the number of organisms was significantly lower
than that in untreated ponds. At both treatment rates, benthic organ-
isms (Chironomidae and mayflies) were significantly reduced in numbers.
Wall and Marganian (1971)!/ studied the effects of malathion
(and several other insecticides) applied against mosquitoes on the
nontarget fauna. Malathion was applied as a granular formulation
(concentration and rate not given) to 0.04 and 0.12 acre intertidal
sand plots. Malathion was less effective as a mosquito larvicide
than some of the other insecticides tested. None of the tested pesti-
cides (including malathion) appeared to directly affect bivalves or
^plankton.
Butcher et al. (1964)—' reported on a stream sampling study con-
ducted to obtain evidence of possible pesticide effects on aquatic
arthropods. Malathion from an 8.0-lb Al/gal formulation was applied by
air at the rate of 1 Ib AI in 1 gal. of water per acre to an 80-acre
block of land containing representative cover types and a small stream
traversing a considerable portion of it. The level of sampling inten-
sity in this study was not sufficient to clearly differentiate between
possible effects of the insecticide treatment and normal seasonal popu-
lation fluctuations, and/or reinfestation by multiple generation forms
(e.g., chironomids). With these reservations, the arthropod fauna of
the study area did not appear to be altered qualitatively or quantita-
tively as a result of the treatment. Catastrophic effects on nontarget
organisms would have been demonstrated by the observation methods em-
ployed, and no such effects were evident in the two most numerous taxa,
amphipods and chironomids.
As reported by Giles (1970), an application of malathion at the rate
of 0.7 Ib Al/acre to a forested watershed in Ohio resulted in a marked
I/ Wall, J., and V. M. Marganian, Jr., "Control of Culicoides melleus
(Coq) (DipterarCeratopogonidae) with Granular Organophosphorus
Pesticides, and the Direct Effect on Other Fauna," Mosquito News,
31(2):209-214 (1971).
2j Butcher, J. W., J. Truchan, R. Wilson, and J. Fahey, "Streams Sam-
pling for Evidence of Pesticide Effects on Aquatic Arthropods,"
Proc. N.C. Branch, Entomol. Soc. Amer.. 19:130-132 (1964).
145
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reduction of the numbers of aquatic insects in the stream environment,
but recovery occurred rapidly. Reptiles and amphibians were unaffected.
When malathion was used in three grasshopper control projects in
Montana (Morton, 1966), Wyoming (Henderson, 1967a), and Utah (Henderson,
1967b), somewhat varying effects on lower aquatic organisms were ob-
served. In the Montana project, there was no significant effect on the
aquatic bottom fauna from the treatment. However, there was a very sig-
nificant increase in the number of'tiriftf1 organisms that appeared 5 hr
after spraying. In the Wyoming project, there were minimal effects on
aquatic life, and drift organisms showed only a small to moderate in-
crease at any time during the spray period. Bottom animal samples indi-
cated some reduction in fish food organisms, mainly stonefly nymphs. In
the Utah project, there was no significant increase in drift organisms
after the malathion application. However, there was almost complete
mortality of mayfly, stonefly and caddisfly larvae. These differences
in the effects of the malathion treatments on the number of drift organ-
isms and on the bottom fauna are largely explained by the different
nature and flow rates of the streams in the respective study areas.
Tagatz et al. (1974) studied the effects of ground applications of
malathion on salt-marsh environments in northwestern Florida. Mala-
thion was applied repeatedly as a thermal fog at 6 oz/acre, and as a
ULV aerosol spray at 0.64 fl oz/acre in a manner typical of mosquito
control operations. Malathion did not result in deaths among confined
blue crabs (Callinectes sapidus), grass shrimp (Palaemonetes vulgaris
and P_. pugio), or pink shrimp (Penaeus duorarum). Neither the confined
animals nor the snail (Littorina irrorata) contained detectable amounts
of malathion on analysis.
The extensive data reviewed in this subsection indicate that mala-
thion is very toxic to aquatic insects, toxic to the lower aquatic
fauna, and relatively nontoxic to the lower aquatic flora. A number of
aquatic microorganisms degrade malathion. In cases where disruptions
of the aquatic fauna occur following application of malathion at insec-
ticidally effective rates, the preapplication balance appears to return
rapidly, probably due to the rapid degradation of the insecticide under
field conditions.
146
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Effects on Wildlife
Laboratory Studies - The acute toxicity of malathion to avian species
has not been as extensively studied as some other pesticides. The acute
oral LDso of malathion to female mallard ducks is 1,485 mg/kg (Tucker
and Crabtree, 1970^') . The subacute oral toxicity of malathion has
been studied in more species than the acute oral, and the subacute oral
toxicity is summarized in Table 25. The subacute studies revealed that
the potential hazard to avian species tested is very low. Malathion
ULV at one and 10 times the normal application rate did not produce any
detectable neurotoxic symptoms to bobwhite quail treated 20 times within
a 34-day period. Food consumption was normal and cholinesterase activ-
ity was not depressed (Joseph et al., 1972).
The acute toxicity symptoms of malathion poisoning in avian species
consist of ataxia, walking high on toes, wing drop, falling stiffly with
wings spread, tenesmus, foamy salivation and tremors (Tucker and
Crabtree, 1970).
Field Studies - Malathion was applied to about 4,300 acres of meadow
and rolling grasslands in the Dixie National Forest, Utah, at the rate
of about 8 fl oz/acre (Henderson, 1967b), as already mentioned in the
preceding subsection. Many species of birds and some mammals, includ-
ing deer, were relatively abundan.t in the treated area. No specific
studies were conducted, but project members reported no adverse effects
or behavioral changes in any of the wildlife species. McEwen et al.
(1972)^-'- studied the effects on wildlife of malathion (and other insec-
ticides) at rates required for grasshopper control in test plots on
short-grass range in Montana, New Mexico, and Wyoming. Effects on wild-
life were determined by way of bird and small mammals censuses, carcass
counts, and residue analyses. Malathion applied at 6.8 oz Al/acre did
not result in any observable direct effects on wildlife.
I/ Tucker, R. K., and D. G. Crabtree, Handbook of Toxicity of Pesticides
to Wildlife, Bureau of Sport Fisheries and Wildlife, Denver Wild-
life Research Center, Resource Publication No. 84, pp. 76-77 (1970)
2/ McEwen, L. C., C. E. Knittle, and M. ,L. Richmond, "Wildlife Effects
from Grasshopper Insecticides Sprayed on Short-Grass Range," J_._
Range Mgmt.. 25(3):188-194 (1972).
147
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Table 24. SUBACUTE TOXICITY OF MALATHION TO AVIAN SPECIES
Species
Bobwhite quail
(Colinus virginianus)
Japanese quail
(Coturnix japonica)
Pheasant
(Phasianus colchicus) '
Mallard duck
(Anas p 1 a ty rhyncho s )
5 -Day median lethal
concentration (LCe^)*
(ppm)
3,497
2,128
4,320
> 5,000
References
a/
a/
a/
a/
* LC50: ppm compound (AI) in ad libitum diet expected to produce 507o
mortality in 8 days (5 days on toxic diet followed by 3 of untreated
diet).
a/ Heath, R. G., J. W. Spann, E.' F. Hill, and J. F. Kreitzer, "Compara-
tive Dietary Toxicities of Pesticides to Birds," U.S. Bureau of
Sport Fisheries and Wildlife, Special Scientific Report—Wildlife
No. 152, pp. 1-40 (1972).
148
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Parsons and Davis (1971)— investigated the short-term effects of
aerial spraying of malathion on quail, migratory birds, and nongame
birds using cover or prairie lakes adjacent to cotton fields treated
with insecticides for the control of the boll weevil. No bird mortal-
ity or other evidence of direct adverse effects were observed on any of
the land or water areas sprayed with malathion at the rate of 12 to 16
fl oz/acre. Quail which were caged and exposed to each spray in the
field and fed on sprayed feed showed small but nonsignificant differ-
ences in growth rates compared to untreated birds.
Joseph et al. (1972) reported that mice and quail did not exhibit
any poisoning symptoms when they were exposed to ground applications of
ULV malathion at the recommended rate (1.5 fl oz/min), and a second rate
10 times that concentration. Twenty applications were made over a 34-
day period. Tests for red cell cholinesterase inhibition 24 hr after
the last exposure were negative in both species.
In the study by Giles (1970) already mentioned above, wildlife
species were observed following application of malathion at the rate of
0.7 Ib/acre to a forested watershed in Ohio. Birds in the treated area
appeared to be noticeably quiet for 2 days after spraying, but no last-
ing effects were noted. Populations of mice and chipmunks appeared to
be reduced by at least 30%. Shrews and larger mammals were unaffected.
Culley and Applegate (1967 )£' determined insecticide residues in
representative species of reptiles, birds, and wild mammals from the
Presidio Valley in Texas. This valley has approximately 384,000 acres
of land, of which 2,900 acres are under cultivation and pesticide treat-
ments. The valley is surrounded by mountains and represents a point
source of insecticide application within a large isolated area. Speci-
mens for analysis were obtained by shooting or trapping from insecticide-
exposed and nonexposed areas. Under a Federal program, a total of 17,640
Ib of malathion were applied in seven low-volume, high-concentration sprays.
No malathion residues were detected in any of the samples analyzed, including
lizard tail muscle, brain tissue, liver, coelom fat, and stomach contents;
I/ Parsons, J. K., and B. D. Davis, "The Effects on Quail, Migratory
Birds, and Nongame Birds from Application of Malathion and Other
Insecticides," Tech. Series No. 8, Texas Parks and Wildl. Dept.,
pp. 1-20 (1971).
2/ Culley, D. C.', and H. G. Applegate, "Insecticide Concentrations in
Wildlife at Presidio, Texas," Pest Monit. J.. l(2):21-28 (1967).
149
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sparrow breast muscle, brains, liver and gizzards; and in leg muscles and
livers of pocket mice and kangaroo rats. Some of these samples were obtained
within 6 weeks after the malathion applications. The authors concluded
that malathion residues rapidly disappeared from the ecosystem studied.
Bejer-Petersen et al. (1972)i' studied the effects of spray treat-
ments of malathion and other insecticides in forests on birds living in
nest boxes. Malathion spraying (rate not given in abstract) was carried
out in 1965 and in 1967 at a time when nestlings of Parus major and P_.
ater were most numerous. The malathion treatments did not significantly
affect the birds' breeding success, nor result in loss of nestlings.
However, reduced brain cholinesterase activity was observed in one or
two of the broods, of each species.
The studies reviewed in this subsection indicate that many species
of wildlife exposed to malathion applications at dosage rates required
for insect control tolerate the insecticide rather well. Effects on
wildlife outside of target areas appear to be minimal. Furthermore, as
reported in the subsection on "Production and Use," malathion is regis-
tered, recommended and used for the control of various insects, mites,
and ticks directly on animals, including cattle, horses, hogs, sheep,
goats, dogs, cats, chickens, ducks, geese, and turkeys. These facts
indicate that malathion has a favorable safety margin between target
pests on the one hand, and host and nontarget higher terrestrial animals
on the other.
Effects on Beneficial Insects
2/
Bees - Anderson and Tuft (1952)— determined the toxicity of many dif-
ferent pesticides to honeybees in laboratory experiments. Malathion
was among those that were most toxic to the bees; 100% were killed in a few
minutes. In field tests by Anderson and Atkins (1958)£J malathion was
rated as "moderately toxic" to honeybees.
-I/ Bejer-Petersen, B., R. R. Hermansen, and M. Weihe, "On the Effects
of Insecticide Sprayings in Forests on Birds Living in Nest Boxes,"
Dan. Ornithol. Foren. Tidsskr., 66(1,2):30-50 (1972).
2/ Anderson, L. D., and T. 0. Tuft, "Toxicity of Several New Insecti-
cides to Honey Bees," J. Econ. Entomol., 45:466-469 (1952).
3_/ Anderson, L. D., and E. L. Atkins, Jr., "Toxicity of Pesticides to
Honey Bees in Laboratory and Field Tests in Southern California,
1955-1956," J. Econ. Entomol.. 51:103-108 (1958).
150
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Johansen et al. (1965)— investigated the effects on bees of a ULV
application of malathion on blooming alfalfa at the rate of 10 oz/acre.
Malathion killed field bees for at least 4 days. Bees caged on treated
foliage also exhibited above normal mortality for 4 days. There was no
perceptible fumigant action. Bees from colonies 2.5 miles away that
foraged in the treated area were killed. Living hive bees became con-
taminated with malathion residues. On the fifth day after treatment,
malathion residues on alfalfa foliage declined markedly, apparently due
to rainfalls which began on the fourth day. Covering bees for 2 days
with wet burlap tarpaulins did not afford sufficient protection. The
authors emphasize that the malathion ULV application gave more than
four times the residual action usually encountered following dilute
malathion applications.
Levin et al. (1968)—' also reported unexpected injury to bees from
malathion ULV applications in Wyoming for the control of grasshoppers.
Large numbers of honeybees were killed, and about 600 colonies were
seriously damaged following a malathion ULV application at the rate of
8 fl oz/acre. Malathion residues were detected in alfalfa (12 to 29
ppm), in pollen (0.43 to 11.1 ppm), and in dead bees (less than 0.01 to
0.37 ppm) for as long as 8 days after the application. The authors con-
clude that undiluted malathion at this rate must be considered danger-
ously toxic to honeybees.
Johansen (1972)—' studied the toxicity of field-weathered residues
of malathion and other insecticides to different species of bees. Mala-
thion from a 5-lb/gal emulsifiable liquid was applied to alfalfa at the
rate of 1.0 Ib Al/acre. Three kinds of bees were exposed to the mala-
thion residues 10 hr after application. Bee mortality was determined
after 24 hr and was 100% in alfalfa leafcutte-r bees (Megachile rotun-
data) and honeybees (Apis mellifera); and 47% in alkali bees (Nomia
melanderi).
I/ Johansen, C. A., M. D. Levin, J. D. Eves, W. R. Forsyth, H. B.
Busdicker, D. S. Jackson, and L. I. Butler, "Bee Poisoning Hazard
of Undiluted Malathion Applied to Alfalfa in Bloom," Washington
Agr. Exp. Sta. Circular No. 455 (1965).
2_/ Levin/M. D., W. B. Forsyth, G. L. Fairbrother, and F. B. Skinner,
"Impact on Colonies of Honey Bees for Ultra-Low-Volume (Undiluted)
Malathion Applied for Control of Grasshoppers," J. Econ. Entomol.,
61(l):58-62 (1968).
3/ Johansen, C.*A., "Toxicity of Field-Weathered Insecticide Residues
to Four Kinds of Bees," Environ. Entomol., 1(3):393-394 (1972).
151
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Johansen and Davis (1972)— compared the toxicity of malathion and
other insecticides .against the western yellow jacket (Vespula
pennsylvanica) and the honeybee (A. me11ifera). Malathion (and most of
the other insecticides studied) was somewhat more toxic to the western
yellow jacket (11)50 3.3 ug/g) than to the honeybee (LD5Q 5-5 ug/g) •
o /
Mayland and Burkhardt (1970)— exposed honeybees to surfaces of
plastic, glass, alfalfa leaves, rhubarb leaves, filter paper, and soil
treated with malathion (and, in separate tests, with other insecticides).
There were sufficient differences in bee mortalities resulting from ex-
posure to the different insecticide-treated surfaces to indicate that
the surface must be taken into consideration in studies on the effects
of insecticides on bees in the laboratory. In all test series, mala-
thion was highly toxic to bees. Three-week-old bees were least suscep-
tible to the insecticides in comparison to other age groups.
Entomologists from abroad report generally similar observations on
the toxicity of malathion to honeybees. Beran and Neururer (1955)— de-
termined the toxicity of malathion and other insecticides to bees by
oral and tarsal application, and by exposing bees to insecticide-impreg-
nated filter paper. By all three methods of application, malathion was
highly toxic to the bees. Greenhouse and field tests conducted over a
5-year period also indicated that malathion is toxic to bees (Beran and
il ^ /
Neururer, 1956-L'). By contrast, Gorecki (1973)—' rates malathion among
the number of "organophosphorus insecticides safe to bees."
I/ Johansen, C. A., and H. G. Davis, "Toxicity of Nine Insecticides to
the Western Yellowjacket," J. Econ. Entomol., 65(l):40-42 (1972).
2/ Mayland, P. G., and C. C. Burkhardt, "Honey Bee Mortality as Related
to Insecticide-Treated Surface and Bee Age," J. Econ. Entomol.,
63(5):1437-1439 (October 1970).
3_/ Beran, F., a,nd J. Neururer, "The Action of Plant Protectants on the
Honey Bee (Apis mellifera). I. Toxicity of Plant Protectants to
Bees," Pflanzenschutz Ber., 15:97-147 (1955).
4/ Beran, F., and J. Neuruer, "Actions of Plant Protectants on the
Honey Bee (Apis mellifera). II. Toxicity of Plant-Protection
Agency to Bees," Pflanzenschutz Ber., 17:113-190 (1956).
5_/ Gorecki, K., "Harmful Effects of Insecticides Used in Poland on Apis
mellifica (Honey Bees)," Pol. Pismo Entomol.. 43(1): 201-210 ,(1973).
152
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Markosyan (1968)i/ and Wiese (1957, 1958a, 1958b)2*3'4/ found
malathion to be very toxic to bees, based on a variety of laboratory
and field tests.
Malathion labels carry the notice, "This product is highly toxic
to bees exposed to direct treatment." In the light of the laboratory
and field data reported above, this warning appears to be highly war-
ranted, especially in the case of ULV applications.
Parasites and Predators - The importance of naturally occurring para-
sites and predators of insect and mite pests in suppressing these pests
and reducing or preventing economic damage has been increasingly recog-
nized in recent years. A number of investigators have studied the
effects of malathion on such parasites and predators.
Harries and Valcarce (1955)— studied the toxicity of malathion 5%
dust applied to sugar beet plants on which three species of beneficial
insects were confined for 24 hr in cellulose acetate cages. The mala-
thion treatment resulted in the following mortalities: 90% in adult
convergent lady bettles (Hippodamia convergens), 477» in striped collops
(Collops vittatus), and 10070 in spotted lady beetles (Colcomagilla
maculata). Malathion was among the insecticides most toxic to these
beneficial insects under the experimental conditions studied.
Burke (1959)- investigated the toxicity of several insecticides
including malathion to beneficial cotton insects. Adult Orius insidiosus
I/ Markosyan, Z. K., "Effects of Pesticides on Bees Under Hothouse Con-
ditions," Mater. Sess. Zakavkaz. Sov. Koord. Nauch.-Issled. Rab.
Zushch. Rast., pp. 688-690 (1968).
2/ Wiese, I. H., "Toxicity of Modern Insecticides to the South African
Honey Bee," S. African Bee J., 32:2,7,9-10 and 3,6-7,9-10 (1957).
3_/ Wiese, I. H. , "The Toxicity of Modern Insecticides to the South
African Honey Bee," African Beekeeping, 1:14-15 (1958a).
4/ Wiese, I. H., "The Toxicity of Modern Insecticides to the South
African Honey Bee," S. African Bee J.., 32:4,5,7; 5,9-11 and 6,10-11
(1958b).
5_/ Harries, F. H., and A. C. Valcarce, "Laboratory Tests of the Effect
of Insecticides on Some Beneficial Insects," J. Econ. Entomol.,
48:614 (1955).
6/ Burke, H. R,,, "Toxicity of Several-Insecticides to Two Species of
Beneficial Insects on Cotton," J. Econ. Entomol., 52:616-618 (1959),
153
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were confined to insecticide-treated cotton plants for 2 days. Under
these conditions, malathion was one of the insecticides most toxic to
this species.
Lingren et al. (1972)—' studied the toxicity of malathion and
other insecticides to two species of parasitic wasps, Apanteles
marginiventris and Campoletis perdistinctus. The LD50 of malathion
applied topically to adult male C. perdistinctus was 0.0064 ug/insect.
When malathion was applied topically to cocoons of C_. perdistinctus,
107» cocoon mortality occurred at the rate of-0.64 ug/cocoon, while 0.064
ug/cocoon produced 6% cocoon mortality. In these tests, malathion was
among the more toxic insecticides.
Ridgway et al. (1974)2/ studied the effects of malathion applied
at 0.25 Ib/acre from a 967» Al ULV formulation to beneficial insects on
cotton. In laboratory and field tests malathion was highly toxic to
green lacewing larvae (Chrysopa spp.), the adult big-eyed bug (Geocoris
punctipes), and the adult lady beetle (Hippodamia convergens).
Hamilton and Kieckhefer (1969)—' investigated the toxicity of mala-
thion to predators of the English grain aphid (Macrosiphum avenge).
Adult and larval forms of the three most numerous and ubiquitous pred-
ators of cereal aphids in South Dakota, Hippodamia convergens (the con-
vergent lady beetle), Nabis americoferus, and Chrysopa carnea were
field-collected for laboratory mortality tests. By topical application
to adults, the LDeQ °f malathion to the aphid 4 hr post treatment was
3.6 ug/g, while it ranged from 68 to 830 ug/g to adults, nymphs and
larvae of the three predators. LC50 values of malathion to the same
insects were determined by exposing the insects to 4-hr-old deposits of
appropriate concentrations. Again, the LCgQ values of malathion to the
predators were much higher than to the aphid.
I/ Lingren, P. D., D. A. Wolfenbarger, J. B. Nosky, and M. Diaz, Jr.,
"Response of Campoletis perdistinctus and Apanteles marginiventris
to Insecticides," J. Econ. Entomol., 65(5):1295-1299 (1972).
2_/ Ridgway, R. L., C. B. Cowan, and J. R. Cage, unpublished data (per-
sonal communication) (1974).
3_/ Hamilton, E. W., and R. W. Kieckhefer, "Toxicity of Malathion and
Parathion to Predators of the English Grain Aphid," J. Econ.
Entomol.. 62(5):1190-1192 (October 1969).
154
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Teetes (1972)!/ reported that when insecticides were applied to
grain sorghum for the control of the green bug (Schizaphis graminum),
populations of beneficial insects including lady beetles (Hippodamia
convergens) and green lacewings (Chrysopa spp.)> declined. One of the
highest percentages of mortality among the beneficial species was seen
following applications of malathion. Malathion at 0.5 and 0.1 Ib Al/acre
showed one of the greatest residual effects on the beneficial insects
among all insecticides studies.
Johansen et al. (1965) observed that an application of malathion
ULV to blooming alfalfa at the rate of 10 oz/acre resulted in reduction
of lady beetle populations, while nabid and anthocorid bugs appeared to
be unaffected. v
In studies on the effects of insecticides on the fauna of apple
orchards in Nova Scotia (MacPhee and Sanford, 1956=- ), malathion had
drastic adverse effects on predators and parasites.
Hill et al. (1971)-/ reported on the effects of aerial ULV appli-
cations of malathion for mosquito control at the rate of 0.2 Ib Al/acre
in Texas. Nine malathion ULV applications were made on three towns.
Nontarget insect counts were obtained by use of sweep nets and a vehicle-
mounted trap. The insect orders Homoptera and Hemiptera declined during
the treatment period, whereas other insect orders including Diptera
(with the exception of Culicidae) were not affected. The authors con-
cluded from their observations that low-volume aerial applications of
malathion for mosquito control are sufficiently safe to the nontarget
fauna to justify the product's use, although beekeepers should be noti-
fied to cover beehives during application.
A number of reports from abroad generally confirm that there is
little, if any, selectivity between the toxicity of malathion to target
insects and to beneficial parasites and predators occurring on the same
I/ Teetes, G. L., "Differential Toxicity of Standard and Reduced Rates
of Insecticides to Greenbugs and Certain Beneficial Insects," Tex.
Agr. Exp. Sta., Progress Report No. PR-3041, 9 pages (1972).
2_/ MacPhee, A. W., and K. H. Sanford, "Influence of Spray Programs on
the Fauna of Apple Orchards in Nova Scotia. X. Effects on Some
Beneficial Arthropods," Can. Entomol., 88:631-634 (1956).
3/ Hill, E. F., D. A. Eliason, and J. W. Kilpatric, "Effects of Ultra-
Low Volume Applications of Malathion in Hale County, Texas,"
J. Med. Entomol., 8(2):173-179 (1971).
155
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host plant. Manser and Bennett (1962-1963)i' found that malathion would
cause mortality of Lixophaga diatraeae, a parasite of the sugarcane
borer (Diatraea saccharalis) if present in the field during application.
Because of the short residual action of malathion, the authors believe
that reduction in the parasite populations would only be temporary.
2/
Pradhan et al. (1968)— found that malathion was more toxic to an
aphid predator, Coccinella septempunctata, than to the mustard aphid
(Lipaphis erysimi). Satpathy et al. (1968)1.' studied the toxicity of
malathion and other insecticides to the aphid predator Chilomenes
sexmaculata by feeding adult beetles with insecticide-poisoned aphids.
Malathion was among the insecticides most toxic to the predator. Teotia
and Tiwari (1972)z/ also found malathion to be among the insecticides
most toxic to the aphid predator Coccinella septempunctata. Kowalska
and Szczepanska (1971)— described malathion as among those insecticides
showing varying but persistent degrees of toxicity against such natural
enemies of aphids as lacewings, lady beetles, and Hymenoptera (Encarsia
formosa and Phytoseiulus persimilis), introduced into Poland specifically
for use as entomophagous agents. Abdelrahman (1973)—' reported that the
natural enemies of the California red scale (Aonidiella aurantii) were
considerably more susceptible to malathion than female red scales in the
second moult state. In this state, the red scale was 707 times more
I/ Manser, P. D., and F. D. Bennett, "Possible Effects of the Applica-
tion of Malathion on the Small Moth Borer, Diatraea saccharalis
(F), and Its Parasite Lizophaga diatraeae (Tns.) in Jamaica,"
Bull. Entomol. Res., 53:75-82 (1962/1963).
2j Pradhan, S., M. G. Jotwani, Sarup, Prakash, "Bioassay of Different
Insecticides on the Important Insect Pests and Predators of Agri-
cultural Importance," Pest. Symp., pp. 92-103 (1968).
3_/ Satpathy, J. M., G. K. Padhi, and D. N. Dutta, "Toxicity of Eight
Insecticides to the Coccinellid Predator Chilomenes sexmaculata,"
Indian J. Entomol., 30(1):130-132 (1968).
4/ Teotia, T. P, S., and G. C. Tiwari, "Toxicity of Some Important
Insecticides to the Coccinellid Predator, Coccinella septempunc-
tata," Labdev, Part B, 10(1):17-18 (1972).
5_/ Kowalska, T., and K. Szczepanska, "Toxicity to Entomophages of Some
Pesticides Used in Poland," Biul. Inst. Ochr. Rosl., 50:179-194
(1971).
6/ Abdelrahman, I., "Toxicity of Malathion to the Natural Enemies of
California Red Scale, Aonidiella aurantii (Hemiptera:Diaspididae),'
Aust. J. Agr. Res., 24(1):119-133 (1973).
156
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tolerant to malathion than Aphytis melinus; 294 times more tolerant
than Comperiella bifasciata, and 10 times more tolerant than Lindorus
lophanthae. (Results of tests indicate malathion is not suitable in
an integrated program for the control of this citrus pest.)
The extensive data summarized in this subsection indicate that in
most crop-pest-predator/parasite systems, malathion appears to have
little, if any, selective toxicity to pest species. In some instances,
it appears to be more toxic to beneficial than to pest insects.
Interactions with Lower Terrestrial Organisms
Reviews - The relationships between insecticides and microorganisms
have recently been reviewed by several authors. Matsumura and Boush
(1971)— report that organic phosphate insecticides (including mala-
thion) have thus far not presented serious problems in soils as regards
undesirable persistence, nor demonstrated a potential for buildup in
food chains. Although considerable variations exist between individual
organophosphates, most of them are readily degraded in the soil, mainly
by hydrolytic and oxidative means.
Matsumura and Boush also point out that, although several workers
have demonstrated in the laboratory that certain microorganisms are able
to degrade even the most stable and persistent organic insecticides, it
has not as yet been demonstrated whether or not this occurs in nature,
or even that these compounds serve as nutritional or energy sources for
organisms. "In fact there are no reports as yet that these chemicals
have been shown to serve as sole nutritional carbon sources."
Another recent review of the interactions between pesticides (in-
cluding malathion) and the soil fauna has been presented by Drift
(1970)M
3/
Laboratory and Field Studies - Matsumura and Boush (1966)— found that
malathion was metabolized quickly by a soil fungus, Trichoderma viride,
I/ Matsumura, F., and G. M. Boush, "Metabolism of Insecticides by Micro-
organisms," Soil Biochem., 2:320-336, Marcel Dekker, New York (1971),
2_/ Drift, J., "Pesticides and Soil Fauna," Meded. Rijksfac. Landbouw-
wetensch., Gent, 35(2):707-716 (1970).
3_/ Matsumura, F., and G. M. Boush, "Malathion Degradation by Trichoderma
viride and a Pseudomonas Species," Science, 153(3741):1278-1280
(1966). •
157
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and a bacterium, Pseudomonas sp., which were isolated from Ohio soils
that had been heavily treated with insecticides. The breakdown capabil-
ities of 16 variants of T. viride were studied. Certain colonies from
this species had a very marked ability to degrade malathion through the
action of one or several carboxylesterase enzymes. Both of these soil
organisms occur commonly in many soils and may assist in the elimina-
tion of some insecticide residues. Alternatively, the residual toxic-
ity of such insecticides might be extended by a reduction of the popu-
lations of these microorganisms in the soil.
Garretson and San Clemente (1968)-=-' studied the interactions be-
tween malathion (and several other insecticides) and nitrifying bac-
teria. Of all chemicals tested, malathion was the least toxic to
Nitrobacter agilis; at the highest rate tested, 1,000 ug/ml, it only
caused some delayed nitrification. However, malathion caused complete
inhibition of Nitrosomonas europaea at 10 ug/ml. The authors" empha-
sized that these laboratory findings should not be extrapolated to
field conditions.
"> I
Walker and Stojanovic (1974)— isolated 18 soil bacteria and found
that, of these, five were capable of utilizing the malathion molecule
as a substrate. Degradation of added malathion ranged from 47 to 9570.
An Arthrobacter species was the most efficient malathion utilizer; it
degraded the chemical to its half-ester, dicarboxylic acid, and several
other identified and unidentified metabolites.
Anderson (1971)^.' investigated the capacity of several fungi
isolated from an agricultural loam soil to degrade DDT. In shake
cultures, Mucor alternans partially degraded DDT in 2 to 4 days into
two water-soluble metabolites. Malathion did not affect the growth
of the fungus or its degradation of DDT.
I/ Garretson, A. L., and C. L. San Clemente, "Inhibition of Nitrifying
Chemolithotrophic Bacteria by Several Insecticides," J. Econ.
Entomol., 61(1):285-288 (1968).
2/ Walker, W. W., and B. J. Stojanovic, "Malathion Degradation by an
Arthrobacter Species," J. Environ. Qual.. 3(1):4-10 (1974).
3/ Anderson, J. P. E., "Factors Influencing Insecticide Degradation by
a Soil Fungus, Mucor alternans," Piss. Abstr. Int., 32(6):3114B-
3115B (1971).
158
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Mostafa et al. (1972a)- found that two soil microorganisms,
Rhizobium leguminosarum and R. trifolii, metabolized 32P-labeled mala-
thion at the rate of 67 and 87%, respectively, in 1 week. Several mala-
thion hydrolysis products were identified. The nature of the breakdown
products indicates the involvement of a very active carboxylesterase
system plus, probably, one or several additional enzymes. In a related
study, Mostafa et al. (1972b)i/ found that the fungi Penicillium notatum
and Aspergillus niger metabolized 76 and 59%, respectively, of 32P-
labeled malathion into water-soluble metabolites within 10 days. Smaller
fractions (7 and 25%, respectively) were metabolized into CHC^-soluble
compounds.
Sethunathan and Yoshida (1972)2/ found that malathion was not de-
graded by a cell-free extract of a species of Flavobacterium isolated
from water of a rice field previously treated with diazinon. Several
other phosphate insecticides having a P-O-C bond were rapidly degraded
by this extract.)
In a field study in which malathion was applied to a forested
watershed in Ohio at the rate of 0.7 lb Al/acre (Giles, 1970), no
effects from the insecticide treatment were observed on bacteria or
fungi. Soil microarthropods were affected for a short time, but earth-
worms and snails showed no adverse symptoms.
Getzin and Rosefield (1968, 1971)-^-'• and Satyanarayana and Getzin
(1973)—' extracted a heat-labile, water-soluble substance that accelerated
\J Mostafa, I. Y., I. M. I. Fakhr, M. R. E. Bahig, and Y. A. El-Zawahry,
"Metabolism of Organophosphorus Insecticides. XIII. Degradation of
Malathion by Rhizobium spp.," Arch. Mikrobiol., 86(3):221-224 (1972a).
2/ Mostafa, I. Y., M. R. E. Bahig, I. M. I. Fakhr, and Y. Adam, "Metab-
olism of Organophosphorus Insecticides. XIV. Malathion Breakdown
by Soil Fungi," Z. Naturforsch., B 27(9):115-116 (1972b).
3_/ Sethunathan, N., and T. Yoshida, "Conversion of Parathion to Para-
nitrophenol by Diazinon-Degrading Bacterium," Proc. Inst. Environ.
Sci. Ann. Tech. Meet., 18:255-257 (1972).
4/ Getzin, L. W., and I. Rosefield, "Organophosphorus Insecticide Degra-
dation by Heat-Labile Substances in Soil," J. Agr. Food Chem.,
16f4):598-601 (1968).
5_/ Getzin, L. W., and I. Rosefield, "Partial Purification and Proper-
ties of a Soil Enzyme That Degrades the Insecticide Malathion,"
Biochem,, Biophys. Acta, 235(3):442-453 (1971).
6/ Satyanarayana, T., and L. W. Getzin, "Properties of a Stable Cell-
Free Esterase from Soil," Biochem., 12(8):1566-1572 (1973).
159
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the degradation of malathion from nonautoclaved and radiation-sterilized
soil. The substance was destroyed by heating soil suspensions for 10
min at 90°C, but most of its activity was retained in soils held at 25°C
for 2 or 3 months after radiation sterilization. In subsequent tests,
the substance was purified and characterized. Unlike the animal en-
zymes which hydrolyze malathion, the preparation catalyzed the hydro-
lysis of aromatic, but not aliphatic esters. The substance exhibited
all properties essential to stability in the soil, including thermal
stability, resistance to proteolytic attack, tolerance to pH extremes,
apparent lack of requirement for cofactors, and tolerance to heavy met-
als and common enzyme inhibitors. The authors suggest a carbohydrate-
protein structure and propose that this cell-free soil enzyme should be
an excellent tool for investigating enzymatic biological transformations
in soil.
Kutches (1970)-/ and Kutches et al. (1970)- studied the effects of
malathion and 11 other pesticides on the microbial activity of sheep
rumen liquor in vitro. Dry matter disappearance, volatile fatty acid
production, and alterations in rumen ciliated protozoal numbers were the
criteria measured. Relatively high concentrations (500 ug/ml) of mala-
thion (and of the other pesticides) were tolerated by rumen microorgan-
isms without deleterious effects on rumen function. The authors con-
clude that the concentrations of pesticides that might be ingested by
ruminants by way of contaminated feedstuffs would have no or negligible
effects on rumen digestibility or other rumen functions. Pesticide
residues that might be found on contaminated feedstuffs would be ex-
pected to be much lower than those studied.
3/
Nestor (1972)- found that malathion inhibited the growth of gram-
positive bacteria at concentrations ranging from 5 to 100 ug/liter.
The growth of gram-negative bacteria was inhibited to a lesser degree.
Xylene and emulsifiers used in insecticidal formulations exhibited a
less marked bactericidal effect. Malathion had a certain bacterio-
static effect against Baccillus anthracis and enterococci.
I/ Kutches, A. J., "Influence of Pesticides on Rumen Microbial Metab-
olism," Piss. Abstr. Int., 31(5):2387B-2388B (1970).
2/ Kutches, A. J., D. C. Church, and F. L. Duryee, "lexicological Ef-
fects of Pesticides on Rumen Function in vitro," J. Agr. Food
Chem., 18(3):430-433 (1970).
3_/ Nestor, I., "Influence of Organophosphorus Insecticides of the Mala-
thion and Bromofos Type on Gram-Positive Bacteria," Igiena, 20(12):
723-730 (1972).
160
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The studies summarized in this subsection indicate that a number of
soil microorganisms are capable of degrading malathion. However, no
reports were found indicating if and to what extent such processes may
occur under field conditions in situ.
Residues in Soil
Laboratory Studies - MacNamara (1969)^' and MacNamara and Toth (1970)-'
investigated the adsorption and release of malathion, using various sat-
urated clay systems, humic acid, and 10 New Jersey soils (A and B hori-
zons known to be free of organic pesticide contamination). The adsorp-
tion of malathion by clay minerals appeared to be related to the cation
exchange capacities of the clays. More malathion was adsorbed by
potassium-saturated systems than by the calcium-, magnesium- or hydrogen/
aluminum-saturated clays. More malathion was adsorbed by the humic acid
system than by any of the clay systems. Adsorption was higher in the
soils with higher organic matter content. Desorption studies showed that
electrolyte solutions either suppressed or had little effect on the re-
lease of malathion.
Bowman (1970)- and Bowman et al. (1970)-/ studied the effect of
water on the adsorption of malathion on five montmorillonite systems.
Malathion penetration of the interlayer regions of montmorillonite was
very slow, below 30% relative humidity. At relative humidities exceed-
ing 40%, malathion penetrated within minutes and was adsorbed as a dou-
ble layer. The mechanism of adsorption was through a hydrogen bonding
interaction between the carbonyl oxygen atoms and the hydration water
shells of the saturating cations. Changes in the hydration status of
the clay system produced marked reversible alterations in the spectrum
of adsorbed malathion that were believed due to orientation and inter-
action effects. No degradation of adsorbed malathion was observed.
I/ MacNamara, G. C., "Adsorption of Some Pesticides on Soils, Clay
Minerals and Humic Acid," Piss. Abstr., 29:2260B (1969).
21 MacNamara, G. C., and S. J. Toth, "Adsorption of Linuron and Mala-
thion by Soils and Clay Minerals," Soil Sci., 109(4):234-240 (1970).
3/ Bowman, B. T., "The Effect of Water Upon Malathion Adsorption Onto
Five Montmorillonite Systems," Piss. Abstr. Int., 31(3):1005B-
1006B (1970).
4/ Bowman, B. T., R. S. Adams, Jr., and S. W. Fenton, "Effect of Water
Upon Malathion Adsorption Onto Five Montmorillonite Systems," J_._
Agr. Food Chem., 18(4)-.723-727 (1970).
161
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Meyers et al. (1970)— studied the adsorption of malathion on pond
sediments and watershed soils. The clay fractions of both the sediment
and the soil contained kaolinite, micaceous minerals, and vermiculite.
Among several insecticides studied, malathion was adsorbed to the
greatest extent.
9/
Konrad et al. (1969)— found that the rate of malathion degrada-
tion in soils was directly related to the extent of malathion adsorp-
tion, suggesting that degradation occurred by a chemical mechanism
which was catalyzed by adsorption. In laboratory studies with three
different soil types, 50 to 90% of the initial quantity of malathion
was degraded in 24 hr, depending on the type of soil, in both sterile
and nonsterile systems. No lag phase occurred prior to degradation.
In aqueous soil-free systems inoculated with a soil extract, a lag phase
of about 7 days occurred, followed by rapid malathion loss. It is con-
cluded that in soils, complete chemical degradation of malathion oc-
curred prior to microbial adaptation to the chemical. The chemical
reaction is complete before the end of the biological lag phase is
achieved.
3 /
Walker and Stojanovic (1973)— investigated the chemical and micro-
biological degradation of malathion in three Mississippi soils (Trinity
loam, Freestone sandy loam, and Okolona clay), and in aqueous dilutions
prepared from them. In all cases, malathion degradation was more rapid
under nonsterile than under sterile conditions, indicating the involve-
ment of soil microorganisms. The amount of microbial as compared to
chemical degradation appeared to increase with increased soil organic
matter and was directly dependent on soil pH. In all three soils and
in the aqueous systems, microbiological degradation predominated. Mala-
thion was quite stable under neutral or acid pH conditions, but was
susceptible to hydrolysis in the alkaline range.
I/ Meyers, N. L., J. L. Arlrichs, and J. L. White, "Adsorption of In-
secticides on Pond Sediments and Watershed Soils," Proc. Indiana
Acad. Sci., 79:432-437 (1970).
2/ Konrad, J. G., G. Chesters, and D. E. Armstrong, "Soil Degradation
of Malathion, a Phosphorodithioate Insecticide," Soil Sci. Soc.
Amer. Proc., 33(2):259-262 (1969).
3/ Walker, W. W., and B. J. Stojanovic, "Microbial Versus Chemical
Degradation of Malathion in Soil." J. Environ. Qual., 2(2):229-
232 (1973).
162
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Getzin and Rosefield (1971) studied the persistence of malathion in
nonsterile, heat-sterilized, and radiation-sterilized soils. Malathion
(and several other pesticides studied) degraded fastest in nonsterile
soils. Malathion decomposed much faster in irradiated than in auto-
claved soil.
Chopra and Girdhar (1971)- studied the persistence of malathion in
Punjab soils. Malathion was degraded at different rates in the three
soils. Degradation increased with increased exposure time to UV light,
relative humidity, temperature, and concentration of the insecticide.
Malathion decomposed more rapidly in alkaline than in acidic soils.
\ Nayshteyn et al. (1973)-' studied the stability decomposition of
malathion and several other pesticides in artificially acidified and
alkalinized soils with pH ranges of 3 to 4.6 and 8.7 to 9.6. Malathion
was applied at 2 and 200 mg/kg at a soil temperature of 18 to 20°C.
Malathion was more stable in the acidic soils. The rate of degradation
in native and sterile soils was comparable. The authors concluded that
the role of soil microorganisms in the degradation of malathion is of
secondary importance compared to that of chemical reactions.
3/
Galley (1972)— used thin-layer chromatography to measure semi-
quant i tat ively the persistence of malathion and several other organo-
phosphates in hen house litter. Malathion disappeared within 4 hr of
application, while several of the other insecticides studied were con-
siderably more persistent.
Kearney and Helling (1969)— presented an excellent discussion of
the pertinent reactions associated with pesticide decomposition in
soils. The principal reactions associated with pesticide decomposition
in the soil are discussed in considerable detail. However, this review
contains few specific data on malathion.
I/ Chopra, S. L., and K. C. Girdhar, "Persistence of Malathion S-1,2-
bis (Ethoxy Carboxyl)Ethyl 0,0-Dimethyl Phosphorodithionate in
Punjab Soils," Indian J. Appl. Chem., 34(5):201-207 (1971).
2/ Nayshteyn, S. Y., V. A. Zhulinskaya, and Y. M. Yurovskaya, "The
Stability of Certain Phosphororganic Pesticides in the Soil,"
Gig. Sanit.. 38(7):42-45 (1973).
3_/ Galley, D. J., "Persistence of Some Organo-Phosphorus Insecticides
in Hen-House. Litter," Pest. Sci., 3(1):19-23 (1972).
4/ Kearney, P. C., and C. S. Helling, "Reactions of Pesticides in
Soils," Residue Rev.. 25:25-44 (1969).
163
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Field and Combined Field-Laboratory Studies - Roberts et al. (1962)—
studied the persistence of malathion (and other insecticides) in soil in
Georgia. Malathion was applied at an exaggerated rate of 76.6 Ib AI/
acre, followed by repeated annual applications of 16 Ib Al/acre in the
next 2 years. No malathion residues were detected in the soil after the
first year, nor after the second and third annual applications.
2/
Laygo and Schulz (1963)— reported that malathion applied to soil
persisted for 2 days.
3 /
Lichtenstein and Schulz (1964)V applied malathion at 5 Ib Al/acre
to Carrington silt loam field plots. Malathion was the least stable of
three organophosphate insecticides tested. Only 15% of the applied
dose could be recovered 3 days after application. After four addi-
tional days, 95% of the quantity applied had disappeared. A residue
level of malathion of approximately 0.1 ppm (3.1% of the applied dosage)
was reached under field conditions within 8 days.
Monitoring Studies - In the National Soils Monitoring Program for Pes-
ticides, 1,729 samples of cropland soils from 43 states were collected
in 1969 (Wiersma et al., 1972—'). Of these, 66 samples were analyzed
for organic phosphate residues, and two of these (3%) contained mala-
thion residues ranging from 0.04 to 0.36 ppm. The mean malathion resi-
due level was 0.01 ppm. One hundred and ninety-nine samples of non-
cropland soil were also obtained, but none of these were analyzed for
organophosphate residues.
I/ Roberts, J. E., R. D. Chisholm, and I,. Koblitsky, "Persistence of
Insecticides in Soil and Their Effect on Cotton in Georgia,"
J. Econ. Entomol., 55(2) (1962).
21 Laygo, E. R., and J. T. Schulz, "Persistence of Organophosphate In-
secticides and Their Effects on Microfauna in Soils," Proc. North
Dakota Acad. Sci.. 17:64-65 (1963). Quoted from Pimentel (1971).
3_/ Lichtenstein, E. P., and K. R. Schulz, "The Effects of Moisture and
Microorganisms on the Persistence and Metabolism of Some Organo-
phosphorus Insecticides in Soils, with Special Emphasis on Para-
thion," J. Econ. Entomol.. 57:618-627 (1964).
4/ Wiersma, G. B., W. G. Mitchell, and C. L. Stanford, "Pesticide Res-
idues in Onions and Soil - 1969," Pest. Monit. J., 5(4):345-347
(March 1972).
164
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In the National Soils Monitoring Program for Pesticides in 1970
(Crockett et al., 1970— ), soil and crop samples were collected from
1,506 cropland sites in 35 states. Pesticide use records indicated
that malathion was used at 84 (6.24%) "of the 1,346 sites sampled. No
analyses of soil samples for malathion residues are reported. Samples
of alfalfa, field corn kernels, cotton -stalks and green bolls, grass
hay, field corn stalks, cotton seeds, mixed hay, and soybeans (beans)
were analyzed for organophosphate residues. Malathion residues were
found in four of 18 (22%) samples of cotton stalks and green bolls,
ranging from 0.08 to 2.17 ppm, mean 0.16 ppm.. Minute residues of
malathion (mean less than 0.01 ppm) were also detected in one of 47
(2%) samples of grass hay, and in one of 270 (0.47o) samples of field
corn stalks.
In 1969, Wiersma et al. (1972) monitored pesticide residues in
commercially grown onions and in the soil on which these onions were
grown. A total of 76 sites in 10 major onion-producing states were
sampled. According to pesticide use records, malathion had been used
on 13.6% of the farms sampled, at an average rate of 2.86 Ib Al/acre.
No residues of malathion were found in any of the soil or onion samples.
2/
Stevens et al. (1970)— reported on a pilot monitoring study con-
ducted nationwide at 51 locations in 1965, 1966, and 1967 to determine
pesticide residue levels in soil. Samples were collected from 17 areas
in which pesticides were used regularly, 16 areas with a record of at
least one pesticide application, and 18 areas with no history of pesti-
cide use. Pesticide use records indicated that malathion had been used
at a number of the sites sampled, but only one single detection of a
malathion residue is reported, i.e., 0.03 ppm in the soil in one of five
fields sampled in Weld County, Colorado. Use records for this field did
not show any malathion applications.
I/ Crockett, A. B., G. B. Wiersma, H. Tai, W. G. Mitchell, and P. J.
Sand, "National Soils Monitoring Program for Pesticide Residues -
FY 1970," U.S. Environmental Protection Agency, Technical Services
Division, unpublished manuscript (1970).
2_/ Stevens-, L. J., C. W. Collier, and D. W. Woodham, "Monitoring Pesti-
cides in Soi'ls from Areas of Regular, Limited, and No Pesticide
Use," Pest. Monit. J., 4(3):145-164 (December 1970).
165
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The California Department of Water Resources (1969, 1970)izA' re-
ported on the pesticide concentrations in surface and subsurface drain
effluents in the San Joaquin Valley. In 1969, 14 samples of surface
and 41 samples of subsurface drain effluents were analyzed for organo-
phosphate compounds. No malathion residues were detected in any of
these samples. In 1970, 18 samples of surface and 60 samples of
subsurface drain effluents were analyzed for organophosphates. No
malathion residues were detected.
Since the results of the 1972 National Soils Monitoring Program
have not yet been published, more recent data was not included in
this review.
The scientific data on the residues and fate of malathion in the
soil from laboratory, field and monitoring studies reviewed show that
malathion is rapidly degraded in the soil. There appears to be some
disagreement among investigators on the relative contributions of
chemical vs microbiological processes to this degradation. However,
all data reviewed indicate that malathion residues in the soil are
short-lived. Kearney (1969), in a recent summary of pesticide per-
sistence data, states that malathion normally persists in soil for
about 1 week.
Residues in Water
Reviews - Recent general reviews on the fate of organophosphate and
other pesticides in water include those by Paris and Lewis (1973).£/
who discussed the chemical and microbial degradation of 10 selected
prsticides in aquatic systems; and by Faust and Suffet (1966)—' on the
recovery, separation, and identification of organic pesticides from
I/ California Department of Water Resources, "San Joaquin Valley Drain-
age Monitoring Program, 1969 Summary," Sacramento, California
(1969). In: Li and Fleck (1972).
2/ California Department of Water Resources, "San Joaquin Valley Drain-
age Monitoring Program, 1970 Summary," Sacramento, California
(1970). In: Li and Fleck (1972).
3/ Paris, D. F., and D. L. Lewis, "Chemical and Microbial Degradation
of Ten Selected Pesticides in Aquatic Systems," Residue Rev.,
45:95-124 (1973).
4/ Faust, S. D., and I. H. Suffet, "Recovery, Separation, and Identi-
fication of Organic Pesticides from Natural and Potable Waters,"
Residue Rev., 15:44-114 (1966).
166
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natural and potable waters. Furthermore, Chesters and Konrad (1971)—'
summarized the state of the art concerning the effects of pesticide
usage on water quality in a brief review article, drawing on a consid-
erable number of literature references. All of these are good summaries
of the state of the art in the fields indicated, but contain relatively
little specific detail on malathion.
2 /
Laboratory and Field Studies - Eichelberger and Lichtenberg (1971)—'
investigated the persistence of malathion and a number of other common
pesticides in raw river water over an 8-week period. Aliquots of 10
ug/liter of malathion from a freshly prepared 0.170 solution in acetone
were injected into samples of raw water from the Little Miami River, a
relatively small stream receiving domestic and industrial wastes and
farm runoff. The dosed raw river water was kept in the laboratory in
closed glass containers at room temperature, exposed to natural and
artificial light. Under these conditions, 25% of the original concen-
tration of malathion remained after 1 week, 10% after 2 weeks, zero
after 4 weeks. The same concentration of malathion was added to dis-
tilled water in the same manner in another test. Malathion remained
stable in distilled water for 3 weeks. The authors believe that this
indicates probable occurrence of a biological reaction in the raw river
water, but point out that this was not proved conclusively.
3/
At a recent scientific meeting, Wolfe et al. (1974)—' reported that
malathion can form relatively persistent and possibly toxic degradation
products in water. Laboratory tests showed that malathion breaks down
in water by two competing pathways, one yielding compounds that are con-
sidered nontoxic to aquatic organisms. The second pathway, which is
favored in colder water (35°F), results in the formation of malathion
Chesters, G., and J. G. Konrad, "Effects of Pesticide Usage on Water
Quality," Bioseience, 21(12):565-569 (1971).
Eichelberger, J. W., and J. J. Lichtenberg, "Persistence of Pesti-
cides in River Water," Environ. Sci. Technol., 5(6):541-544 (1971).
Wolfe, N. L., R. G. Zepp, G. L. Baughman, and J. A. Gordon, "Kinetic
Investigation of Malathion Degradation in Water," paper presented
at the 167th National Meeting of the American Chemical Society,
Division of Pesticide Chemistry, Los Angeles, California (1974).
167
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acids which may possess some of the toxic properties of malathion and
appeared to be moire persistent in the environment than the parent com-
pound. The acid hydrolysis of malathion is five orders of magnitude
slower, even at pH 5, acid hydrolysis is too slow to compete with basic
hydrolysis. Photochemical studies indicate that degradation of mala-
thion by direct sunlight photolysis would occur at a rate too slow to
be environmentally significant. At pH 8 and 28°C, malathion had a half-
life in water of about 1 month. The lifetime of malathion in water can
vary from several days to several months, depending upon temperatures
and other environmental conditions.
Konrad et al. (1969) studied the effect of pH on malathion degra-
dation in aqueous systems. In 7 days, malathion degraded 100% at pH
11, 25% at pH 9, 0% at pK 6, 4, and 2.
Lewis and Eddy (1959)— applied malathion (from an emulsifiable
formulation) at 1, 3, and 6 Ib Al/surface acre to log ponds for the
control of mosquito larvae in the vicinity of Corvallis, Oregon. Under
these conditions, malathion provided protection against mosquito rein-
festation for 2.5 to 6 weeks.
Guerrant et al. (1970).?/ measured environmental residues of
malathion after an aerial ULV application. Malathion low-volume con-
centrate (95%) was applied at the rate of 3.0 fl oz/acre. The amount
of malathion deposited on the surface in the treated area was determined
by measuring the amount found on exposed filter papers; the average con-
centration found was 1.5 mg/sq ftj or 65% of the applied dosage. The
I/ Lewis, L. F., and G. W. Eddy, "Control of Mosquito Larvae in Log
Ponds in Oregon," J. Econ. Entomol., 52:259-260 (1959).
2/ Guerrant, G. 0., L. E. Fetzer, Jr., and J. W. Miles, "Pesticide
Residues in Hale County, Texas, Before and After Ultra-Low
Volume Aerial Application of Malathion," Pest. Monit. J.,
4(1):14-20 (1970).
168
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maximum concentration found in environmental waters was 0.5 ppm mala-
thion. This concentration degraded with a half-life ranging from 0.5
to 10 days, depending primarily upon water pH.
Lenon et al. (1972)— measured insecticide residues in water and
sediments from cisterns on the U.S. and British Virgin Islands in 1970.
Malathion is used extensively on these islands for insect control pur-
poses. Malathion residues were found in only two of 49 water samples
analyzed, at very low concentrations (0.14 and 0.01 ppb, respectively).
However, evidence of an unknown malathion metabolite was found in all
49 water samples. This metabolite was not chemically identified; there-
fore, the importance of its presence could not be interpreted. Its de-
tection is reported to suggest the previous presence of its precursor,
malathion, in all samples, consistent with its extensive use in the area.
Rueckert and Ghelberg (1971)-' reported that malathion emulsions
stimulated oxygen consumption by 50 to 60% when added to slightly pol-
luted river water at 3 to 4 mg/liter, while oxygen production was
scarcely affected. At high concentrations, malathion inhibited oxygen
production completely. When the insecticide-dosed water samples were
stored, the inhibitory effects decreased. These studies were conducted
at the Sanitary Health Research Institute at Cluj, Rumania. In a report
from the same Institute, Nagy et al. (1971)3-/ described laboratory inves-
tigations on the persistence of malathion (and several other pesticides)
in water. Malathion was added to water at pH 5 to 5.5 in concentrations
of 0.2 to 150 mg/liter. Malathion was the least persistent among the
chemicals studied (7 to 21 days). Conversely, when odor thresholds were
studied, malathion was most persistent (21 days), while the odors of
other organophosphate insecticides persisted for only 5 to 10 days.
I/ Lenon, H., L. Curry, A. Miller, and D. Patulski, "Insecticide Resi-
dues in Water and Sediment from Cisterns on the U.S. and British
Virgin Islands," Pest. Monit. J., 6(3):188-193 (December 1972).
2/ Rueckert, I., and N. Ghelberg, "Experimental Investigation into the
Influence of Some Organic-Phosphorus Insecticides on the Oxygen
Content of Water," Deut. Gewaesserk. Mitt., 15(1):16-23 (1971).
3/ Nagy, S., R. Tomus, and N. Chelberg, "Laboratory Investigations into
the Persistence in Water of Some Pesticides of Phosphate Ester
Nature," Egeszsegtudomany, 15:65-73 (1971).
169
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Jirik et al. (1971)— studied the degradation of malathion in sur-
face water. When malathion was added to environmental water containing
a natural microbial population at a concentration of 10 ppm, it degraded
almost completely within 10 days. The microflora present in the water
participated in the decomposition of malathion, and there was no evi-
dence of any change in the microflora due to the presence of malathion.
Greve (1972)J/ reported that residues of malathion were identified in
water of the Rhine River in Germany at 0.01 to 0.1 ppb.
The data reviewed in this subsection indicate that malathion resi-
dues in water are degraded rather rapidly. In practically all experi-
ments reviewed, residues of malathion in water degraded more rapidly
than those of other pesticides studied under the same experimental con-
ditions. The very recent findings by Wolfe et al. (1974) concerning
the formation of more stable metabolites from the degradation of mala-
thion in water emphasizes the desirability of obtaining more informa-
tion on the chemical nature and the biological properties of the degra-
dation products of malathion (as well as of many other pesticides).
Monitoring Data - A number of agencies are listed in the Federal Environ-
mental Monitoring Directory (Council on Environmental Quality, 1973—')
with the indication that they conduct monitoring studies on pesticides
in water and/or aquatic organisms. All of these agencies were con-
tacted, but none of them were able to supply data on malathion residues
in water or aquatic organisms.
I/ Jirik, V., J. Pokorny, and H. Culikova, "Investigation of the Degra-
dation of the Organophosphate Insecticide Fosfotion in Surface
Water," Cesk. Hyg.. 16(6):177-182 (1971).
2/ Greve, P. A., "Toxic Organic Trace Pollutants in Surface Water,"
Chem. Weekbl., 41(68):11,13,15 (1972).
3_/ Council on Environmental Quality, The Federal Environmental Monitor-
ing Directory, U.S. Government Printing Office, Washington, D.C.
(1973).
170
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Residues in Air
Harris and Liechtenstein (1961)- exposed caged vinegar flies (Droso-
phila melanogaster) and houseflies (Musca domes tica.) to vapors from
quartz sand treated with malathion at the rate of 4 ppm. There was no
mortality among insects of either species that were kept in screened
cages above the malathion-treated sand for periods of 6 or 24 hr. Under
the same conditions, 100% mortality of the test insects was obtained
with several other-insecticides, demonstrating the validity of the method,
?/
Hopkins (1967)— studied the effects of humidity on the persistence
of malathion residues on leaf surfaces. The upper surfaces of the two
primary leaves of 2- to 3-week old bean plants were treated with mala-
thion at the rate of 400 ug/leaf. During the first 5 hr after treatment,
relative humidity over a range of 45 to 85% had no significant effect on
the rate of disappearance of malathion deposits from the leaf surfaces.
The authors concluded that volatilization by moving air currents and ab-
sorption by the leaf cuticle were not significantly affected by the rela-
tive humidity of the air during the initial period when the superficial
layers of the malathion deposit were more susceptible to loss. As the
residue diminished and became stabilized on the plant surface after the
first half-life, humidity began to exert a detectable effect.
o /
Alessandrini and Amormino (1954)- determined the volatility of
malathion and several other insecticides. Two milliliters of a 1% solu-
tion of malathion in ethyl ether were placed on a 4-in. watch glass.
The ether was allowed to evaporate, and the residues were maintained at
I/ Harris, C. R., and E. P. Lichtenstein, "Factors Affecting the Vola-
tilization of Insecticidal Residues from Soils," J. Econ. Entomol.,
54(5)-.1038-1045 (1961).
2_/ Hopkins, T. L., "Humidity Effects on the Persistence of Malathion
Leaf-Surface Residues," J. Econ. Entomol., 60(4):1167-1168 (August
1967).
3_/ Alessandrini, M. E., and V. Amormino, "Comparative Determinations of
the Volatility of Some Organic Phosphorus Insecticides," Inter-
national Symposium on Control of Insect Vectors of Disease,
pp. 93-96 (1954).
171
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a constant temperature of 35°C for a period of 90 days. Under these
conditions, malathion'was the least volatile among the organophosphate
insecticides studied. Its weight loss after 15 days ranged from 0 to
7.57. and 41 to 49% after 90 days. Three different grades of malathion,
i.e., pure grade 99.5%, technical grade 95%, and technical grade 86 to
90%, were included in these tests. The purest malathion sample exhib-
ited the lowest volatility.
Stanley et al. (-1971)— conducted a pilot study to establish a
system for measuring the extent of atmospheric contamination of the air
by pesticides in nine localities throughout the United States. Samples
were analyzed for 19 pesticides and metabolites, including malathion.
Malathion was found in only one of the nine sampling locations, i.e.,
Orlando, Florida. At that location, four samples of 99 analyzed con-
tained detectable amounts of malathion. The maximum level found was
2.0 ng/m3 of air.
Truhaut (1971)— discussed the problems surrounding the establish-
ment of maximum allowable concentrations of toxic substances in air in
the occupational environment, and the application of this concept to
community air pollution. Complexities involved include different ana-
lytical techniques, the instability of certain compounds, as well as
divergent interpretations of the same basic data in different countries.
As an example, the author mentions that industrial hygiene authorities
in the United States have established a maximum allowable concentration
of malathion in air at 15 mg/m3, whereas in the USSR, this value is 0.5
mg of malathion per cubic me'ter.
No further reports were found on the origin, presence, persistence,
and significance of malathion residues in air.
Residues in Nontarget Plants
No reports were found on the metabolism, or on residues of malathion
in or on nontarget higher plants.
I/ Stanley, C. W., J. E. Barney II, M. R. Helton, and A. R. Yobs,
"Measurement of Atmospheric Levels of Pesticides," Environ. Sci.
Techno1., 5(5):430-435 (1971).
2/ Truhaut, R., "The Problem of Maximum Allowable Concentrations of
Air Pollutants," Prod. Probl. Pharm., 25(8):530-548 (1971).
172
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Bioaccumulation, Biomagnification
No information dealing directly with the possible bioaccumulation
or biomagnification of malathion was obtained. However, the physical,
chemical, and biological properties of malathion make it most unlikely
that biomagnification in food chains or food webs occurs, and there is
no evidence that it does.
Metcalf (1972)— states: "Both the organophosphates and carbamates
are not persistent in soil and do not accumulate in body fat."
Environmental Transport Mechanisms
The data reviewed in the preceding subsections of this report sec-
tion indicate that under field conditions, malathion is rapidly de-
graded by chemical as well as by biological mechanisms. A majority of
the experimental data indicate that chemical degradation is most impor-
tant under field conditions. Several reports indicate that volatiliza-
tion does not appear to be a major transport mechanism by which mala-
thion may move away from target sites after application.
The propensity of malathion was determined for volatilization and
leaching under simulated field conditions for loam soils at 25°C at an
annual rainfall of 59 in. (150 cm) ivon Rumker and Horay, 19722/).
Volatilization of pesticides under these conditions, i.e., from a porous,
sorptive medium (loam soil) in a nonequilibrium situation, is different
from volatilization from an inert surface or from the chemical*s own
surface. Therefore, the environmental volatilization index assigned to
pesticides studies in this manner may or may not parallel a chemical's vapor
pressure. By this method, malathion rated a volatilization index of 2, in-
dicating an estimated median vapor loss from treated areas of 1.8 lb/acre/
year. This index number indicates that the propensity for volatilization
of malathion from treated fields is in the intermediate range, compared to
many other pesticides.
Leaching index numbers for pesticides indicate the approximate
distance that the chemical would move through the standardized loam
I/ Metcalf, R. L., "DDT Substitutes," Grit. Rev. Environ. Contr., 3(1)
25-59, Ref. 110 (1972).
2_/ von Rumker, R., and F. Horay, Pesticide Manual, Vol. I, Department
State, Agency for International Development (1972).
173
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soil profile under an annual rainfall of 59 in. (150 cm). Under these
conditions, malathion rated a leaching index number of 2 to 3, indicating
movement of 6 to 10 in.
It appears that under field conditions, malathion residues are
unlikely to migrate through ecosystems by environmental transport mech-
anisms to any significant extent. Malathion, after more than 20 years
of use for a variety of pest control purposes, has produced no apparent
adverse effects on the environment or man.
174
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References
Abdelrahman, I., "Toxicity of Malathion to the Natural Enemies of
California Red Scale, Aonidiella aurantii (Hemiptera:Diaspididae),"
Aust. J. Agr. Res., 24(1):119-133 (1973).
Alabaster, J. S., "Survival of Fish in 164 Herbicides, Insecticides,
Fungicides, Wetting Agents and Miscellaneous Substances," Int. Pest.
Control, ll(2):29-35 (1969).
Alessandrini, M. E., and V. Amormino, "Comparative Determinations of
the Volatility of Some Organic Phosphorus Insecticides," International
Symposium on Control of Insect Vectors of Disease, pp. 93-96 (1954).
Anderson, B. G., "The Toxicity of Organic Insecticides to Daphnia," in
Transactions of the Second Seminar on Biological Problems in Water
Pollution, Cincinnati, Ohio, U.S. Public Health Service, pp. 94-95
(1959). In: Li and Fleck (1972).
Anderson, J. P- E., "Factors Influencing Insecticide Degradation by a
Soil Fungus, Mucor alternans," Piss. Abstr. Int.. 32(6):3114B-3115B
(1971).
Anderson, L. D., and E. L. Atkins-, Jr., "Toxicity of-Pesticides to
Honey Bees in Laboratory and Field Tests in Southern California,
1955-1956," J. Econ. Entomol., 51:103-108 (1958).
Anderson, L. D., and T. 0. Tuft, "Toxicity of Several New Insecticides
to Honey Bees," J. Econ. Entomol., 45:466-469 (1952).
Bejer-Petersen, B., R. R. Hermansen, and M. Weihe, "On the Effects of
Insecticide Sprayings in Forests on Birds Living in Nest Boxes," Dan.
Ornithol. Foren. Tidsskr.. 66(1,2):30-50 (1972).
Bender, M. E., "Toxicity of the Hydrolysis and Breakdown Products of
Malathion to the Fathead Minnow (Pimephales promelas)," Water Res.,
3(8):571-582 (1969).
Beran, F., and J. Neururer, "The Action of Plant Protectants on the
Honey Bee (Apis mellifera). I. Toxicity of Plant Protectants to
Bees," Pflanzenschutz Ber., 15:97-147 (1955).
175
-------
Beran, F., and J. Neururer, "Actions of Plant Protectants on the Honey.
Bee (Apis mellifera). II. Toxicity of Plant-Protection Agency to
Bees," Pflanzenschutz Ber., 17:113-190 (1956).
Bowman, B. T., "The Effect of Water Upon Malathion Adsorption Onto Five
Montmorillonite Systems," Piss. Abstr. Int.. 31(3):1005B-1006B (1970).
Bowman, B. T., R. S. Adams, Jr., and S. W. Fenton, "Effect of Water
Upon Malathion Adsorption Onto Five Montmorillonite Systems," J. Agr.
Food Chem., 18(4):723-727 (1970) .
Burke, H. R., "Toxicity of Several Insecticides to Two Species of Bene-
ficial Insects on Cotton," J. Econ. Entomol., 52:616-618 (1959).
Butcher, J. W., J. Truchan, R. Wilson, and J. Fahey, "Streams Sampling
for Evidence of Pesticide Effects on Aquatic Arthropods," Proc. N.C.
Branch. Entomol. Soc. Amer.. 19:130-132 (1964).
California Department of Water Resources, "San Joaquin Valley Drainage
Monitoring Program, 1969 Summary," Sacramento, California (1969).
In: Li and Fleck (1972).
California Department of Water Resources, "San Joaquin Valley Drainage
Monitoring Program, 1970 Summary," Sacramento, California (1970).
In: Li and Fleck (1972).
Carter, F. L., and J. B. Graves, "Measuring Effects of Insecticides on
Aquatic Animals," LA Agr., 16(2):14-15 (1973).
Chesters, G., and J. G. Konrad, "Effects of Pesticide Usage on Water
Quality," Bioscience. 21(12):565-569 (1971).
Chopra, S. L., and K. C. Girdhar, "Persistence of Malathion S-1,2-bis
(Ethoxy Carboxyl)Ethyl 0,0-Dimethyl Phosphorodithionate in Punjab
Soils," Indian J. Appl. Chem.. 34(5):201-207 (1971).
Christie, A. E., "Effects of Insecticides on Algae," Water Sewage Works,
116(5):172-176 (1969).
Cope, 0. B., "Contamination of the Freshwater Ecosystem by Pesticides,"
J. Appl. Ecol., 3(Suppl):33-44 (1966). In: Li and Fleck (1972).
Coppage, D. L., "Effects of Malathion on Estuarine Organisms," unpub-
lished data (1974).
176
-------
Coppage, D. L., and T. W. Duke, "Effects of Pesticides in Estuaries
Along the Gulf and Southeast Atlantic Coasts," Proc. of the 2nd Gulf
Coast Conference on Mosquito Suppression and Wildlife Management,
pp. 26-30 (1971).
Council on Environmental Quality, The Federal Environmental Monitoring
Directory, U.S. Government Printing Office, Washington, D.C. (1973).
Crockett, A. B., G. B. Wiersma, H. Tai, W. G. Mitchell, and P. J. Sand,
"National Soils Monitoring Program for Pesticide Residues - FY 1970,"
U.S. Environmental Protection Agency, Technical Services Division,
unpublished manuscript (1970).
Culley, D. C., and H. G. Applegate, "Insecticide Concentrations in Wild-
life at Presidio, Texas," Pest. Monit. J., l(2):21-28 (1967).
Darsie, R. F., Jr., and F. E. Corriden, "The Toxicity of Malathion to
Killifish (Cyprinodontidae) in Delaware," J. Econ. Entomol., 52:696-
700 (1959).
Davis, H. C., and H. Hidu, "Effects of Pesticides on Embryonic Develop-
ment of Clams and Oysters, and on Survival and Growth of the Larvae,"
U.S. Fish Wildl. Serv.. Fish Bull., 67(2):393-404 (1969).
Drift, J., "Pesticides and Soil Fauna," Meded. Rijksfac. Landbouwwetensch.,
Gent, 35(2):707-716 (1970).
Eaton, J. G., "Chronic Malathion Toxicity to the Blueglll (Lepomis
macrochirus Rafinesque)," Water Res., 4:673-684 (1970).
Eichelberger, J. W., and J. J. Lichtenberg, "Persistence of Pesticides
in River Water," Environ. Sci. Technol.. 5(6):541-544 (1971).
Eisler, R., Jr., "Factors Affecting Pesticide-Induced Toxicity in an
Estuarine Fish," U.S. Bureau of Sport Fisheries and Wildlife Tech.
Paper No. 45, pp. 1-20 (1970).
Eisler, R., Jr., and M. P. Weinstein, "Changes in Metal Composition of
the Quahaug Clam, Mercenaria mercenaria, After Exposure to Insecti-
cides," Chesajeeake_Jcience_, 8(4):253-258 (1967).
177
-------
Faust, S. D., and I. H. Suffet, "Recovery, Separation, and Identifica-
tion of Organic Pesticides from Natural and Potable Waters," Residue
Rev., 15:44-114 (1966).
Federal Water Pollution Control Administration, "Water Quality Criteria,"
Report of the National Technical Advisory Committee, p. 37 (1968).
Galley, D. J., "Persistence of Some Organo-Phosphorus Insecticides in
Hen-House Litter," Pest. jSci.. 3(1): 19-23 (1972).
Garretson, A. L., and C. L. San Clemente, "Inhibition of Nitrifying
Chemolithotrophic Bacteria by Several Insecticides," J. Econ. Entomol.,
61(l):285-288 (1968).
Gaufin, A. R., L. D. Jensen, A. V. Nebeker, T. Nelson, and R. W. Teel,
"The Toxicity of Ten Organic Insecticides to Various Aquatic Inverte-
brates," Water Sewage Works, 12:276-279 (1965). In: Li and Fleck (1972)
Getzin, L. W., and I. Rosefield, "Organophosphorus Insecticide Degrada-
tion by Heat-Labile Substances in Soil," J. Agr. Food Chem., 16(4):
598-601 (1968).
Getzin, L. W., and I. Rosefield, "Partial Purification and Properties
of a Soil Enzyme That Degrades the Insecticide Malathion," Biochem.
Biophys. Acta, 235(3):442-453 (1971).
Giles, R. H., Jr., "The Ecology of a Small Forested Watershed Treated
With the Insecticide Malathion-35S," Wildlife Monographs, No. 24, 81
pages (1970).
Gorecki, K., "Harmful Effects of Insecticides Used in Poland on Apis
mellifica (Honey Bees)," Pol. Pismo Entomol., 43(1):201-210 (1973).
Greve, P- A., "Toxic Organic Trace Pollutants in Surface Water," Chem.
Weekbl., 41 (68): 11,13,15 (3»972) .
Guerrant, G. 0., L. E. Fetzer, Jr., and J. W. Miles, "Pesticide Residues
in Hale County, Texas, Before and After Ultra-Low Volume Aerial Appli-
cation of Malathion," Pest. Monit. J., 4(1):14-20 (1970).
Halvorson, H. M., Jr., M. Ishaque, Jr., J. Solomon, Jr., and 0. W.
Grussendorf, Jr., "A Blodegradability Test for Insecticides," Can.
J. Microbiol., 17(5):585-591 (1971).
178
-------
Hamilton, E. W., and R. W. Kieckhefer, "Toxicity of Malathion and Para-
thion to Predators of the English Grain Aphid," J. Econ. Entomol.,
62(5):1190-1192 (October 1969).
Hansen, D. J., "Avoidance of Pesticides by Untrained Sheepshead Minnows,"
Trans. Am. Fish. Soc., 98(3):426-429 (1969).
Hansen, D. J., J. M. Keltner, Jr., and S. Schimmel, "Avoidance of Pesti-
cides by Grass Shrimp (Palaemonetes pugio)," Bull. Environ. Contam.
Toxicol., 9(3):129-133 (1973).
Hansen, D. J., E. Matthews, S. L. Nail, and D. P. Dumas, "Avoidance of
Pesticides by Untrained Mosquitofish, Gambusia affinis," Bull. Environ.
Contam. Toxicol.. 8(1):46-51 (1972).
Harries, F. H., and A. C. Valcarce, "Laboratory Tests of the Effect of
Insecticides on Some Beneficial Insects," J. Econ. Entomol., 48:614
(1955).
Harris, C. R., and E. P. Lichtenstein, "Factors Affecting the Volatili-
zation of Insecticidal Residues from Soils," J. Econ. Entomol., 54(5):
1038-1045 (1961).
Heath, R. G., J. W. Spann, E. F. Hill, and J. F. Kreitzer, "Comparative
Dietary Toxicities of Pesticides to Birds," U.S. Bureau of Sport Fish-
eries and Wildlife, Special Scientific Report—Wildlife No. 152, pp.
1-40 (1972).
Henderson, C., "Little Wind Grasshopper Control Project, Wind River
Indian Reservation, Wyoming," U.S. Department of the Interior, Bureau
of Sport Fisheries and Wildlife, Pesticide Surveillance Program,
Special Report. 20 pages, 9 figures (1967a).
Henderson, C., "Podunk Grasshopper Control Project, Dixie National
Forest, Utah," U.S. Department of the Interior, Bureau of Sport
Fisheries and Wildlife, Pesticide Surveillance Program, Special
Report, 24 pages, 9 figures (1967b).
Hfll, E. F., D. A. Eliason, and J. W. Kilpatric, "Effects of Ultra-Low
Volume Applications of Malathion in Hale County, Texas," J. Med.
Entomol., 8(2):173-179 (1971).
Hilsenhoff, W. L./ "Toxicity of Granular Malathion to Walleyed Pike
Fingerlings." Mosquito News, 22:14-15 (1962).
179
-------
Hopkins, T. L., "Humidity Effects on the Persistence of Malathion Leaf-,
Surface Residues," "J. Econ. Entomol., 60(4):1167-1168 (August 1967).
Jensen, L. D., and A. R. Gaufin, "Effects of Ten Organic Insecticides on
Two Species of Stonefly Naiads," Trans. Am. Fish. Soc., 93:27-34
(1964a). In: Li and Fleck (1972).
Jensen, L. D., and A. R. Gaufin, "Long-Term Effects of Organic Insecti-
cides on Two Species of Stonefly Naiads," Trans. Am. Fish. Soc., 93:
357-363 (1964b). In: Li and Fleck (1972).
J;irik, V., J. Pokorny, and H. Culikova, "Investigation of the Degrada-
tion of the Organophosphate Insecticide Fosfotion in Surface Water,"
Cesk. Hyg.. 16(6):177-182 (1971).
Johansen, C. A., "Toxicity of Field-Weathered Insecticide Residues to
Four Kinds of Bees," Environ. Entomol., 1(3):393-394 (1972).
Johansen, C. A., and H. G. Davis, "Toxicity of Nine Insecticides to the
Western Yellowjacket," J. Econ. Entomol., 65(l):40-42 (1972).
Johansen, G. A., M. D. Levin, J. D. Eves, W. R. Forsyth, H. B. Busdicker,
D. S. Jackson, and L. I. Butler, "Bee Poisoning Hazard of Undiluted
Malathion Applied to Alfalfa in Bloom," Washington Agr. Exp. Sta.
Circular No. 455 (1965).
Joseph, S. R., J. Mallack, and L. F. George, "Field Applications of
Ultra-Low-Volume Malathion to Three Animal Species," Mosquito News,
32:504 (1972).
Katz, M., "Acute Toxicity of Some Organic Insecticides to Three Species
of Salmonids and to the Threespine Stickleback," Trans. Am. Fish. Soc.,
90(3):264-268 (1961).
Kearney, P. C., and C. S. Helling, "Reactions of Pesticides in Soils,"
Residue Rev., 25:25-44 (1969).
Kennedy, H. D., and D. F. Walsh, "Effects of Malathion on Two Warmwater
Fishes and Aquatic Invertebrates in Ponds," U.S. Bureau of Sport Fish-
eries and Wildlife Tech. Paper No. 55, 13 pages (1970).
Kerswill, C. J., and H. E. Edwards, "Fish Losses After Forest Spraying
with Insecticides in New Brunswick, 1952-1962, as Shown by Caged Speci-
mens and Other Observations," Fish Res. Board Can. J., 24(4):709-729
(1967).
180
-------
Konrad,.J. G., G. Chesters, and D. E. Armstrong, "Soil Degradation of
Malathion, a Phosphorodithioate Insecticide," Soil Sci. Soc. Amer.
Proc., 33(2):259-262 (1969).
Kowalska, T., and K. Szczepanska, "Toxicity to Entomophages of Some
Pesticides Used in Poland," Biul. Inst. Ochr. Rosl., 50:179-194
(1971).
Kutches, A. J., "Influence of Pesticides on Rumen Microbial Metabolism,"
Piss. Abstr. Int.. 31(5):2387B-2388B (1970).
Kutches, A. J., D. C. Church, and F. L. Duryee, "lexicological Effects
of Pesticides on Rumen Function in vitro," J. Agr. Food Ghent., 18(3):
430-433 (1970).
Laygp, E. R., and J. T. Schulz, "Persistence of Organophosphate Insecti-
cides and Their Effects on Microfauna in Soils," Proc. North Dakota
Acad. Sci., 17:64-65 (1963). Quoted from Pimentel (1971).
Lazaroff, N., "Algal Response to Pesticide Pollutants," Bacteriol. Proc.,
CI:48 (1967).
Lenon, H., L. Curry, A. Miller, and D. Patulski, "Insecticide Residues
in Water and Sediment from Cisterns on the U.S. and British Virgin
Islands," Pest. Monit. J.. 6(3):188-193 (December 1972).
Levin, M. D., W. B. Forsyth, G. L. Fairbrother, and F. B. Skinner,
"Impact on Colonies of Honey Bees of Ultra-Low-Volume (Undiluted)
Malathion Applied for Control of Grasshoppers," J. Econ. Entomol.,
61(l):58-62 (1968).
Lewallen, L. L., and W. H. Wilder, "Toxicity of Certain Organophosphorus
and Carbamate Insecticides to Rainbow Trout," Mosquito News, 22(4):
369-372 (1962).
Lewis, D. L., D. F. Paris, and G. L. Baughman, "Uptake and Transforma-
tion of Malathion by a Fungus, Aspergillus oryzae, Isolated from a
Freshwater Pond," submitted to Appl. Microbiol. (1974).
Lewis, L. F., and G. W. Eddy, "Control of Mosquito Larvae in Log Ponds
in Oregon," J. Econ. Entomol., 52:259-260 (1959).
181
-------
Li, M., and R. A. .Fleck, "The Effects of Agricultural Pesticides in the
Aquatic Environment, Irrigated Croplands, San Joaquin Valley," Pesti-
cide Study Series 6, Environmental Protection Agency, Office of Water
Programs, Applied Technology Division, Rural Waste Branch TS-00-72-05,
268 pages (1972).
Lichtenstein, E. P., and K. R. Schulz, "The Effects of Moisture and
Microorganisms on the Persistence and Metabolism of Some Organophos-
phorus Insecticides in Soils, with Special Emphasis on Parathion,"
J. Econ. Entomol., 57:618-627 (1964).
Lingren, P. D., D. A. Wolfenbarger, J. B. Nosky, and M. Diaz, Jr.,
"Response of Campoletis perdistinctus and Apanteles marginiventris
to Insecticides," J. Econ. Entomol., 65(5):1295-1299 (1972).
Liska, D., "Sanitary-Hygienic and Toxicological Problems of Pesticide
Residues in Some Spheres of the Environment," Lek. Obz., 29(1):11-15
(1971).
Macek, K. J., and W. A. McAllister, "Insecticide Susceptibility of Some
Common Fish Family Representatives," Trans. Am. Fish. Soc., 99(1):
20-27 (1970).
MacNamara, G. C., "Adsorption of Some Pesticides on Soils, Clay Minerals
and Humic Acid," Piss. Abstr., 29:2260B (1969).
MacNamara, G. C., and S. J. Toth, "Adsorption of Linuron and Malathion
by Soils and Clay Minerals," Soil Sci.. 109(4):234-240 (1970).
MacPhee, A. W., and K. H. Sanford, "Influence of Spray Programs on the
Fauna of Apple Orchards in Nova Scotia. X. Effects on Some Benefi-
cial Arthropods," Can. Entomol., 88:631-634 (1956).
Malacca, I., and M. lonescu, "Toxicity of Some Organophosphorus Insecti-
cides to Aquatic Organisms," Hidrobiologia, 10:31-41 (1969).
Manser, P. D., and F. D. Bennett, "Possible Effects of the Application
of Malathion on the Small Moth Borer, Diatraea saccharalis (F), and
Its Parasite Lizophaga diatraeae (Tns.) in Jamaica," Bull. Entomol.
Res.. 53:75-82 (1962/1963).
Markosyan, Z. K., "Effects of Pesticides on Bees Under Hothouse Condi-
tions," Mater. Sess. Zakavkaz. Sov. Koord. Nauch.-Issled. Rab. Zushch.
Rast.. pp. 688-690 (1968).
182
-------
Matida, Y., and N. Kawasaki, "Study on the Toxicity of Agricultural Con-
trol Chemicals in Relation to Freshwater Fisheries Management," No. 2,
Toxicity of Agricultural Insecticides to Daphnia carinata, King.
Bull. Freshwater Fish. Res. Lab., Tokyo, 8:1-6 (1958). In: Li and
Fleck (1972).
Matsumura, F., and G. M. Boush, "Malathion Degradation by Trichoderma
viride and a Pseudomonas Species," Science, 153(3741):1278-1280 (1966).
Matsumura, F., and G. M. Boush, "Metabolism of Insecticides by Micro-
organisms," Soil Biochem., 2:320-336, Marcel Dekker, New York (1971).
Mayland, P. G., and C. C. Burkhardt, "Honey Bee Mortality as Related to
Insecticide-Treated Surfaces and Bee Age," J. Econ. Entomol.-, 63(5):
1437-1439 (October 1970).
McEwen, L. C., C. E. Knittle, and M. L. Richmond, "Wildlife Effects from
Grasshopper Insecticides Sprayed on Short-Grass Range," J. Range Mgmt.,
25(3):188-194 (1972).
Metcalf, R. L., "DDT Substitutes," Grit. Rev. Environ. Contr., 3(1):
25-59, Ref. 110 (1972).
Meyers, N. L., J. L. Arlrichs, and J. L. White, "Adsorption of Insecti-
cides on Pond Sediments and Watershed Soils," Froc. Indiana Acad.
Sci., 79:432-437 (1970).
Moore, R. B., "Effects of Pesticides on Growth and Survival of Euglena
gracilis Z.," Bull. Environ. Contain. Toxicol., 5(3):226-230 (1970).
Morton, W. M., "Malathion Grasshopper Control Project on the Crow
Indian Reservation in Yellowstone and Big Horn Counties, Montana,"
U.S. Department of the Interior, Bureau of Sport Fisheries and Wild-
life, Pesticide Surveillance Program, Special Report, 10 pages, 8
figures, 4 tables (1966).
Mostafa, I. Y., I. M. I. Fakhr, M. R. E. Bahig, and Y. A. El-Zawahry,
"Metabolism of Organophosphorus Insecticides. XIII. Degradation of
Malathion by Rhizobium spp.," Arch. Mikrobiol., 86(3):221-224 (1972a).
Mostafa, I. Y., M. R. E. Bhig, I. M. I. Fakhr, and Y. Adam, "Metabolism
of Organophosphorus Insecticides. XIV. Malathion Breakdown by Soil
Fungi," Z. Naturforsch.. B 27(9):115-116 (1972b).
183
-------
Mount, D. I., and C. E. Stephan, "A Method for Establishing Acceptable
Toxicant Limits for Fish--Malathion and the Butoxyethanol Ester of
2,4-D," Trans. Am. Fish. Soc., 96:185-193 (1967).
Muncy, R. J., and A. D. Oliver, Jr., "Toxicity of Ten Insecticides to
the Red Crawfish, Procambarus clarki (Girard)," Trans. Am. Fish. Soc.,
92:428-431 (1963). In: Li and Fleck (1972).
Murphy, S. D., "Malathion Inhibition of Esterases as a Determinant of
Malathion Toxicity," J. Pharmacol. Exp. Ther., 156:352-365 (1967).
Nagvi, S. M., and D. E. Ferguson, "Levels of Insecticide Resistance in
Freshwater Shrimp, Palaemonetes kadiakensis," Trans. Am. Fish. Soc.,
99:696-699 (1970). In: Li and Fleck (1972).
Nagy, S., R. Tomus, and N. Chelberg, "Laboratory Investigations into the
Persistence in Water of Some Pesticides of Phosphate Ester Nature,"
Egeszsegtudomany, 15:65-73 (1971).
Nayshteyn, S. Y., V. A. Zhulinskaya, and Y. M. Yurovskaya, "The Stabil-
ity of Certain Phosphororganic Pesticides in the Soil," Gig. Sanit.,
38(7):42-45 (1973).
Nestor, I., "Influence of Organophosphorus Insecticides of the Malathion
and Bromofos Type on Gram-Positive Bacteria," Igiena. 20(12):723-730
(1972).
Paris, D. F., and D. L. Lewis, "Chemical and Microbial Degradation of
Ten Selected Pesticides in Aquatic Systems," Residue Rev., 45:95-124
(1973).
Paris, D. F., and D. L. Lewis, "Rates and Products of Degradation of
Malathion by Bacteria and Fungi from Aquatic Systems," presented at
the 167th National Meeting of the American Chemical Society, Division
of Pesticide Chemistry, Los Angeles, California (1974).
Paris, D. F., D. L. Lewis, and G. L. Baughman, "Rates of Degradation of
Malathion," unpublished manuscript, submitted to Environ. Sci. Technol.
(1974).
Parsons, J. K., and B. D. Davis, "The Effects on Quail, Migratory Birds,
and Nongame Birds from Application of Malathion and Other Insecti-
cides," Tech. Series No. 8, Texas Parks and Wildl. Dept., pp. 1-20
(1971).
184
-------
Peterle, T. J., and R. H. Giles, New Tracer Techniques for Evaluating
the Effects of an Insecticide on the Ecology of a Forest Fauna, Ohio
State Univ. Res. Found. Rep., 435 pages (1964).
Pickering, Q. H., C. Henderson, and A. E. Lemke, "The Toxicity of
Organic Phosphorus Insecticides to Different Species of Warmwater
Fishes," Trans. Am. Fish. Soc., 91(2):175-184 (1962).
Pimentel, D., "Ecological Effects of Pesticides on Nontarget Species,"
Executive Office of the President, Office of Science and Technology,
U.S. Government Printing Office, Washington, B.C. (1971).
Poorman, A. E., "Effects of Pesticides on Euglena gracilis. I. Growth
Studies." Bull. Environ. Contain. Toxicol.. 10(l):25-28 (1973).
Pradhan, S., M. G. Jotwani, Sarup, Prakash, "Bioassayof Different Insec-
ticides on the Important Insect Pests and Predators of Agricultural
Importance," Pest. Symp., pp. 92-103 (1968).
Priester, L. E., "The Accumulation in Metabolism of DDT, Parathion and
Endrin by Aquatic Food-Chain Organisms," Ph.D. thesis, Clemson Uni-
versity (1965). In: Li and Fleck (1972).
Randall, C. W., M. Asce, and R. A. Lauderdale, "Biodegradation of Mala-
thion," J. Sanit. Eng. Div., Proc. Amer. Soc. Civil Eng., 93(6):145-
156 (1967).
Ranke-Rybicka, B., "Viability of Tadpoles of Rana temporaria Intermit-
tently Exposed to Organophosphorus Pesticides (Phoschlor and Mala-
thion)," Roez. Panstw. Zakl. Hig., 23(3):37 (1972).
Ranke-Rybicka, B., and J. Stanislawska, "Changes in Periphyton Organ-
isms Caused by Organophosphorus Pesticides (Malathion, Phoschlor),"
Roez. Panstw. Zakl. Hig., 23(2):137-146 (1972).
Ridgway, R. L., C. B. Cowan, and J. R. Cage, unpublished data (personal
communication) (1974).
Roberts, J. E., R. D. Chisholm, and L. Koblitsky, "Persistence of Insec-
ticides in Soil and Their Effect on Cotton in Georgia," J. Econ. "
Entomol.. 55(2) (1962).
185
-------
Rueckert, I., and N'. Ghelberg, "Experimental Investigation into the
Influence of Some Organic-Phosphorus Insecticides on the Oxygen Con-
tent of Water," Deut. Gewaesserk. Mitt., 15(l):16-23 (1971).
Sanders, H. 0., "Toxicity of Pesticides to the Crustacean Gammarus
lacustris." U.S. Department of the Interior, Fish and Wildlife Service,
Technical Paper No. 25, p. 18 (1969).
-*t
A
Sanders, H. 0., "Pesticide Toxicities to "Tadpoles of the Western Chorus
Frog Pseudacris triseriata and Fowler's Toad Bufo woodhousii fowleri,"
Copeia. 2:246-251 (1970).
Sanders, H. 0., and 0. B. Cope, "Toxicities of Several Pesticides to
Two Species of Cladocerans," Trans. Am. Fish. Soc., 95 (2):165-169
(1966).
f
Sanders, H. 0., and 0. B. Cope, "The Relative Toxicities of Several
Pesticides to Naiads of Three Species of Stoneflies," Limnol. Oceanog.,
13(1):112-117 (1968).
Satpathy, J. M., G. K. Padhi, and D. N. Dutta, "Toxicity of Eight Insec-
ticides to the Coccinellid Predator Chilomenes sexmaculata." Indian
J. Entomol.. 30(1):130-132 (1968).
Satyanarayana, T., and L. W. Getzin, "Properties of a Stable Cell-Free
Esterase from Soil," Biochem., 12(8):1566-1572 (1973).
Sethunathan, N., and T. Yoshida, "Conversion of Parathion to Paranitro-
phenol by Diazinon-Degrading Bacterium," Proc. Inst. Environ. Sci.
Ann. Tech. Meet., 18:255-257 (1972).
Sreenivasan, A., and G. K. Swaminathan, "Toxicity of Six Organophos-
phorus Insecticides to Fish," Curr. Sci.. 36:397-398 (1967).
Sreenivasan, A., and R. R. Saundar, "Toxicity of Malathion and Parathion
to Fish," Symposium on Pesticides, Mysore, India, 1961, pp. 316-318
(1968).
Shea, K. P., "Dead Stream," Environment. 12(6):12-15 (1970).
Stanley, C. W., J. E. Barney II, M. R. Helton, and A. R. Yobs, "Measure-
ment of Atmospheric Levels of Pesticides," Environ. Sci.. Technol.,
5(5):430-435 (1971).
186
-------
Steelman, C. D., A. R. Colmer, L. Cabes, H. T. Barr, and B. A. Tower,
"Relative Toxicity of Selected Insecticides to Bacterial Populations
in Waste Disposal Lagoons," J. Econ. Entomol., 60(2):467-468 (1967).
Stevens, L. J., C. W. Collier, and D. W. Woodham, "Monitoring Pesti-
cides in Soils from Areas of Regular, Limited, and No Pesticide Use,"
Pest. Monit. J., 4(3):145-164 (December 1970).
Tagatz, M. E., P. W. Borthwick, G. H. Cook, and D. L. Coppage, "Studies
on Effects of Ground Applications of Malathion on Salt-Marsh Environ-
ments in Northwestern Florida," unpublished manuscript, submitted to
Mosquito News, 16 pages (1974).
Teetes, G. L., "Differential Toxicity of Standard/and Reduced Rates of
Insecticides to Greenbugs and Certain Beneficial Insects," Tex. Agr.
Exp. Sta., Progress Report No. PR-3041, 9 pages (1972).
Teotia, T. P. S., and G. C. Tiwari, "Toxicity of Some Important Insecti-
cides to the Coccinellid Predator, Coccinella septempunctata," Labdev,
Part B, 10(1):17-18 (1972).
Truhaut, R., "The Problem of Maximum Allowable Concentrations of Air
Pollutants," Prod. Probl. Pharm., 25(8):530-548 (1971).
Tucker, R. K., and D. G. Crabtree, Handbook of Toxicity of Pesticides to
Wildlife, Bureau of Sport Fisheries and Wildlife, Denver Wildlife Re-
search Center, Resource Publication No. 84, pp. 76-77 (1970).
von Riimker, R., and F. Horay, Pesticide Manual, Vol. I, Department of
State, Agency for International Development (1972).
Walker, W. W., and B. J. Stojanovic, "Microbial Versus Chemical Degrada-
tion of Malathion in Soil," J. Environ. Qual.. 2(2):229-232 (1973).
Walker, W. W. and B. J. Stojanovic, "Malathion Degradation by an
Arthrobacter Species," J. Environ. Qual., 3(1):4-10 (1974).
Wall, J., and V. M. Marganian, Jr., "Control of Culicoides melleus (Coq)
(Diptera:Ceratopogonidae) with Granular Organophosphorus Pesticides,
and the Direct Effect on Other Fauna," Mosquito News, 31(2):209-214
(1971).
Ware, G. W., and C. C. Roan, "Interaction of Pesticides with Aquatic
Microorganisms and Plankton," Residue Rev.. 33:15-45 (1971).
187
-------
Wellborn,!. L., "Toxicity of Some Compounds to Striped Bass Fingerlings,"
Prog. Fish Cult., 33(l):32-36 (1971).
Westman, J. R., and K. Compton, "Responses of Salt Marsh Killifishes to
Certain Environmental Changes and to Malathion," Proc. New Jersey
Mosquito Extermination Assoc., 47:116-123 (1960).
Wiersma, G. B., W. G. Mitchell, and C. L. Stanford, "Pesticide Residues
in Onions and Soil - 1969," Pest. Monit. J.. 5(4):345-347 (March 1972).
Wiese, I. H., "Toxicity of Modern Insecticides to the South African
Honey Bee," S. African Bee J., 32:2,7,9-10 and 3,6-7,9-10 (1957).
Wiese, I. H., "Toxicity of Modern Insecticides to the South African
Honey Bee," African' Beekeeping, 1:14-15 (1958a).
Wiese, I. H., "The Toxicity of Modern Insecticides to the South African
Honey Bee," S. African Bee J.. 32:4,5,7; 5,9-11; and 6,10-11 (1958b).
Wilson, B. R., "Fate of Pesticides in the Environment - A Progress
Report," Trans. New York, N.Y. Acad. Sci., 28:694-705 (1966). Quoted
from Pimentel (1971).
Wolfe, N. L., R. G. Zepp, G. L. Baughman, and J. A. Gordon, "Kinetic
Investigation of Malathion Degradation in Water," paper presented at
the 167th National Meeting of the American Chemical Society, Division
of Pesticide Chemistry, Los Angeles, California (1974).
188
-------
SUBPART II. D. PRODUCTION AND USE
CONTENTS
Page
Registered Uses of Malathion 190
Federally Registered Uses 190
State Regulations 213
Production and Domestic Supply of Malathion in the United States . 213
Volume of Production 213
Imports 217
Exports 217
Domestic Supply 218
Formulations 218
Use Patterns of Malathion in the United States 219
General 219
Agricultural Uses of Malathion 219
Farm Uses of Malathion by Regions 223
Farm Uses of Malathion by Crops 224
Industrial, Commercial, and Institutional Uses of Malathion. . . 225
Governmental Agencies' Uses of Malathion 225
Home and Garden Uses of Malathion 226
Malathion Uses in California 226
References 249
189
-------
This section contains data on the registered uses, and on the
production, domestic supply, and use patterns of malathion. The section
summarizes rather than interprets scientific data reviewed.
Registered Uses of Malathion
Federally Registered Uses - Malathion has a very broad spectrum of
effectiveness against insects and mites. It is registered and recom-
mended in the United States for use on about 130 different crops, on
livestock and pets, and on agricultural premises such as barns (including
dairy barns and milk rooms), feedlots, holding pens, poultry houses,
feed rooms, and grain bins. The foregoing count of 130 crops includes
several dozen minor vegetables counted as only one crop. Tolerances for
malathion residues have been established on at least 127 raw agricultural
commodities.
The registered uses of malathion by crops, established tolerances,
dosage rates, and use limitations are summarized in the EPA Compendium
of Registered Pesticides.±1.
The registered uses of malathion are detailed in this subsection
in a set of three tables as follows:
Table 26: Insect and mi.tie gests against which malathion is
recommended, in alphabetical order by common names, including scientific
names.
This table includes 97 entries. In order to keep it to a manageable
length, many individual species of target insects have been grouped to-
gether by genera, families, or even orders (examples: "aphids," "mites,"
"leafminers," etc.).
Table 27: Registered uses of three commonly used formulations of
malathion. The formulations used are: 57% emulsifiable liquid (5 Ib Al/gal);
25% wettable powder; and 4% dust. Table 27, taken from the manual of label
claims for malathion prepared by the American Cyanamid Company (the only basic
producer of malathion in the United States) and summarizes the registered uses
of the above three malathion formulations by crops; insects and other pests
controlled on each crop; recommended dosage rates; residue tolerances; and
general and specific directions for, and limitations of use.
I/ U.S. Environmental Protection Agency, EPA Compendium of Registered
Pesticides: Insecticides, Araricides, Molluscides and Anti-
Fouling Compounds, Vol. Ill (1973).
190
-------
Table 25. INSECT AND MITE PESTS AGAINST WHICH MALATHION
IS RECOMMENDED (in alphabetical order by common names)
Alafalfa caterpillar
Alafalfa looper
Alfalfa weevil
Ants
*Aphids
Armyworm
Asparagus beetle
Bagworm
Bed bug
Beet leafhopper
Birch leafminer
Blackheaded fireworm
Blueberry fruit fly
Body lice
Boxwood leafminer
Brown cotton leafworm
Brown dog tick
Cabbage looper
Carpet beetle
Cat flea
Caterpillars
Celery looper
Centipedes
Cereal leaf beetle
Cherry fruit fly
Cherry fruitwona
Chigger
Cigarette beetle
Cloths moths
Clover leaf weevil
Cockroaches
Codling moth
Confused flour beetle
Corn earworm
Corn rootworm
Cotton leafperforator
Cotton leafworm
Cranberry fruitworm
Cucumber beetle
Diamondback moth
Darkwinged fungus gnat
Dog flea
Driedfruit beetle
Colias eurytheme
AutogApha californica
Hypera postica.
Fmn-i 1 y Fonnicidae
Family Aphididae
Pseudaletia unipuncta
Crioceris asparagi
Thyridopteryx ephemeraefonais
Cimex lectularis
Cruculifer tenellus
Fenusa pus ilia
Rhopobota naevana
Rhagoletis mendax
Pediculus humanus humanus
Monarthropalpus buxT
Acontia dacia
Rhipicephalus sanguineus
Trichoplusia ni
Anthrenus scrophulariae
Ctenocephalides felis
Order Lepidoptera
Anagrapha falcifera
Class Chilopoda
Oulema melanopus
Rhagoletis cingulata
Grapholitha packardi
Family Trombiculidae
Lasioderma serricorne
Family
Hypera punctata
Order Dictyoptera
Lasperresia pomonella
Tribolium conf usum
Heliothis zea
Diabrotica spp.
Bucculatrix thurberiella
Alabama argillacea
Acrobasis vaccinii
Family Chrysomelidae
Plutella xylostella
Ctenocephalides canis
Carpophilus hemipterus
Refer to manufacturer labels for specific pest recommendations.
Source: American Cyanamid Co., CYTHION - Manual of Label Claims for Insect Control.
191
-------
Table 25. (Continued)
Drosophila
Earwigs
European pine sawfly
European pine shoot moth
Eyespotted budmoth
Fall armyworm
False chinch "bug
Flat grain beetle
Flea beetles
Fourlined plant bug
Fruit flies
Truittree leafroller
Garden webworm
Granary weevil
Grape phylloxera
Grasshoppers
Greenbugs
Green cloverworm
Greenhouse thrip
Green stink bug
Ground pearl
Harlequin bug
Head lice
Hemlock looper
Horn fly
Indian meal moth
Imported cabbage worm
Imported currentworm
Japenese beetle
Khapra beetle
Lace bugs
Larch casebearer
Leafhoppers
Lesser grain borer
Lesser peach tree borer
Lice
Lygus bugs
Mealybugs
Mediterranean fruit fly
Mexican bean beetle
Milipedes
#Mites
Morningglory leafminer
Mosquitoes
Nitidulid beetles
Northern fowlmite
Oak kerms
Qmniverous leaftier
Omniverous looper
Onion maggot
Orange tortrix
Family Drosophilidae
Family Dermaptera
Neodiprion sertifer
Rhyacibriia buoliana
Spilonota ocellana
Spbdoptera frugiperda
Nusius ericae
Cryptolestes pusillus
Family Chrysomelidae
Poecilocapsus lineatus
Family Tephritidae
Archipes argyrospilus
Loxostege rantalis
Sitophilus granarxus
Phylloxera" vitifoliae
Family Acrididae
Aphididae
Plathypena scabra
Heliothrips haemorrhoidalis
Acrosternum hilare
Family Margarodidae
Margantia histrionica
Pediculus humanus capitis
Lambdina fiscellaria
Haematobia irritans~
Plodia interpunctella
Pieris rapae
Nematu's ribesii
Popillia japonica
Trogoderma granarium
Family Tingidae
Coleophora laricella
Family Cicadellidae
Rhyzopertha dominiea
Synanthedon pictipes
Orders Anoplura/Mallophaga
Lygus spp.
Family Pseudococcidae
Ceratitis capitata
Epilachna" varivestis
Class Diplopoda ,
Order Acarina
Bedellia somnulentella
Family Culicidae
Family Nitidulidae
Ornithonyssus sylvarum
Kermes pubescens
Cnephasis longana
Sabulodes caberata
Hylemya antiqua
Argyrotaenia citrana
192
-------
Table 25. (Continued)
Oriental fruit moth
Otodectic mange mites
Peach twig borer
Pea weevil
Pear psylla
Pecan bud moth
Pecan leaf casebearer
Pecan nut casebearer
Pecan phylloxera
Pepper maggot
Phorid flies
Pickleworm
Pi-inn curculio
Potatoe leafhopper
Redbanded leafroller
Red flour beetle
Rice leafminer
Rice stinkbug
Rice weevil
Rose leafhopper
Rusty grain beetle
Sap beetle
Saratoga spittlebug
Sarcoptic mange
Sawtoothed grain beetle
^Scales
Scorpions
Shaft lice
Sharpnosed leafhopper
Sheep ked
Silverfish
*Soft scales
Sorghum midge
Spiders
Spittlebugs
Spruce budworm
Squash vine borer
Strawberry leafroller
Strawberry root weevil
Sugarbeet root maggot
Tarnished plant bug
Tent caterpillar
Thrips
Ticks
Unspotted tentiform caterpillar
Vetch bruchid
Walnut husk fly
Western yellowstriped armyworm
Whiteflies
Yellownecked caterpillar
Grapholitha molesta
Otodectes spp.
Anarsia lineatella
Bruchus pisorum
Psylla pyricola
Gretchena bolliana
Acrobasis" juglandrs
Acrobasis nuxvorella
Phylloxera devastatrix
Zonosemata electa
Family Phoridae
Diaphania nitidalis
Conotrachelus nenuphar
Empoasca fabae
Argyrotaenia velutinana
Tribolium castaneum
Hydrellia griseola
pebalus pugnax
Lissorhoptrus oryzophilus
Edwardsiana rosae
Cryptolestes ferrugineus
Family Nitidulidae
Aphrophora saratogensis
Family Sarcoptidae
Oryzaephilus surinamensis
Superfamily Coccoidea
Order Scorpionida
Menopon gallinae
Scaphytopius magdalensis
Melophagus ovinus
Lepisna saccharina
Family Coccidae
Contarinia sorghicola
Order Araneida
Family Cercopidae
Choristoneura fumiferana
Mellittia cucurbitae
Ancylis comptana
Otiorhynchus ovatus
Tetanops myopaeformis
Lygus lineolaris
Malacosoma spp.
Order Thysanoptera
Order Acarina
Parornix geminatella
Bruchus "brachiali s
Rhagoletis completa
Spodoptera praefica
Family Aleyrodidae
Datana ministra
193
-------
Tab]o 26. REGISTERED USES, DOSAGE RATES, TOLERANCES, AMD USE LIMITATIONS FOR COMMONLY USED MALATHION FORMULATIONS
(57% emulnlftable concentrate, 25% wettable powder, and 4% dust)
VO
•is-
iwitcticiei
THE PREMIUM GRADE MALATHION
MANUAL
of
LABEL CLAIMS
for
INSECT CONTROL
f-'liilfffTTl'Tl i
TABLE
O F
CONTENTS
INSECT CONTROL WITH CYTHION 2
FIELD CROPS 4
FORAGE CROPS 6
VEGETABLES 8
FRUIT 12
BERRIES 18
NUTS 20
ORNAMENTALS 22
LIVESTOCK 24
POULTRY 26
PETS 28
HEAD AND BODY LICE ON HUMANS 29
HOMES, DAIRIES, FOOD PROCESSING PLANTS 29
DRY MILK PROCESSING PLANTS 33
STORED GRAINS AND PEANUTS 34
STORED PRODUCTS 36
MISCELLANEOUS 38
INDEX 40
' lii'l>'r''t
C YA JV A 1*X I
INSECT CONTROL WITH CYTHION' INSECTICIDE
THE PREMIUM GRADE MALATHION
A development of American Cyonamid Company. CYTHION* is the first in-
secticide to offer control of so many Insects, and at the same time to have
such a low hazard to man and animal. CYTHION controls a great diversity
of insects including aphids. spider mites, scales and house flics as well as •
wide range of other sucking and chewing insects attacking fruits, vegetables,
ornamentals and animals — a total of over one hundred insects on more than
ninety crops.
AMERICAN CYANAMID COMPANY • AGRICULTURAL DIVISION • P.O. BOX 400, PRINCETON, N. J. 08540
FORMULATIONS: American Cyanamid Company produces and sells CY-
THION The Premium Grade Malathion* which many well known manu-
facturers use to formulate emulsifiable liquids, wettable powders, dusts, and
pressurized sprays under their own brand names.
COMPATIBILITY: CYTHION is compatible in spray tank mixes with most
insecticides and fungicides: DDT, lead arsenate, methoxychlor. mineral oil,
TOE, CYPREX* Fruit Fungicide, ferbam. glyodin. captan. tribasic copper sul-
fate, sulfur, zincb, maneb, ziram. KARATHANE, dieldrin, aldrin, chlordane.
toxaphene, parathion, and other organic phosphates. There are no phyjoloxic
effects or decrease in effectiveness when CYTHION is used in these tank mix
combinations. Spray tank mixtures of CYTHION with alkaline insecticides
and fungicides should be applied promptly.
s
For proper mixing, the spray tank should be at least 3/4 filled with water
before CYTHION formulation is added. Mechanical agitation or recirculation
through the pump by-pass to the tank is usually sufficient for maintaining
a good dispersion.
Because uniform dispersibility and sprayability may be influenced by the
pesticide combinations used, it is recommended that compatibility be de-
termined before adding pesticides to the spray tank.
•O.O-dlmethyl phoiphorodlthloata of dlethyl mercaploiucclnau
'Registered Trademark of American Cyanamld Company
-------
Table 26. (Continued)
Ui
MIXING SMALL QUANTITIES: For mixing small quantities, use 1 teaspoon-
ful of emulsifiable liquid per gallon for each pint used per 100 gallons. Use 1
tablcspoonful of 25% wcttablc powder per gallon for each pound used per
100 gallons.
CYTHION USES: Uses for CYTHION that have been registered by the Pesti-
cides Regulation Division, U.S. Department of Agriculture, are shown in the
charts that follow.
When it Is necessary to observe special precautions, these are indicated under
the registered use.
NOTE: CYTHION may cause spotting on automobile paint finishes. Cars
should nqt be sprayed directly. If accidental exposure does occur, the car
should be washed immediately.
APPLICATION: Rates of application or concentration included in the follow-
ing tables are shown as 57% emulsifiable liquid, 25% wettable powder, or
4% dust. For ground applications on the crops listed, unless otherwise noted,
the specified amounts of the emulsifiable liquid or wettable powder should be
applied in sufficient water for good coverage, usually 25 to 50 gallons of water
per acre. Applications by aircraft should be made in 2 to 10 gallons of water
per acre. Do not make applications when winds exceed 5 miles per hour.
Repeat applications should be made as needed unless otherwise indicated.
Consult your Slate Experiment Station or State Agricultural Extension Service
for additional information as the number, rates, and timing of application
needed will vary with local conditions.
RESIDUES: Residue tolerances for CYTHION established by the Food and
Drug Administration are shown in the following tables. These tolerances are
established in accordance with the pre-harvest intervals which are also listed.
Those uses for which "NR" is indicated were previously "no residue" regis-
trations. Tolerances and intervals for these uses are subject to pending peti-
tions.
CROP
PEST
AMOUNT PER ACRE
57Z 25*
Emulsifiable, Wettable
Liquid ' Powder
'Interval (days)
between last
4% Residue application
Dust Tolerance and harvest
or gra»ln
COTTON
HOPS
MINT
Boll weevil
Desert spider
mite
Cotton aphid
Leafhoppers
White flies
Cotton leafworm
Brown cotton
leafworm
Cotton leaf
perforator
Thrips
Lygus bugs
Fleahoppers
Fall armywprms
Grasshoppers
Garden webworms
Aphids
Mites
Aphids
Spider mites
Leafhoppers
Adult flea
beetles
Caterpillars
1-2 qts.
For control o
combin
1-2 qts.
1-lV4pts.
ltt-3 pts.
—
•\Vi pts.
•\Vt pts.
1 worms am
ation with c
—
—
—
2lbs.
—
—
25-50 Ibs.
weevils, CYTH
ther recomme
10-25 Ibs.
10-25 Ibs.
25-50 Ibs.
—
—
25 Ibs.
2 ppm on
cotton
seed
ION should
rided insecti
2 ppm on
cotton
seed
2 ppm on
cotton
seed
2 ppm on
cotton
seed
NR
8 ppm
8 ppm
0
be used in
:ides.
0
0
0
10
7
7
-------
Table 26. (Continued)
E """"•' **•".» •-" "-" '•' -I!'" •!' • «• **,*,*.:••*••* --f «MF',--- "••
,**«u*U4>.u* , , >*^,t »«.fr--*\U*s^*fc"to' .' y ' ft .-^itLj— ujj**-
^.i^^^^aSH^SSia^j pIK
AMOUNT PER ACRE J;
Interval Ways)/ CROP
' 57% 25% between last £J
CROP PEST Bnulsifioble Wettable 4* Kesiaue application. •*
Liquid Powder Dust Tolerance and harvest ALFAL
•srf**d'—v±} r* **'-*v^*'/2-2pts.
For control o
temperatures
aCYTHO>H
Consu
—
1>/2-2pts.
1 Vz-2 pts.
Use higher dc
1 Vt pts.
Apply in sprin
1pt.
1 1/2-2 pts.
2 pts.
Make full cov
alfalfa wee
and for con
- methoxycl
It your loc;
—
—
>sage on tal
;whenalfa
• —
—
3lbs.
:rage applic
30 Ibs.
vil larvae und
trol of heavy
ilor combinat
I State Experi
30 Ibs.
12-20 Ibs.
er alfalfa.
fa is 2-6 inche
—
—
35 Ibs.
ation when la
135 ppm
er conditions
nfestations o
on may be pr
mcnt Station.
135 ppm
135 ppm
135 ppm
135 ppm
stall.
135 ppm
135 ppm
0
of low
splittlebug,
eferred.
0
0
0
0
0
0
135 ppm 0
rvae are small.
Apply to alfalfa in bloom only in the evening or earl
when bees are not work ng in the field or are not ha
outside of hives.
iyz-2pts.
iy2-2pts.
1 1/2 pts.
Apply in sprin
4lbs.
4 Ibs.
5 when clov
25-30 Ibs.
—
'er is 2-6 inchc
Do not apply to clover in bloom.
Grasshoppers
Aphids
Leafhoppers
1>/2-2pts.
OR
1 Vz pts. in
1 gal.diesil
fuel oil.*
Repeat applic
1>/2-2pts.
OR
1 1/2 pts. in
1 gal. dicsel
fuel oil.*
ations may
movemen
2 Ibs.
ie needed a'tt
to crops take
30-40 Ibs.
135 ppm
135 ppm
135 ppm
s tall.
135 ppm
Thatching an
s place.
135 ppm
•Apply by aircraft or turbine-blower sprayer.
f morning
nging on
0
0
-J)
0
d before
0
-------
Table 26. (ConLiuucd)
VO
-J
AMOUNT PER ACRE Interval (days)
between last
57* "* , „ jj application
CROP PEST Bnulsifiable Wettable M Residue d h
,^, Liquid Powder Dust Tolerance or ^^
CRASS CROPS
Crass &
Grass hay
Pasture &
Range
grass
f Barn grass
Canary
grass
Fescue
Orchard
grass
Red lop
Timolhy
Yellow
foxtail
GRAIN CROPS
Barley
Corn
OaU
VVhcal
Barley
Oats
Rye
Wheat
NON-AGRI-
CULTURAL
1 AN OS
(wastelands,
roadsides,
soil bank
lands not lo
be grazed)
•Arm/worms
2 pis.
OR
I'/z pts. in
1 gal. dicsel
fuel oil.'
3lbs.
Apply when
35-40 Ibs.
larvae are s
135 0pm
nail.
'Apply by aircraft or turbine-blower sprayer.
Grasshoppers
Aphids
I.ealhoppers
1'/2-2pts.
OR
IVi pis. in
1 gal. diesel
fuel oil.*
Repeal applic
1>/2-2pts.
OR
1 '/2 pts. in
1 gal. dicsel
fuel oil.*
alions may be
movement t
2lbs.
needed aft
o crops lake
30-40 Ibs.
135 ppm
er hatching a
s place.
135 ppm
'Apply by aircraft or turbine-blower sprayer.
Cereal leaf
beetle
Cereal leaf
beetle
Cn^l'sh grain
aphid
(,'ecnbuBS
(il.lSsllOpperS*
Armyworms
(".usshoppcrs
1-T/zpls.
1-1 1/2 pts.
T/2PIS.
•M.iki' full co
2 pts.
1 '/2-1 ptS.
OR
1 '/i 1 pis.
in 1 Kit.
diescl fuel
oil.*
'Apply by airc
Repeal applic
3-4 Ibs.
3-4 Ibs.
rt'Mi'.e lo h.iK
—
rafl or turbine
anons may be
movements
—
—
lun^ areas v
—
-blower spi
needed afti
o crops tak
135 ppm
8 ppm
8 ppm
Yhcn nymphs
8 ppm
ayer.
•r hatching ar
: place.
CROP
0 ""'" '
ARTICHOKES
0 BEANS
(Lima, green,
. snap, navy,
id before re(i kidn);^
wax, cowpeas.
black-eyed
peas)
0
DRY BtANS
(California &
Northwestern
U.S.)
0 LENTILS
COLE CROPS
AND LEAFY
VEGETABLES
BrornHi,
Brussels
^ sprouts,
5-corn Cabb.«sc,
Collards,
Dandelions,
Kohlrabi,
Mustard
7 greens,
.ire young Parsley,
' Turnips,
Watercress
5
d before
AMOUNT PER ACRE Interval (days)
between last
57* 25Z application
PEST EmulslfiableWettable *% Residue and harvest
Liquid Powder Dust Tolerance or grazing
Aphids
Lcafhoppers
Asparagus beetle
Thrips
Mexican bean
beetle
Leafhoppcrs
Spider mites
Japanese beetle
Aphids
Cucumber beetle
1 ygus bugs
Cowpea aphirls
Pea aphids
Aphids
Flea beetles
(cm mustard
greens only)
Caterpillars
(on cauliflower,
cnlljrds,
Brussels
sprouts and
broccoli only)
1 larlequin
cabbage IMIH
(on tollards
only)
1-2 pts.
T/2PIS.
2 pts.
1'/2-2pts.
T/2pts.
—
1-1 >/2 plS.
1>/2-2,pls. 1
Vlakc 2 or mu
2 pts.
T/2-2ptS.
1 Vi pis.
1'/2-2pts.
T/2-2pls
2 pts.
1pt.
—
—
^
5 Ibs.
e applicatio
5 Ibs.
—
—
2 Ibs.
4-5 Ibs
5 Ibs
—
—
—
25-30 Ibs.
30-35 Ibs
30-35 Ibs.
—
35 Ibs.
ns as needed
30 Ibs.
—
—
30 Ibs.
25-30 Ibs
30 Ibs.
-
NR
NR
8 ppm
8 ppm
8 ppm
8 ppm
8 ppm
8 ppm
8 ppm
8 ppm
NR
8 ppm
8 ppm
8 ppm
H ppm
10
10
1
1
1
1
1
1
1
1
—
7
3-Turnips
and
Broccoli
21 -Parsley
7
7
3-Broccoli
7
Imported <.iljli.i|;e
worm, cabbage NOIC: hir mnlrol o( rjh >.i(;r loopers. worms, and rliamondback
looper, and moths, CNTHION should be used in comhmalion with
diiimondback other recommended insecticides.
moth
-------
Table 26. (Continued)
AMOUNT PER ACRE
I-1
vo
00
CROP
PEST
57Z
Rnulsiflnble
LiouU
25Z
Wcttoble
Powder
«
Interval (days)
between last
Residue application
Tolerance t>«d harvest
Cauliflower
Celery
(Anise* and
fresh leaves
and stalks
only)
Endive
(escarole)
Lettuce
Spinach
CORN'
(Field, Sweet
and Pop)
CUCURBITS
Cucumbers
Aphids
Caterpillars
Aphids
Spider mites
Aphids
Mites
leafhoppers
Aphids
Mites
Cabbage loopcr
Aphids
Corn carworm
Aphids
Sap beetle
Thrips
Grasshoppers
Corn rootworm
adults (for
protection
of silks)
_
2 pts.
1J/zpts.
*Do not use t
T/2-2pts.
2 pts.
—
_
Slbs.
in crops grow
2 Ibs.
Slbs.
—
SO Ibs.
30 Ibs.
m for seed an
30-40 Ibs.
30 Ibs.
30-40 Ibs.
3 pts. — 30-40 Ibs.
NOTE : For control of cabbage loopers,
moths, CYTHION should be use
olher recommended i
2 pis.
Make 4-5 app
Begin trcatmc
T/2PIS.
1»/2PI5.
Make full covi
T/2PIS.
Make full covt
—
icalions al 3-
nt when 10%
—
>ragc applica
•rage applic.i
bere dry.
Sppm
8 ppm
Sppm
1
1
1
interval (days)
y8) 57Z 25i? between last
CROP PEST Bnulsifiable Wettable « Residue application
fe; Liquid Powder Dust I Toleranc*<"«! harvest
fc H or grazing
Melons
(Cantaloupes,
Casabas,
Crenshaws,
Honeydews,
Honey balls,
Muskmclons,
Persians,
Watermelons
and Hybrids
of these)
Pumpkins
Squash
EGGPLANT
GARLIC
LEEKS
SHALLOTS
MUSHROOMS
Lealhoppers
Pickleworm
Aphids
Spider miles
Cucumber
beetles
Aphids
Mites
Lcafhoppcrs
Squash vine
borers
Alfalfa loopcrs
Aphids
Spider miles
Pickleworm
Squash vine
borers
Cucumber beetles
Aphids
Spider mites
Lace bug
Thrips
Aphids
Mites
Phorid &
sciarid flics
—
—
1>/2ptS.
2pts.
'Do not apply
1'/2pts.
_
3pts.
Do not apply
—
—
—
unless plan
—
—
7lbs.
unless plan
30-35 Ibs.
20-40 Ibs.
30-35 Ibs.
30 Ibs.
Is are dry.
30-35 Ibs.
30-35 Ibs.
1 45 Ibs.
Is are dry.
For control of loopers, CYTHION
should be used in combination with
other recommended insecticides.
1>/2 pts.
2 pis.
3 pts.
Do nut apply
1pt.
3 pts.
1>/2-2ptS.
2 '/2 pts, per
130j;als.
OR
1 tbs. per
100jq, ft.
of bed
2l/2 pts. per
130 R.ils.
OR
1 tbs. pcf
100 sq. ft.
of bed
Make thornug:
Krpr.it ,ip|ilic
—
Slbs.
7lbs.
unless plan)
2lbs.
—
4 Ibs.
—
li applicatir
itions .is no
30-33 Ibs.
35 Ibs.
45 Ibs.
s are dry.
—
—
—
—
10-15 Ibs.
OR
2 Ibs. per
60ft.
sinp.le
house
n as scion as po
-------
CROP
PEST
H
VO
AMOUNT PER ACRE
57Z 25Z
Enulelfiable Wettable
Liquid Powder
Interval (days)
4* Residue application
Dust Tolerance •nd "•«»«•«
or Brazing
OKRA
ONIONS
PEAS & PEA
VINES FOR
FORAGE
PEAS
PEPPERS
POTATOES
ROOT CROPS
Beets
Carrots
Horse-
radish,
Parsnips,
Radishes,
Salsify
Rutabagas
Sweet
potatoes
Tomatoes
Aphids
Japanese beetle
Thrips
Onion maggots
Pea aphid
Pea weevil
Alfalfa loopers
Celery loopers
Aphids
Pepper maggots
Aphids
Leafhoppers
False chinch bug
Mealybugs
Aphids
Aphids
Leafhoppers
Aphids
Aphids
Leafhoppers
Morning-glory
leafminers
Spider mites
Aphids
Tomato russet
mite
Drosophila
1ft pts.
2 pts.
•Do not appl
1ft pts.
2'/2 pts;
1J/2 pts.
1>/2 -2 pts.
'Make no ap
used for ani
6 Ibs.
5 Ibs.
t after pods
4 Ibs.
6 Ibs.
—
ilication wi
nal feeds. II
be made \
20-30 Ibs.
30 Ibs.
have started t<
30-40 Ibs.
40 Ibs.
25-30 Ibs.
25-30 Ibs.
thin 7 days of
vines arc not t
within 3 days c
NR
NR
3 form.
Bppm
8 ppm
8 ppm
Bppm
larvcst if vir
o be fed app
f harvest.
•
*
3
3
*
es are to be
ication may
For control of loopers, CYTHION should be used in combination
with other recommended insecticides.
1pt.
2% pts.
Ipt.
1V4 ptS.
1Pt.
11/2-2 pts.
•If tops are to
1ft -2 pts.
2'/2 PtS.
1ft-2pts.
1J/2 pts.
1 ft-2 pts.
21/2-3 pis.
IftptS.
1pt.
—
2ft pts.
2 Ibs.
6 Ibs.
2ft Ibs.
4 Ibs.
4 Ibs.
be used as
2 Ibs.
6 Ibs.
2 Ibs.
—
2 Ibs.
—
2 Ibs.
2 Ibs.
2-4 Ibs.
6 Ibs.
—
40 Ibs.
30-35 Ibs.
25 Ibs.
30-35 Ibs.
feed.
30-35 Ibs.
40 Ibs.
30-35 Ibs.
—
25-30 Ibs.
—
35-45 Ibs.
35-45 Ibs.
35-45 Ibs.
40 Ibs.
8 ppm
Bppm
Bppm
8 ppm'
8 ppm
Bppm
Bppm
Bppm
Bppm
Bppm
NR
NR
8 ppm
Bppm
Bppm
Bppm
3
3
0
0 .
0
7*
7
7
7
3
0
0
1
1
1
1
)
E
CROP PEST
APPLES*
APPLES
(Dormant
and delayed
dormant
sprays)
APRICOTS
Wooly apple aphid
Bud moth
Green apple aphid
Rosy apple aphid
Mealybug
Codling moth
Plum curculio
Red-banded leaf
roller
Forbes scale
Putnam scale
San Jose scale
Tent caterpillars
Bagworms
Leafhoppers
Unspotted
tcntiform
leaf miner
Yellow-necked
caterpillars
Wooly apple aphid
Green apple aphid
Rosy apple aphid
Mites
Red-banded leaf
roller
Forbes scale
Putnam scale
San lose scale
Codling moth
Orange tortrix
Terrapin scale
Soft brown scale
Aphids
57Z 25Z -
nulsifiable Wettable 42
Liquid/ Powder/ tv.-..
100 gal. 100 »al.
Ipt.
1ft pts.
1ft pts.
1-2 pts.
2 pts.
1pt.
—
1-1 ft ptS.
—
—
—
—
2 Ibs.
2 Ibs.
2ft Ibs.
21/2 Ibs.
3 Ibs.
2ft Ibs.
2-2 ft Ibs.
2 ft -4 Ibs.
3 Ibs.
2 Ibs.
2 Ibs.
2 Ibs.
—
—
—
—
—
—
—
—
— •
—
—
—
Interval (days)
between last
Residue appilcatlon
Tolerance ^ harvest
Bppm
Bppm
Bppm
Bppm
8 ppm
Bppm
Bppm
8 ppm
8 ppm
8 ppm
8 ppm
8 ppm
3
3
3
3
3
3
3
3
3
3
3
3
•Consult local spray schedules for recommended combinations
of CYTHION with other insecticides for control of insect
complex on apples.
CYTHION EMULSIFIABLE LIQUID MAY CAUSE INJURY TO
MclNTOSH AND CORTLAND VARIETIES.
1 pint of 57% emulsifiable liquid phis 1 gallon of superior oil
per 100 gals, of water OR
2 Ibs. of 25% wettable powder plus 1 gallon of superior oil
per 1()0 gals, of water
MAKE FUL1 COVERAGE DORMANT OR DELAYED DORMANT
SPRAYS ONLY.
3 Ibs of 25% wettable powder plus 2 gals, superior oil per
10P ^iv of water
MAKE fULL COVLRAGL DORMANT OR DELAYED DORMANT
SPRAYS ONLY
1»/2-2nts.
4 Ibs.
—
8 ppm
7
-------
Table 20. (Continued)
O
O
HS' .' . * , ' * 'w -• • • • - .
K*i*"i-^i*.'jA' i *. j-akji^li
^ jaraura ipstt
"j '. j|
L:- ^<^ -^^^^*^J
• 57X ' 25* Interval (days,1
g Emulsifiable Wet table 4Z Residue between last
irE^-XL'^'lffliMMIfJklaSliLi.' >Ti -.V, I'A i> CROP PES'i' Liquid/ Powdur/ Dust Tolerance application
CROP
AVOCADOS
CHERRIES
CHERRIES
(Dormant
and delayed
dormant
sprays)
CITRUS
Grapefruit,
Lemons,
Limes,
Oranges,
Tangerines,
Tangelos,
Kumquats
57Z 25%
PEST Emulslflable Wcttable 4% Residue
Liquid/ Powder/ Dust Tolerance
1.00 gal. 100 eal.
Latania scale
Greenhouse thrips
Omniverous loope
Orange tortrix
Soft brown scale
Black cherry aphid
Fruit tree leaf
roller
Cherry fruit fly
Bud moth
Lesser peach tree
borer
San Jose scale
Forbes scale
IVSpts.
1%pts.
iVzpts.
1pt.
—
3 Ibs.
2 Ibs.
2 Ibs.
4 Ibs.
2-2«/2 Ibs.
—
—
—
—
8 ppm
8 ppm
Sppm
Sppm
8 ppm
Sppm
Interval (daya)l 100 eal. . 100 gal. and harvest
between last _
application Dltei
and harvest
1
FIGS
3
3
r.KAPK*
3
3
3
INJURY MAY OCCUR ON CERTAIN VARIETIES OF SWEET
CHERRIES PARTICULARLY IN THE NORTHWEST.
Aphids
Scale insects
California red
scale
Yellow scale
Purple scale
Black scale
(single & off
brooded)
Soft scale
Citricola scale
Florida red and
purple scales
(light &
medium
infestations)
Thrips
Green citrus
aphid
2 Ibs. ol 25% wettable powder plus 1 gal. superior oil per
100 gals, of water OR
3 Ibs. of 25% weltablv powder plus 2 gals, superior oil per
100 gals, of water.
MAKE FULL COVERAGE DORMANT OR DELAYED DORMANT
SPRAYS ONLY.
CONSULT L
1-1V4pls.
2pts.
iVipts./
200 gals./
acre
—
OCAL SPRAY
VOLUMES
2>/z-
3'/2 Ibs.
3-5 Ibs.
6 Ibs./
200 gals./
acre
1-2 Ibs.
1.1 IKr
SCHEDULES
OF SPRAY P
—
_»
—
FOR RECO
ER ACRE.
Sppm
Sppm
Sppm
Sppm
a nnm
MMENDED
NURSERY
7 STOCK
GRAPE
VINES
MANGO,
7 PASSION
FRUIT &
CUAVA
- (Hawaii)
7
Nltidulid
beetles
Dried fruit
beetles
Vinegar beetles
Leafhoppers
Spider mites
Mealybugs
Japanese beetle
Terrapin scale
Drosophila
(vinegar or
pomace fly)
2 qls. plus
1-2 gals.
unsuffurized
molasses
per acre
T/zpts.
iVipts.
I'/zpts.
—
I'/zpts.
NOTE: RATES
1-1 »/2 Ibs.
—
2 Ibs./
100 gals.
—
ARE PER A
THOROL
Apply
thor-
oughly to
each
cluster
50 Ibs.
20-40 Ibs.
+ sulfur
20-40 Ibs.
+ sulfur
—
—
25-35 Ibs.
CRE IN SUFFl'
GH COVERA(
Sppm
Sppm
Sppm
8ppm
8 ppm
Sppm
8 ppm
8 ppm
:iENT WAT
3E.
7
3
3
3
3
3
3
3
ER FOR
INJURY MAY OCCUR ON GRAPES OF RIBIER, ITALIA. CARDINAL
AND ALMERIA VARIETIES WHEN SPRAYS CONTAINING
CYTHION ARE APPLIED AFTER THE CLUSTERS APPEAR.
^ 'See Stored Product Section for protection of raisins.
Overwintering
grape
phylloxera
Fruit flies
For Ihe control of overwintering grape phyiluxcra on nursery
stock grape vines, remove excess soil from the roots and dip in a
solution made up of 1 io 1 Vz pinis of CYTHION 57% emulsifiable
liquid in 50 gallons of water. Submerge the entire root system in
the solution for 5 minutes. Keep ;l>e solution agitated at all times.
Fifty gallons of solution will treat approximately 500 nursery
stock grape vines. _
Add 1 Ib. parti.
hydr
For application
5 gals, of water
2 Ibs./
30-40 gal.
3 Ibs./
40-150
gal.
lly hydroltz
oly/atc to (
s to less (ha
?lus 10 tbs.
enzymatic
ed yeast prole
:YTHION sprj
n 1 acre, use 1
of partially hy(
ycasl hydrolv
Sppm
m or enzyrr
v per acre.
5 tbs. of 25°
Jrolized yea
rate.
2
atic yeast
o WP per
it protein or
-------
Table 26. (Continued)
1
> S7Z 25Z Interval (days)
Enulslflable Wottable 4Z Residue between last
CROP v PEST Liquid/ Powder/ Dust '• Tolerance application
. 100 Kal. 100 aal. < and harvoRj.
NECTARINES
PEACHES
t
PEACHES
(Dormant
and delayed
dormant
sprays)
PEARS
(cont. next pg.)
Plum curculio
Mites
Parlatoria scale
2 pts.
1-2 pts.
•Applkal
3 Ibs.
2>/2 Ibs.
2 Ibs. +
Igal.
light-
medium
oil-
ion of this niixlu
fall
—
—
re should
period.
8 ppm
8 ppm
Bppm
be made only
7
7
7
n the petal C80P
CYTHION MAY CAUSE FRUIT SPOTTING ON NECTARINES. PEARS
(continued)
European red mite
Two-spotted mile
Oriental fruit moth
Plum curculio
San lose scale
(Calif, only)
Green peach aphid
Black cherry aphid
Black peach aphid
Rusty plum aphid
Japanese beetle
lesser peach tree
boier
Terrapin scale
Cottony peach
scale
Aphids
I'iMcli Iwig
borer
Sc.ile insects
Make 2 o
2 pts.
NOTE: Pr
2|
10
ipt.
—
2 pts.
2-2 Vi Ibs.
r more applicalio
3 Ibs.
See Note
L-parc lank mix o
allons oil emuls
) gallons of wale
2 Ibs.
4 Ibs.
2-2«/2 Ibs.
ns as neet
3 pounds
on and 4
r. Apply o
—
—
Bppm
ed.
8 ppm
25% wetlable
oounds fixed cc
nly when irees
8 ppm
8 ppm
8 ppm
7
7
—
powder plus PEARS
pper per (Dormant
are dormant. and delayed
dormant
sprays)
7
PINbAPPLK
7
PLUMS &
7 PRUNES
2 Ibs. of 25% weilable powder plus 1 gal. superior oil per
100 gals, water.
3 Ibs. ol 25% weiuible powder plus 2 g.ils. superior
100 g,ils. water.
oil per
PEST
Fruil tree leaf
roller
Red-banded leaf
roller
Apple aphid
Apple grain
aphid
Forbes scale
San Jose scale
Aphids
leal rollers
IVar psylla
Scale insects
r . /r^£ir?iwjjiiv: , '^
57% 253f
Emulsiflable Wectable 42
Liquid/ Powder/ Dust
100 gal. -100 gul.
2 pis.
—
3 Ibs.
2 Ibs.
2-2'/2 Ibs.
—
—
Interval (days)
Residue between last
Tolerance application
and harvest
8 ppm
8 ppm
8 ppm
1
1
1
2 Ibs. of 25% weltanlo powder plus 1 gal. superior oil per
100 gals, water.
J Ihs. ol 25% wi'iialile powder plus J gals, superior oil per
lOOfwK. wj'er
MAKE rULL COVIRAGE DORMANT OK DELAYED DORMANT
SI'RAYS ONLY.
Mealybug
Mealy plum aphid
I'lutn curculio
Mealy plum jphid
1 esscr peach tree
borer
1 gal.
per acre
Ipt.
20 Ibs.
per acre
lib.
100 Ibs.
—
8 ppm
8 ppm
7
3
O1IIION should l>e iisi'd in Kiinhinjlinn v.uh other 0
ri-uunincmlrd mss-i In id<-s lor mniidl ol these !%su pests
~
4 Ibs.
8 pprn
3
MAKE FULL fOVEKAHE UDKMANI OR DELAYED DORMANT
SI-RAYS ONLY.
Me.ilybug
Mites
Pc.ir psylla
C'odlin); moth
I'lum curuilio
1-2 pts.
2 pts.
2-2 '/z Ibs.
3 Ibs.
—
_
8 ppm
(3 ppm
1
1
-------
Table 26. (Continued)
to
o
ro
CROP
PLUMS &
PRUNES
PLUMS &
PRUNES
(Dormant
and delayed
dormant
sprays)
QUINCES
57Z 25Z Interval (days)
Emulaifiabla Wettable 4* Residue between last
rest Liquid/ Powder/ Dust tolerance application
100 gal. 100 gal. and harvest
European red mite
Two-spotted
spider mite
Prunes: San lose
scale (Calif.
only)
Prunes: bud moth
Apply in su
—
lot.
2-3 Ibs.
mmer, repeat
See note
2 Ibs.
liter 7-10 da
—
8 ppm
f* if needed.
Sppm
NOTE: Prepare tank mix of 3 pounds 25% wettable p
2 gallons oil emulsion and 4 pounds of fixed c
100 gallons of water. Apply only when trees a
Scale insects
Aphids
Plum curculio
Codling moth
Oriental fruit moth
Forbes scale
Mites
CROP
3
BLACK-
BOYSEN-
3 BERRIES,
DEWBERRIES,
, LOGAN-
KJwderplus RASPBERRIES
re dormant. RASPBERRIES
1 pt. of 57% emulsifiable liquid plus 1 gal. superior oil per BLUEBERRIES
100 gals, of water OR
3 Ibs. of 25% wettable powder plus 2 gals, superior oil per
100 gals, of water.
2 Ibs. of 25% wettable powder plus 1 gal. superior oil per
100 gals, water.
MAKE FULL
2 pts.
Ipt.
1-2 pts.
COVERAGE DORMANT OR DELAYED DORMANT
SPRAYS ONLY.
3 Ibs.
21/2 Ibs.
2-2V2 Ibs.
—
—
—
Sppm
Sppm
Sppm
3
3
AMOUNT PER ACRE
... ,,_ Interval (dayi
_ , j,j . , _, * 4!t Residue between last
PEST ^"Jf1* H"""e »u.t Tolerance application
8nd hs>rvc«ic
Mites
Thrips
Leafhoppers
Japanese beetle
Aphids
Rose scale
Sap beetle
Cranberry fruit
worm
Cherry fruit worm
Blueberry maggot
Plum curculio
Sharp-nosed
leafhopper
Japanese beetle
3
1% pts.
1 Vi pts.
3 pts.
11/2-2 ptS.
—
—
2' Ibs.
4 Ibs.
7 Ibs.
4-5 Ibs.
2 Ibs.
4 Ibs.
—
—
40-50 Ibs.
—
—
—
Sppm
8 ppm
Sppm
Sppm
Sppm
Bppm
1
1
1
1
1
1
See Note — 25 Ibs. Sppm 0
NOTE: Blueberry maggots in the Northeast: 1 pt. of 57*/o emulsi-
fiable liquid or 2 Ibs. of 25% wettable powder plus 1 1/2 qts. of
Staley's Sauce Base # 7 in 100 gals, of water per acre and apply by
ground or air equipment. Pre-harvest interval — 8 hours.
—
1V2 PtS.
6-8 Ibs.
—
40-50 Ibs.
25 Ibs.
8 ppm
8 ppm
1
1
-------
Table 26. (Continued)
AMOUNT PER ACRE
CROP
PEST
to
O
CO
57X '
Enulsifiable
Liquid
25Z
Uectable
Powder
Interval (days)
4Z Residua between last
Dust Tolerance application
CRANBERRIES
CURRANTS
GOOSE-
BERRIES
STRAW-
BERRIES
Leafhoppers
Black-headed
fireworm
Spittlebug nymphs
Cranberry
fruilworms
iVzpts.
1>/2PIS.
2>/2 Ibs.
2i/2 Ibs.
30-50 Ibs.
—
Sppm
Sppm
3
3
DO NOT APPLY CLOSE TO OR DURING THE BLOOM OR
BERRY-SET PERIOD.
DO NOT APPLY WHEN FOLIAGE IS WET.
Mites
Japanese beetle
Currant aphid
Imported
currantworm
Aphids
Spider mites
Strawberry root
weevil
Lygus bug
Spiltlebugs
Field crickets
Thrips
Pot.ilo leafhopper
Strawberry leaf-
roller
Whilcflics
—
—
—
—
iy2pts.
1 Vz pts.
Apply to soil
lV2-3pts.
1VZ-2V4P1S.
2 Ibs.
4 Ibs.
8 Ibs.
6 Ibs.
2V2 Ibs.
4-6 Ibs.
surface befo
6 to
4-8 Ibs.
4-6 Ibs.
—
—
—
—
40 Ibs.
25-40 Ibs.
re planting an
8 inches.
25-50 Ibs.
25-40 Ibs.
8ppm
Sppm
Sppm
Sppm
Sppm
8 ppm
i work into
Sppm
8 ppm
3
3
3
3
3
3
top
3
3
CROP
PEST
57* 252
Bnulsifiable Wettable
Liquid/ Powder/
100 gal. 100 gal.
4Z
Dust
Residue
Tolerance'
Interval (daya)
between last
application
and harvest
or arazlng
ALMONDS
CHESTNUTS
FILBERTS
MACADAMIA
NUTS
PECANS
(cont. next pg.)
Aphids
Red spiders
Peach twig borer
Mites
Filbert aphid
Apple mealybug
Eye-spotted
bud moth
Scale (crawler
stage)
Tingids
Green stink
bugs
Spider mites
Aphids
1-2 pts.
1-lVipts.
No more tha
Do not appl1
1pt.
ipt.
1 Vz pts.
1-2 pts.
2-2V2 Ibs.
3-4 Ibs.
n 8 Ibs. of act
applied
2 Ibs.
' after shucks
in tr
2 Ibs.
2 Ibs.
4 Ibs.
May be appli
2-3 Ibs.
—
ual CYTHIOf
o almond tn
•>egin to oper
cated groves
50 Ibs.
—
rd during ha
—
NR
NR
•J per acre s
;es.
NR
i. Do not gri
NR
NR
NR
vest.
Sppm
0
0
tould be
ze livestock
0
0
0
0
-------
Tablr. 26. (Continued}
INJURY MAY OCCUR ON FERNS, HICKORY, VIBURNUM LANTANA, CRASSULA AND CANAERTI
JUNIPER FOLLOWING THE USE OF EMULSIF1ABLE LIQUID AND WETTA8LE POWDERS. SLIGHT
INJURY HAS ALSO BEEN REPORTED ON BOSTON, PTERIS, AND MAIDENHAIR FERNS, PETUNIAS,
SMALL-LEAF SPIREA, WHITE PINE AND MAPLES. UNDER EXTREME HEAT, DROUGHT AND DISEASE
CONDITIONS THE EMULSIFIABLE CONCENTRATES MAY CAUSE SLIGHT DAMAGE TO ELMS.
CROP
PEST
— Interval (days)
57Z 2SZ between last
Enuleiflabla Weetable AX Residue application
Liquid/ Powder/ Dust Tolerance ^^ harvest
100 gal. 100 gal._ _or grazing
PLANT
JEST
57 X Baulsifiable 25ZWettable
Liquid/100 gal. Powder /100 gal.
~~~ "~- 13
4Z
Dust
PECANS
WALNUTS
Pecan nut
rasebearer
Pecan leaf
casebearer
Pecan phylloxera
Pecan bud moth
Walnut husk fly
Aphids
Mites
—
—
—
3 Ibs.
3 Ibs.
3 Ibs.
100 Ibs.
—
10 Ibs. by
airplane
Bppm
Sppm
8ppm
0
0
0
— 8-10 Ibs.* — Sppm 0
•Per 500 gals, per acre by air-carrier type equipment.
1-1 '/2 Ibs. per 100 gals, by conventional high pressure
spray equipment.
Bait Sprays: Combine Slaley's sauce base #2 or #7 (2 qts. per
acre) to above dosages.
•Per 4
»/2-1 1
•Per 4
'/z-1 I
4-8 Ibs.*
X) gals, per ac
i. per 100 gal
sp
4-8 Ibs.*
DO gals, per ac
b. per 100 gal
sp
40-60 Ibs.
re by air-carri
i. by convent
ray equipmen
re by air-carri
5. by convent
ay equipmen
Sppm
cr type equip
onal high pr
t.
Sppm
cr type equip
onal high pr
t.
0
iment.
essure
0
mcnt.
essure
ORNAMENTALS
(Sec directions
for mixing small
quantities, pg.3)
Oyster shell scale
Lace bug
Euonymus scale
Aphids
Mealybugs
Spider mites
Whitefly
Four-lined leaf bug
Japanese beetle adult
Potato leafhopper
Tarnished plant bug
Thrips
Rose leafhopper
European pine
shoot moth
Scurfy scale
1pt
Apply when scale
1pt.
1-11/zpts.
1J/2pts.
I'/apts.
iVipts.
T/zpts.
iVzpts.
crawlers have sett
4lbs.
—
2 1/2 Ibs.
2>/2 Ibs.
2«/z Ibs,
2'/2 Ibs.
—
ed on foliage.
—
—
See Note
—
See Note
—
—
NOTE: Apply sufficient amount for good coverage.
Birch leaf miner
Boxwood leaf miner
Bagworms
Tent caterpillar
Azalea scale
Oak kernes'
Pine leaf scale
Magnolia scale
2pts.
2pts.
2pts.
2pts.
—
4 Ibs.
2 Ibs.
—
—
See Note
—
—
'Apply when scale crawlers have settled on foliage.
-------
Table 26. (Continued)
L
j
- ZZT.^r.^MtaOtfc&'L
„..„-
FLANT
NJ
O
Oi
Dust
ORNAMENTALS
(See directions
for mixing small
quantities, pg. 3)
GREENHOUSE
(in and around
greenhouses
and gardens)
ROSES,
CHRYSAN-
THEMUMS,
CARNATIONS
Fletcher scale*
Florida red scale*
Juniper scale*
Black scale crawlers
Monterey pine scale
Soft scale
Pine needle scale
Wax scale
2 pts.
2 pts.
3 Ibs.
6 Ibs.
—
—
•Apply when scale crawlers have settled on foliage.
2'/4 pts.
2»/2 pts.
4 pts.
6 Ibs.
6 Ibs.
4 Ibs.
—
—
—
2 qts. Apply in spring when crawlers are active.
Repeat 1 or 2 full coverage applications at
10 day intervals.
NOTE: Apply sufficient amount for good coverage.
Millipedes
Springtails
Sowbugs
Aphids
Whiteflies
Mealybugs
Thrips
Two-spoiled mite
Mix 1 teaspoonful of 57% E.L. in 1 gal. of water and
apply to 150 square feet of soil surface or where
insects congregate
OR
apply dust at the rate of 1 Ib. per 150 square feet of
soil surface or where insects congregate.
Repeat at 7-10 day intervals as needed.
Apply one pound c
f 15% aerosol per 5
0,000 cubic feet.
PRECAUTIONS FOR USE OF CYTHION ON LIVESTOCK:
DO NOT TREAT ANIMALS UNDER ONE MONTH OF ACE.
WHEN APPLYING SPRAYS AND DUSTS, AVOID CONTAMINATION OF FEED,
FOOD CONTAINERS AND WATERING TROUGHS.
DO NOT APPLY TO LACTATING DAIRY ANIMALS OR NON-LACTATING DAIRY
ANIMALS WITHIN TWO WEEKS OF FRESHENING UNLESS OTHERWISE NOTED.
RESIDUE TOLERANCE: 4 ppm in or on meat and meat by-products (Uses on dairy cattle subject to
pending petition.)
AMOUNT
EI_._7
CATTLE
(Beef &
Non-milking)
HORSES
PEST 57.Z Emulaifiable Liquid 252 Uettable Powder 4Z Dust
Lice
Ticks
Horn fly
•Apply c
1 gal. per 100 gals.
OR
6'/2 ozs. per 5 gals.*
•Treat aninru
1-2 gals, per 100 gals.
OR
6l/j-13 ozs. per 5 gals.*
•Treat anirric
Repeat applications at 2 v
1-1 Vi gals, per 100 gals.
OR
6Vz-10 ozs. per 5 gals.
n back and neck of the anin
day int
16 Ibs. per 100 gals.
OR
Vt Ib. per 5 gals.*
Is thoroughly.
16-32 Ibs. per 100 gals.
OR
%-1'/2 Ibs. per 5 gals.*
ils thoroughly.
veek intervals if needed.
16-24 Ibs. per 100 gals.
OR
%-l»/4 Ibs. per 5 gals.
tals and repeat applications
ervals.
*
•
4 tbs. per
animal*
at 10-14
BACK RUBBING DEVICES: For the reduction of lice, apply a mixture of 2% CYTHION
(using CYTHION 57% emulsifiable liquid) in fuel oil.
There may also be a reduction in horn flies. These dev ices
should be made continuously accessible one to each
35-45 head of cattle and re-treated every 2-3 weeks.
DO NOT MAKE ACCESSIBLE TO LACTATING DAIRY
ANIMALS OR NON-LACTATING DAIRY ANIMALS WITH-
IN 2 WEEKS OF FRESHENING.
-------
Table 26, (Continued)
PRECAUTIONS FOR USE OF CYTHION ON POULTRY:
AVOID CONTAMINATION OF FEED AND FEEDING- TROUGHS AND
WATER FOUNTAINS WITH SPRAYS OR DUST.
WHEN USING EMULSIFIABLE LIQUID AND POWDER, USE A HIGH PRESSURE SPRAYER
FOR SURFACE SPRAYS.
RESIDUE TOLERANCE: POULTRY—4 ppm in or on meat and meat by-products EGGS—0 ppm
A M 0 U
Horn fly
37» Knulsitiable Liquid 251 Wettable Powder 4* Dujt
4 tbs. per
i i i animal
Apply on back and neck of the animals and repeat applications at 10-14
day intervals.
DO NOT APPLY TO DAIRY CATTLE LATER THAN 5 HOURS BEFORE MILKING OR
DURING MILKING.
DO NOT SPRAY OR DIP DAIRY ANIMALS IN CYTHION.
RESIDUE TOLERANCE: 0 ppm in milk.
HOGS
Lice
Sarcoptic
mange
1 gal. per 100 gals.
OR
6V4 ozs. per 5 gals."
'Treat animals, pens, anc
1 gal. per 100 gals.
OR
6'/2 ozs. per 5 gals.
16lbs. per 100 gals.
OR
% Ib. per 5 gals.*
litter thoroughly.
16 Ibs. per 100 gals.
OR
% Ib. per 5 gals.
•
—
Use extreme care lo cover all body surfaces including the inside of the ears.
Second treatment may be necessary in 10 days.
HOGS SHOULD BE KEPT OUT OF SUN AND WIND FOR A FEW HOURS
AFTER TREATMENT.
SHEEP &
COATS
Lice
Ticks
Keds
1 gal. per 100 gals.
OR
6'/z ozs. per 5 gals.*
•Treat animals thoroughl
Repeat applicatioaafter ;
16 Ibs. per 100 gals.
OR
% Ib. per 5 gals.*
y.
. or 3 weeks if needed.
DO NOT APPLY TO MILK GOATS.
—
Ettii r ' •
CHICKENS,
DUCKS, GEESE
AND TURKEYS
Direct
application
Tail-dipping
Roost paint
Premise
treatments
(cont. next pg.)
PEST 57X Emulaifiabla Llauid 25% Wettable Powder 4Z Dust
Northern fowl
mite
Poultry lice
Chicken red
mite*
•As a supplem
Northern fowl
mite
Chicken body
lice
Shaft lice
Chicken red mite
Poultry lice
Northern fowl
mite
Chicken red mite
Poultry lice
Flies
2 tbs. per 1 gal.
water per 100-1 50
birds.
Repeat application in
necessa
ent to premise treatmc
SVz ozs. per 15
gals, water per 400
birds.
Hold bird by wings
and dip 3 to 4
inches of tail into
solution. Treat
vent and surround-
ing areas.
Repeat in 7-10 days i!
2-7 ozs. per 1 gal.
water.
Brush on at rate of 1 p
4 tbs. per 1 gal.
water.
Apply liberally to litte
roost nests and adjace
into cracks a
2Vz oz. perl gal.
water per 100-150
birds.
4-8 weeks or when
ry.
nt for chicken red m
necessary.
t. per 150 ft. of roost.
5 oz. per 1 gal.
water.
r, walls, ceilings,
it areas. Force spray
nd crevices.
Dust individual
birds with a shaker
can or rotary hand
duster.
ite.
—
(Northern fowl
mite. Chicken red
mite. Poultry lice)
1 Ib. per 50-60 sq.
ft. of litter and
floor space and to
nests, roosts, and
adjacent areas.
Apply with a
rotary hand duster,
puff duster or by
sprinkling from
can or other
container.
-------
Table 26, (Continued)
DO NOT APPLY DIRECTLY TO DOCS AND CATS UNDER ONE MONTH OF ACE.
^naam-^--- ....... ..J PEST 57.X Etnulsifloble Liquid I25X Wettable Powder AX Dust
IM, „....,.. ,,,.j
Premise
treatments
Range
treatments
Dust bath
boxes
Dust bath
boxes,
Natural
soil
wallows
Range pens
Bioodcr
house
DOCS & CATS Fleas
1 0
V
T -•- •••".• '--- — m R
PEST 51% Enulslf iable Liquid 25Z Wettable Powder AX Duet PET QUARTERS, Fleas 5 o
Poultry ticks
Chiggers
Treat range th
Repeat every .
Northern fowl
mite
Poultry lice
Stick tight flea
Stick tight flea
Repeat in 28 d
Stick tight flea
on brooder
house chicks
Distribute the
6-7 ozs. per 1 gal.
water.
Apply liberally to
walls, ceilings
and adjacent areas.
Force spray into
cracks and
crevices.
Vz pt. per acre
oroughly day before pla
2-3 weeks.
—
™"
ays and then as often as
dust evenly in each cor
cing poultry on range.
—
"
necessary.
tier of the brooder hou
— LAWNS sq.
R
R
25 Ibs. per acre.
1 Ib. dust per box
(18" x 12" x 3")
per 30 hens.
Remove boxes
when dust has
been used.
15 Ibs. per box
(2"x3'xT)
per 100 birds
OR
Apply in natural
soil wallows at the
rate of 7l/z Ibs.
per 50 birds.
1 Ib. per 20 sq. ft.
of surface.
2 Ibs. per 100
chicks.
se.
z. per gal. water — Make complete
coverage
Vet the animals throughly using a hand sprayer.
epeat treatments may be used within 2 to 3 weeks.
z. per gal. water
•1 gal. per 1,000 1-2 Ibs. per 1,000
ft. of surface. *<*• ft- of surface.
emove manure or debris before treating.
epeat treatment within 3 to 4 weeks if necessary.
-------
Table 26. (Continued)
O
00
HEAD AND BODY LICE ON HUMANS
Apply by means of a hand or power duster, CYTHION 1% dust to head, cap,
sleeves, the back through the neck opening along the seams of clothing thor-
oughly and to Ihe crotch from front to rear. Pat clothing thoroughly over the
body to assure maximum distribution of the dust.
One ounce of CYTHION 1% dust is sufficient to thoroughly treat an adult
fully clothed. Sprinkle excess dust over bed clothing, blankets and other pos-
sible louse habitats. Repent at 2 week intervals until infestation is eliminated.
HOMES, DAIRIES, FOOD PROCESSING PLANTS
CAUTION: CYTHION SPRAYS MAY DAMAGE FINISHED SURFACES
AND KAIIKICS. AVOID CONTAMINATION OK FOOD. UTKN8II.S. MILK.
MII.K EQUIPMENT, AND WATER. DO NOT USK IN MILK PROCESSING
ROOMS.
ANTS, CRICKETS, CLOVER MITES, EARWIGS, PANTRY PESTS*, SCOR-
PIONS, SILVERPISH, SPIDERS
In and about hnmus, dairius and food processing plants, us«; CYTHION 3% in
either wuter or dr.odomcd.kerosene, or CYTHION 3% pressurized spray.
To make water solution — dilute 3 tablespoonfuls of CYTHION 57% emulsifi-
able liquid in 1 quart of walcr, or 6Vi ounces per gallon.
To make oil solution - dilute 1 part of CYTHION 57% emulsifiable liquid
in 19 parts of a mixture ccmsisling of 4 parts kerosene type solvent and 1 part
aromatic hydrocarbon type solvent.
Apply by means of a coarse spray, paint brush, or pressurized spray to win-
dow sills, baseboards, drainboards, under sinks, stoves, cracks, crevices, and
to other ureas frequented by insects.
Apply CYTHION 4% dust liberally to window sills, cracks and crevices,
around doors, baseboards, storage areas, bookcases, under sinks and to other
areas frequented by these pests.
CENTIPEDES, SCORPIONS
Apply CYTHION 4% dust liberally to window sills, cracks and crevices,
around doors, baseboards, storage areas, bookcases, under sinks and to other
areas frequented by these; pests.
FLEAS, BROWN DOG TICKS
Apply CYTHION 4% dust liberally to floors, cracks and crevices, sleeping
quarters of animals, and to other arras frequented by these pests.
FLEAS, LICE, TICKS, AND OTODECT1C MANGE ON DOGS AND CATS
Fleas, Lice, and Ticks: Apply CYTHION 5% pressurized spray for 25 to 30
seconds per 18 to 20 pound dog, and for 15 seconds per 5 to 8 pound cat. Spray
from tail to neck, legs, and under body. Repeat treatment in 7 days, if neces-
sary. Wash hands after pressurized spray applications.
Olodcctic Mange (Ear mite): Cleanse infested ears and apply CYTHION 5%
pressurized spray to ears only. Repeal treatment in 7 days if necessary. Wash
hands after pressurized spray applications.
BEDBUGS
Use CYTHION 57% emulsifiahle liquid at Ihe rule of 2 to 4 lablespoonfuls per
gallon of iluodori/.ed kcriitiune.
Apply lightly to all mattress surfaces in sufficient qtiiinlily to "mist" the fabric
and generously to buds and woodwork, with special care taken to wot jll pos-
sible hiding places.
CARPET BEETLES, CLOTHES MOTHS
Use a CYTHION 3%water or oil-based spray or CYTHION 3% pressurized
spray.
Apply to baseboards, floors (including areas under carpets, along margins of
carpels and in closets), behind radiators and other lint accumulation areas,
closet shelves and walls, and infuslud surface areas of carpeting.
Application of 3% oil or water spray or low pressure spray to the areas men-
tioned above will also control clothes inolh larvae in these locations.
If clothing or woolen goods are to be protected from clothes moth attack, they
should receive regular treatments with a suitable mothproofing material.
ROACHES
In and about homes, dairies and food processing plants, use CYTHION 3%
in either water or deodorized kerosene, or CYTHION 3% pressurized spray.
To mnke water solution - dilute 3 tablespoonfuls of CYTHION 57% emulsi-
fiable liquid in 1 quart of water (BVa ounces per gallon).
To make oil solution - dilute 1 part of CYTHION 57% emulsifiable liquid in
19 parts of a mixture consisting of 4 parts kerosene type solvent and 1 part
aromatic hydrocarbon type solvent.
•Pantry pesls tui.h as the exposed singes ol: saw-l»olhed grain beetle, (lour bccllc, rice
weevil, cigarette buelle, drug More bcclla. and Indian meal moth.
-------
Table 26. (Continued)
to
O
VO
Apply by means of a coarse spray, paint brush, or low pressure spray to win-
dow sills, baseboards, drainboards, under sinks, stoves and to other areas
frequented by insects.
Apply CYTHION 4% dust liberally to window sills, cracks and crevices,
around doors, baseboards, storage areas, bookcases, under sinks and to other
areas frequented by these pests. Spray surfaces until wet. Repeat applications
as necessary. Care should be taken to thoroughly treat all cracks and crevices.
Use a CYTHION 1%, 2% or 4% aerosol containing a knockdown agent.
• AVOID PROLONGED OR REPEATED 'CONTACT WITH SKIN WHEN
USING AEROSOLS.
• WASH THOROUGHLY AFTER USING AEROSOLS.
• KEEP OUT OK REACH OF CHILDREN.
• REMOVE FISH FROM ROOM DEFORE APPLYING AEROSOLS.
• AVOID APPLYING DIRECTLY TO ORNAMENTAL PLANTS IN THE HOME.
ANT MOUNDS
Use Wi pts. of CYTHION 57% emulsifiable liquid or 3 Ibs. of 25% wettable
powder in 100 gallons of water. •—
t
Spray ant hills thoroughly so that they are well soaked. For other small ants
in flower beds, lawns, around trees, spray lightly in the infested areas.
Repeat in 10-15 days if ants return.
LAWNS
For the control of ground pearls in lawns, apply CYTHION 57% emulsifiable
liquid at the rate of 3 to 4 quarts or 10 pounds of CYTHION 25% wcltable
powder pur acre in 100 gallons of water.
Make full covqrage application to soil surface when ground pearl nymphs arc
in (he pink, "crawlnr" or active stage and immediately wash into soil with
additional water.
MOSQUITOES AND SMALL FLYING INSECTS
NOTE: CYTHION 57% EMULSIFIABLE LIQUID MAY CAUSE SPOTTING
ON AUTOMOBILE PAINT FINISH. CARS SHOULD NOT BE SPRAYED
DIRECTLY. IF ACCIDENTAL EXPOSURE OCCURS. THE CAR SHOULD
BE WASHED IMMEDIATELY.
OUTDOORS: Use a CYTHION 2% to 5% area spray, fog or aerosol. As a 2%
area or patio spray, dilute 57% emulsifiable liquid 1 part to 28 parts water.
When using kerosene type solvents, such as fuel oil or diesel oil, as carriers,
dilute 1 part 57% emulsifiable liquid in 20 parts of a mixture consisting of 4
parts kerosene type solvent nnd 1 part aromatic hydrocarbon type solvent.
For 5%, dilute 1-11 using similar solvents. Repent applications as necessary.
Avoid applying oil-based formulations to plants as injury may occur.
CYTIMON may be toxic to r.ertuhi species of fish, particularly in shallow
water.
Apply CYTHION 4% dust liberally around duors, winduwj and porches and
to other flat surfaces where pests are known to alight or congregate.
MOSQUITO LARVAE IN STANDING WATER: Apply CYTHION 57°o emul-
sifiable liquid at the rate of III fluid ounces (approximately Vi pound of actual
CYTHION) per acre. Mix in sufficient water or oil to obtain even coverage
when applied by air or ground equipment.
INDOORS: Use a CYTHION 2% liquid space and contact spray or a CYTHION
pressurized spray or aerosol containing a knockdown agent.
Rooms should be thoroughly misled to envelop insects present and should bn
kepi closed for 5 lo 10 minutes. Sweep up and destroy fallen insects. Repeat
applications as necessary.
DO NOT CONTAMINATE FOOD. UTENSILS, MILK. MILK EQUIPMENT
AND WATER.
AVOID PROLONGED OR REPEATED CONTACT WITH SKIN WHEN
USING AEROSOLS.
WASH THOROUGHLY AFTER USING AEROSOLS.
KEEP AWAY FROM HEAT. SPARKS AND OPEN FLAMES
KEEP OUT OF REACH OF CHILDREN.
REMOVE FISH FROM ROOM lir.HMi: APPLYING AFROSOLS
AVOID APPLYING DIRECTLY IX) ORNAMENTAL PLANTS IN THE 1IOME.
FLIES
For use in and iiround buildups wliii.h house domestic. anii:iais. .insund yards
and meal pror.i-ssms plants. Do not use when plai.'. is in oper.sti"-i. Cm'er all
equipment and j>ru::i-ssine, surfai.es or wash lluiruiinhly before use.
-------
Table 26. (Continued)
NJ
H
O
STRAIGHT CYTIIION SPRAYS
Amount
Spray
Ignl.
2V, Rn)s.
12 HS.
100 gals.
Amount Amount
Emulsltioble OR 25«/t Wettoble
Liquid Powder
Stbs.
1 cup
lf]l.
2 gills.
lib.
Slbs.
40 lb«.
BAIT SPRAYS (WITH SUGAR)
Add
Corn Syrup
7tbs.
1 cup
ZVi lb».
20 Ibs.
•Use unsiilfunzec
7tba.
1 cup
iqt.
2 gals.
molasses.
Apply as a spray at the rate of 1 gallon per 1,000 square feet on pointed sur-
faces and 2 gallons per 1,000 square feet on unpainled surfaces where flics
alight or congregate, such as walls, ceilings, stanchions, windows in dairy
barns, fences, around garbage cans, etc.
As a floor treatment bait spray, use 5 ounces of CYTHION 57% emulsifiable
liquid with 1 cup corn syrup or sugar in 2 gallons of water. As a spot treatment
this mixture can also be applied to windows, stanchions, support beams,
doors, etc. For control of fly maggots, apply as a bail spray over the surface of
manure or poultry droppings. In loafing sheds, spray the dry bedding within
18 inches of the walls and around upright braces. For effective control in and
around dairy barns and nlhcr agricultural premises, fly-breeding sites such as
manure and other waste materials should be eliminated. Do not apply to
freshly whitewashed surfaces. Wait 14 days before applying. Repeat appli-
cations as necessary.
• AVOID CONTAMINATION OF MILK. MILK EQUIPMENT AND WATER.
• AVOID CONTAMINATION OF FEED AND FOOD PRODUCTS, ALSO
DRINKING FOUNTAINS AND FEED TROUGHS.
• REMOVE I.ACTAT1NG DAIRY ANIMALS FROM BUILDINGS BEFORE
TREATING. ALSO REMOVE ANIMALS UNDER ONE MONTH OF AGE
BEFORE TREATING.
DRY MILK PROCESSING PLANTS
• For the prevention of spread and the reduction of infestation of black carpet
beetles and Trogodrrmu species, in plains processing dry milk.
« Mix 1-pi. of CYTIIION 57% emulsifiable liquid or IVi Ibs. of CYTHION 25%
wettable powder in 2Vi gals, of water.
• Clean premises thoioughly before applying and maintain good sanitation at
all times.
• Use spray equipment and nu/ylc:> that will produce a coarse spray.
• Application must be made only by an experienced or trained person.
• Apply as a residua! spray In all sections of the plan! and warehouses where
insects hide or crawl such as cracks,corners, ndjji-s of flours, lower parts of
walls, floors undrr slor,ij;i' platforms and umlrrm.-ulh and behind protected
places.
• Avoid contamination of milk, dry milk, equipment, utensils, work surfaces,
containers and liners.
• Repeat application as necessary.
STORED GRAINS AND PEANUTS
GRAINS
For the protection of stored grains, such as wheat, oats, rice, corn, rye, barley,
grain sorghum, and field or jiarden scuds, against confused flour beetle, rice
wcovil, granary weevil, snw-tuothed grain beetle, flat grain beetle, red flour
beetle, ru.'ily grain beetle, Ic-sscr gr.iin hnn.T, Indian meal moth, and for con-
trol of cereal leaf beetles, apply CYTIIION 57% emulsifiable liquid as follows:
RESIDUAL SPRAY -- BEFORE STORING CHAINS: For a residual wall, floor.
and machinery spray.in grain elevators, in treating truck beds, box cars, and
ships' holds before loading grain, apply 1 gallon of CYTHION 57% emulsifi-
able liquid per 25 gallons of water making thorough application. Before apply-
ing spray, clean elevators, box cars. etc. thoroughly. Remove and burn all
sweepings and debris.
GRAINS GOING INTO STORAGE: Apply 1 pint of CYTHION 57% emulsi-
fiable liquid in 2-5 gallons of water per 10UO bushels. Apply as the grain is
being loaded or turned into final storage.
AFTER GRAINS ARE STORED: To protect stored grains from attack by
Indian meal moth, apply CYTIIION 57% emulsifiable liquid to the surface of
clean or uninfesled grain at the rate of 'A pint in 1-2 gallons of water per 1000
square feel of grain surface area. Apply Ihe spray evenly over the surface of
tin; grain. Apply immediately aflor grain i.s loaded into storage and repeat if
necessary.
RKSIUUAL SPRAY — BOX CARS FOR LOADING AND TRANSPORTING
BAGGKD FLOUR AND PACKAGED CEREALS: For the control of confused
flour beetle, rice weevil, granary weevil, saw-toothed grain beetle, f!4t grain
bcielle. red flour beclli;. rusty grain beetle, lesser grain borer, Indian meal moth
and mite pests infcslini; empty box cars into which bagged flour and packaged
cereals are to be loaded and transported, apply CYTHION ~<~"a emulsifiable
liquid as follows:
1. Clean the box cars thoroughly, then remove and burn all sweepings and
debris.
2. Spray walls and floor to Ihe point of run-off with cither 1 gallon of
CYTHION 57"o emulsifiahlr liquid in 25 gallons (if wali-r, or one gallon of
CYTIIION 57% cinulsifi iblr liquid in 19 gallons of dcoduri/.cd U-rosene. (The
drmlori/od kiTii.seni- !,«lulinn should In- mad<' up of 4 p.ir'.s kiTtoi-m1 Up-
solvent plus one par! aromatic hydrocarbon type solvent.)
3. Let the sprayed box car stand empty with Ihe doors open until the spray
has thoroughly dried.
-------
Table 26. (Continued)
to
H1
H
4. Line the walls and floors of the box car with kraft paper before loading.
FIELD AND GARDEN SEEDS: Field and garden seeds can be protected
Bffainst the above grain pests with a dosage of V> pint of CYTHION 07%
cmiilsifjable liquid in l-2Vi gallons of water per 500 bushels of seed.
CYTHION may be used under the requirements of the Khapra beetle quaran-
tine, where water or diescl oil emulsions are indicated, as prescribed by the
current quarantine instructions.
PEANUTS
For the control of stored peanuts against infestations of red flour beetle,
Indian meal moth, confused flour beetle, rice wuevil, flnt grain beetle, rusty
grain beetle, lesser grain borer, granary weevil uud saw-toothed grain beetle,
apply CYTH1ON 25% wetlable powder as follows:
RESIDUAL WARKHOUSE SPRAY - BEFORE STORING PEANUTS Clean
warehouse thoroughly of trash and remains of old-peanuts 1-2 weeks before
new peanut crop is stored. Then, thoroughly spray the interior of the empty
warehouse, especially cracks and protected places. Treat outside walls to a
height of C-8 feet and the ground to a distance of 6 feet from the warehouse.
Use 1 pint of CYTHION 57%' cmulsifiable liquid in sufficient water to make
2V> gallons of spray or, 1 gallon with 19 gallons of water. Apply as a coarse
spray at the rale of 2 gallons per 1000 square feet of surface or to run-off.
BULK SPRAY TREATMENT-PEANUTS GOING INTO STORAGE: Use
CYTHION !i7% emulsifiable liquid at the rate of 2Vi pints in 5 gallons of water
for each 15 tons of farmers' stuck peanuts as they go into storage.
Use good spray equipment. Apply coarse spray uniformly. Preferably, use a
suitable mechanical spray applicator that regulates the rule of application to
the flow of peanuts. Adjust the operating pressure of spray pump and size of
nozzle opening to correlate the amount ol spray delivery with the rale of flow
of peanuts being treated. Avoid spraying with a fine mist that drifts away,
by using low nozzle pressure. Shield the nuzzle against wind and air currents.
AFTER PEANUTS HAVE IIEEN HULK TKEATKU. USE CYTHION 257o
WETTAULK POWDER AS A SUPPLEMENTAL SURFACE SPRAY AS FOL-
LOWS:
Use 1 V« pounds ol CYTHION 25% wellable powder in 2 gallons of water for
each 1UUO square feet of surface.
Apply the first surface treatment as soon as the bin is filled and leveled, but
not later than the first week in October. Apply the second surface treatment
one month later, followed by subsequent treatments at 2-month intervals.
For applying the wettablc powder surface- treatments, use a piston-pump type
power sprayer, equipped with an agitator, and with a nozzle capable of deliv-
ering a coarse spray. Use spray equipment with sufficient capacity and power
to cover large surfaces thoroughly.
STORED PRODUCTS
BAGGED CITRUS PUI.P
RESIDUAL WARKHOUSE SPRAY- BEFORE STORING: Before ba;:ged cit-
rus pulp is stored, thoroughly clean warehouses by removing and burning nil
debris and sweepings. Thoroughly spray with sufficient pressure the interior
of empty warehouse (including cracks and protected ]>].\;:es;). outside walls to
height of (i-fi feet, and the ground to a distance, of about U f;:el from wart-house,
by diluting 1 pint of CYTHION 57% emulsifiahle liquid in sufficient water to
make 2V> gallons of spray ur, 1 gallon with 1!) gallons of water.
Apply finished spray at the rate of 2 gallons per 1000 square feet of
surface or to run-off.
GOING INTO STORAGE: For the protection of bagged citrus pulp in storage
against the cigarette beetle, saw-toothed grain beetle, confused flour beetle,
red flour beetle, flat grain beetle, Indian meal moth, An^oumois gr.iin moth.
Mediterranean flour moth and the almond moth, use 12 ounces of CYTHION
25% wellablc powder per gallon of water and apply at the. r.ile tif two gallons
per 1000 square feel of exposed b.ig surface area when hugged citrus pulp is
slured. Make two separate spray applications initially when bascn! citrus
pulp is stored. Once each month thereafter throughout sloray period use h
ounces per gallon of water and apply at the rate of two gallons per 1000 square
feel of exposed bag surface area.
Do not use treated burlap bags other than for dried citrus pulp
CATTLE FEED CONCENTRATE BLOCKS
For the protection of nonmedie.atc'd cattle feed concentrate blocks in storage
against cigarette beetles, usu paper treated with CVT1I1ON f>7"a cmulsifiable
liquid at the rate of 10U nig. per square foot on the side next to the feed con-
centrate.
Use 4 fluid ounces of CYTHION .17% emulsifiable liquid j»>r quart of water
and apply to approximately 710 square feel of paper surface.
-------
Table 26. (Continued)
DROSOPHILA FLIES &
DRIED FRUIT BEETLES
on and around Cull Fruit
and Vegetable Dumps
DROSOPHILA FLIES
in and around Wineries
and Processing Plants
DROSOPHILA FLIES &
DRIED FRUIT BEETLES
on and around Cull Fruit
and Vegetable Dumps
CYTHION 57% Emulsifiable Liquid
For control of Drosophila flies and dried fruit beetles on and around cull
fruit and vegetable dumps, mix 1 Vt gallons of CYTHION 57% emulsifiable
liquid in 100 gallons of water and apply as a drench using 8-10 gallons of
spray per 100 square feet.
For best results, dumps should not be over 18 inches deep.
DO NOT FEED TREATED FRUIT AND VEGETABLES.
CYTHION 57% Emulsifiable Liquid
For control of Drosophila flies in and around wineries and processing
plants, paint all doors and window screens with a solution containing 3Vz
ounces of CYTHION 57% emulsifiable liquid in 1 quart of water.
AVOID CONTAMINATION OF WINE, FOOD, UTENSILS, EQUIPMENT
AND WATER.
CYTHION 25% Wettable Powder
'•ot control of Drosophila flies and dried fruit beetles on and around cull
tuit and vegetable dumps, mix 32 pounds of CYTHION 25% wettable
5owdur in 100 gallons of water and apply as a drench using 8-10 gallons
of the spray per 100 square feet.
•or best results, dumps should not be over 18 inches deep.
DO NOT FEED TREATED FRUIT AND VEGETABLES.
One treatment should give satisfactory protection of blocks against cigarette
beetles for 3 months or one storage season.
Before nonmedicated cattle feed concentrate blocks are stored, thoroughly
clean storage areas by removing and burning all debris and sweepings, then
apply as a residual spray, 1 gallon of CYTHION 57% emulsifiable liquid per
25 gallons of water making thorough application.
RAISINS
For the protection of grapes (raisins) against the raisin moth, dried fruit beetle
and vinegar fly during drying in the field, and for protection against the Indian
meal moth and saw-toothed grain bcclle during storage, apply V<-lVi ounces
of CYTHION 57% emulsifiable liquid per 144 square f«et of paper used as
drying trays (100-200 mg. actual CYTHION per square foot).
Raisins should be screened to remove dead insects and any other debris before
storing.
Such treatment will protect raisins in storage for six months.
-------
This information is presented in the form of the manufacturer's
tables because it would be difficult, if not impossible, to improve
on the quality of presentation of the registration data and use direc-
tions as set forth therein.
Since these tables were prepared, a number of uses of malathion pre-
viously registered on a "no residue - no tolerance" (NR) basis have been
covered by finite tolerances. All tolerances established for malathion
up to and including April 1974 have been included in Table 9, p. 57.
The malathion formulation ultra-low volume (ULV) concentrate,
containing 95% of active ingredient (AI), equivalent to 9.7 Ib Al/gal is
intended for use, undiluted, in specially designed air or ground equipment
capable of applying ULV of spray for use on the crops against various
insects. (See Table 28.)
Due to its physical, chemical, and toxicological properties, mala-
thion is well suited for the ULV method of application. It is estimated
that the malathion ULV concentrate leads all other formulations in the
total quantity of active ingredient applied in this form.
The registration data on malathion summarized in Tables 26 through
28 show that malathion is one of the most versatile insecticides avail-
able today. It is registered and recommended for use on a large number
of agricultural, horticultural, ornamental and other crops; for the
control of insect and mite pests affecting man and animals (including
important disease vectors and other insects of public health importance);
and for stored products. Thus, malathion is widely used not only in
agriculture, but also by commercial, industrial and institutional organi-
zations; in the home and garden field; and in insect abatement, quarantine
and other control programs carried out by governmental agencies.
State Regulations - Malathion is one of the least toxic synthetic insecti-
cides, rated only "slightly toxic" to humans and most other nontarget
species. It is rapidly degraded after application. Due to these favor-
able properties, malathion is not currently subject to specific use
restrictions under state pesticide laws or regulations.
Production and Domestic Supply of Malathion in the United States
Volume of Production - According to the United States Tariff Commission
final report on synthetic organic chemicals,— there has been only one
basic producer of malathion in the United States up to and including
1972, American Cyanamid Company.
if U.S. Tariff Commission, Synthetic Organic Chemicals, U.S. Production
and Sales. 1972, TC Publication 681 (1973).
213
-------
Table 27. REGISTERED USES OF MALATHIUN ULV CONCENTRATE
(Crops and Other Uses, Pests, Dosage Rates
and Use Limitations)—'
Btluii uiing. rtid Iha Uiiatnuni Int the piopei
methods tnd procedure! which mull be
followed to ichnvi effective mitcl control ind
avoid permtnent damage to auiomobili and
other paint Imiihii.
THIS PRODUCT IS HIGHLY TOXIC
TO BEES EXPOSED TO DIRECT
TREATMENT. PROTECTIVE INFOR-
MATION MAY BE OBTAINED FROM
YOUR COOPERATIVE AGRICULTUR-
AL EXTENSION SERVICE.
DISCLAIMER
American Cyanamid Company does not assume
any responsibility for any damages which result
from fiilun to properly disign. maintain or
operate any ULV equipment or from failure to
determine or to obtain proper droplet site.
American Cyanamid Company warrants only
that the material contained herein conforms to
the chemical description on the label and is
reasonably fit for the use therein described
when used in accordance with the directions for
use.
Any damages arising from a breach of this
warranty shall be limited to direct damages, and
shall not include consequential commercial
damages such as loss of profits or values, etc.
American Cyanamid Company makes no other
express or implied warranty, including any
other express or implied warranty of FITNESS
or of MERCHANTABILITY.
BUYER assumes the risk of any use contrary to
label instructions, or unBtr abnormal con-
ditions, or under conditions not reasonably
foresanblg by American Cyanamid Company.
AGRICULTURAL USES
Active Ingredient:
Malathion**
Inert Ingredients
**0,0-dimethyl phosphorodithioate of diej
(One gallon contains 9 J-poo
DIRECTIONS FOR USE
Do not use this product for any us*s other than
those specified herein.
MALATHION is used undiluted in specially
designed aircraft or ground equipment capable
of applying ultra low volumes for control of the
insects indicated below. Aerial applications are
most effective when made at a boom height of S leet and a swath
width of SO feet. Do not make application whan winds exceed 5 mph.
Mist blowers and boom sprayers utilizing a controlled air flow to
facilitate particle sin and spray deposition may bi used at a vehicle
speed of 4 to 10 mph.
Mist blowers with a pump capable of producing up to 40 psi and
blower speeds of 2600 rpm are satisfactory. Use flat fan nozzles, 8001
to 8002, placed 30° into air blast or rotary atomizers into the air
blast that produce an efficient spray panicle with a mass medium
diameter of 40 to 100 microns. Swath widths should not exceed 30
fiet. and applications should not be made when winds exceed S mph.
EACH OF CHILDREN
iflNG, INHALATION OR SKIN CONTACT
Avoid Breathing Spray Mist
Avoid Contact With Skin
Wash Thoroughly After Handling
Change Contaminated Clothing
Do Not Contaminate Food Or Feed Products
PRECAUCldN
AL USUARIO: Si usted no lee ingles, no use este producto hasta
que la etiqueta le haya sido explicado ampliamente.
(TO THE USER: If you cannot read English, do not use this
product until the label has been fully explained to you.)
IN CASE OF AN EMERGENCY ENDANGERING LIFE OR PROPERTY INVOLVING
THIS PRODUCT. CALL COLLECT, DAY OR NIGHT. AREA CODE 201-835-3100.
Boom sprayers with a filtered rotary air compressor, either FTO or gas
engine driven or an air pump capable of producing at leest 12 psi are
satisfactory. Use air pressure on chemical tanks and an accurate
metering valve to assure a calibrated flow of the pesticide. Air should
be regulated with relief valve end gauge for proper air and liquid
mixture. Pneumatic-type spray nozzles, as suggested by equipment
manufacturer, should be used for spray panicles with mass medium
diameter of 30 to 100 microns. Applications should not be made
when winds exceed 5 mph.
Repeat applications should be made as necessary unless otherwise
specified.
aj Label of American Cyanamid Company, Princeton, New Jersey.
Nos. 241-208AA and 241-110AA.
EPA Registration
214
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Table 27. (Continued)
IMPORTANT
Undiluted spray droplets of MALATHION will permanently damage automobile paint. Cars should not be sprayed. If acci-
dental exposure does occur, the car should be washed immediately. Consult your state experiment station or state extension
service for proper timing of sprays.
This product is highly toxic to bees exposed to direct treatment. Protective information may be obtained from your Cooperative
Agricultural Extension Service.
CROP
Alfalfa
Beans (lima, green, snap. Navy,
red kidney, wax, dry, black-
eye)
Blueberries
Cherries
Cereal Crops, (barley, corn, oats,
wheat) and grasses
Clover, Pasture and Range
Grass, Grass, Grass Hay,
Nonagricultural Land
(wastelands, roadsides, soil
bank lands)
Corn
Cotton
Grain Crops (barley, corn, oats,
rye, rice, grain sorghum and
wheat)
PESTS
CONTROLLED
Alfalfa caterpillar
Western yellow
striped armyworm
Alfalfa weevil larvae
Beet armyworm
Grasshoppers
FLUID OUNCES
PER ACRE
8-12
16
8-16
8
INTERVAL BETWEEN LAST
APPLICATION AND HARVEST
Use lower rate when larvae are small. May be
applied on day of harvest or grazing. Use
higher rate when larvae are large or when
alfalfa is thick. 5 days.
5 days. Apply when day temperatures are
expected to exceed 65°F. and when 50-70%
of leaves show feeding damage.
Use lower rate when larvae are small. May be
applied on day of harvest or grazing. Use
higher rate when larvae are large or when
alfalfa is thick. 5 days.
May be applied on day of harvest or
grazing.
Do not apply to alfalfa in bloom. Do not apply to seed alfalfa.
Mexican Bean Beetle
Leafhoppers
Green Cloverworm
Japanese Beetle
Lygus Bug
Blueberry Maggot
Cherry Fruit Fly
Cereal leaf beetle
Grasshoppers
Adult Corn Rootworm
Early Season Insects
Thrips.
Fleahoppers
Leafhoppers
Boll Weevil
Grasshoppers
Lygus Bugs
Grasshoppers
8
10
12-16
4-8
8
4
4-8
8-12
16
8
8-12
16
8
Iday.
Oday.
1 day. Apply by aircraft only. Use higher rate
when foliage is heavy or infestation is severe.
Make first application as soon as flies appear.
Barley, oats, wheat: 7 days of harvest or forage
use. Corn: 5 days. Grasses: May be applied on
day of harvest or grazing.
May be applied on day of harvest or
Do not apply to clover in bloom.
grazing.
5 days.
\
Early to midseason
Diapause Weevil control • late season
Very heavy migrating populations.
> Oday.
7 days. Corn: 5 days of harvest or forage use.
215
-------
Table 27. (Continued)
CROP
Grain Sorghum
Rice - Grain Form
(Louisiana, Texas)
Safflowar
Soybean!
Sugar Beets
Nonagricultural Lands
Beef Cattle-Feed Lots and
Holding Pans
PESTS
CONTROLLED
Sorghum Midge
Rice Stink Bug
Grasshoppers
Lygus Bugs
Mexican Bean Beetle
Grasshoppers
Japanese Beetle
Green Cloverworm
Grasshoppers
Sugar Beet Root
Maggot Adults
Beet Leafhopper
(on wild host plants)
Adult flies and
Mosquitoes
FLUID OUNCES
PER ACRE
8-12
8
8
8
8
8
6-8
INTERVAL BETWEEN LAST
APPLICATION AND HARVEST
Apply during the bloom stage. 7 days of
harvest or forage use.
7 days. Apply by aircraft only. Apply
during early milk and dough stage of
growing rice.
3 days of harvesting seeds.
7 days of harvest or forage use.
7 days if tops are to be used as feed.
Oday.
Oday.
OTHER AGRICULTURAL USES
Alfalfa, Clover, Pasture and Range Grass, Grass, and Grass Hay, Grain Crops, Beans. Rice, Tomatoes and Nonagricultural Lands
(wastelands, soil bank lands): Adult mosquitoes and flies. Apply MALATHION at the rate of 2 to 4 fluid ounces for control of
adult mosquitoes and at 6 to 8 fluid ounces per acre for control of adult flies and mosquitoes. Repeat applications as necessary.
On alfalfa, clover, pasture and range grass, grass, and grass hay, may be applied on day of harvest or grazing. Do not apply to
alfalfa and clover in bloom. Do not use on seed alfalfa. On grain crops, make no application within 7 days of harvest or forage
use; on corn, within 5 days of harvest or forage; on rice, within 7 days of harvest; on beans and tomatoes, within 1 day of harvest.
FOREST INSECTS
Apply with aircraft equipped for ultra low volume application. Make application when air is calm and temperature is below
68°F. Do not allow spray to contact ferns, hickory and maples as injury may result. Do not spray on elms under extreme
heat, drought and disease conditions.
TREE
Douglas Fir
True Fir
Spruce
Hemlock
Pinei
Larch
PESTS
CONTROLLED
Spruce Budworm
Hemlock Looper
European Pine Sawfly
Saratoga Spittlebug
Larch Casebearer
FLUID OUNCES
PER ACRE
13
8
10
8
DIRECTIONS
Apply when highest percentage of larvae are
in the fifth instar.
Apply when most larvae are in third and
fourth instar.
Apply when larvae are in the first or second
instar or before they reach % in length.
Apply when 95% of the population has
become adult.
Apply in spring as soon as larvae break hiber-
nation and begin feeding on new foliage.
Before using CYTHION or MALATHION for the preparation of malathion insecticides, manufacturers should consult
American Cyanamid Company for manufacturing and safe handling instructions.
The Sale of this product does not include a license under any patent owned by American Cyanamid Company.
216
-------
The Tariff Commission report does not list the production and sales
volumes of malathion individually. Malathion is included in a group con-
sisting of seven other specified, and additional unspecified, acyclic
organophosphate insecticides. The reported production volume for this
composite group in 1972 was 65,181,000 Ib of active ingredients.
Through a process of careful analysis of the use patterns of all
organophosphate insecticides in this group supported by information
from confidential trade sources, Midwest Research Institute.!/ developed
estimates on the volume of production of all major products in the
group. The estimated volume of production of malathion in 1972 is
24 million pounds of active ingredient.
Imports - Imports of pesticides that are classified as "benzenoid chemi-
cals" are reported in a U.S. Tariff Commission annual report covering FY72.2/
Malathion, an aliphatic chemical, is also covered in the report. According
to the Tariff Commission, 153,769 Ib of malathion were imported into the
United States in 1972.
o /
Exports - Pesticide exports are reported by the Bureau of the Census^'
annually. Technical (unformulated) malathion is included in this report
in Section 512.0659, a category including all technical organic phosphate
insecticides except parathion and methyl parathion.
Formulations of malathion (and of all other organic phosphate insec-
ticides) are included in Schedule B, Section 599.2035, entitled "Organic
Phosphate Containing Pesticidal Preparations, Except Household and Indus-
trial and Except Fly Sprays and Aerosols."
Total exports of organic phosphate insecticides in these two cate-
gories for 1972 were as follows:
Section 512.0659 (technical organic phosphate 32,380,470 Ib
insecticides other than parathion and methyl
parathion)
Section 599.2035 (organic phosphate containing 15,898,884 Ib
formulations)
JL/ Midwest Research Institute/RvR Consultants, "Production, Distribution,
Use, and Environmental Impact Potential of Selected Pesticides,"
Council on Environmental Quality, Contract No. EQC-311, (August 1,
1974).
2/ U.S. Tariff Commission, Imports of Benzenoid Chemicals and Products,
TC Publication 601 (1973).
3_/ U.S. Bureau pf Census, U.S. Exports, Schedule B, Commodity by Country,
Report FT 410.
217
-------
To derive the 1972 export volume of malathion from these composite
totals, Midwest Research Institute made a thorough analysis of these
two pesticide export categories by unit dollar values and by countries
of destination. In the next step, this information was matched against
known crop protection problems and the pesticide trading patterns of
the countries of destination. Additional information was obtained
from confidential trade contacts, from the U.S. Agency for International
Development (AID), as well as from other sources. Based on all data
and information obtained from these sources, 1972 export volume of
malathion is estimated to be 8.0 million pounds of active ingredient.
Domestic Supply - On the basis of the data presented in the preceding
three sections, the domestic supply of malathion in the United States in
1972 was as follows:
Quantity
(Million Ib AI)
U.S. production
Imports
Exports
Domestic supply
Formulations - Malathion is available to users in the United States in a
variety of different formulations, including emulsifiable liquids, wet-
table powders, dusts, solutions, concentrates for low volume (LV) and
ultra-low volume (ULV) applications, and manufacturing concentrates.
The basic producer of malathion sells a substantial share of his produc-
tion to formulator-customers in the form of technical or manufacturing
concentrates. Formulators then prepare and sell formulations containing
malathion under their own labels and brand names to end users, either
directly or through wholesalers and/or retailers.
Frear (1972)!' lists the following pesticide products containing
malathion as the only active ingredient:
1. 151 sprayable formulations (emulsifiable liquids, wettable
powders, solutions, LV and ULV concentrates)
2. 38 dusts
3. 1 granular formulation
4. 11 manufacturing concentrates
\J Frear, D. E. H., Pesticide Handbook-Entoma, 24th Edition, College
Science Publishers, State College, Pennsylvania (1972).
218
-------
In addition to these products containing malathion as the only
active ingredient, a number of liquid and dry formulations are offered
that contain malathion in combination with other insecticides and/or
fungicides.
The most widely used formulations of malathion are the ULV concen-
trate containing 95% of active ingredient (9.7 Ib Al/gal), applied by
ground or air equipment; and the 57% (5 Ib Al/gal) emulsifiable liquid.
These two formulations combined account for a large share of the total
volume of use of malathion.
Use Patterns of Malathion in the United States
General - Agricultural and home and garden uses of malathion each
accounted for almost one-third of the estimated domestic use of
malathion in 1972, the balance consisting of industrial, commercial,
and governmental uses.
Table 29 summarizes the estimated uses of malathion in the United
States in 1972 by regions and major categories of use as determined in
that study, with the exception that an adjustment has been made in the
agricultural uses between the Southeastern and South Central states,
based on information received very recently.
Agricultural Uses of Malathion - Surveys on the use of pesticides by
farmers in the U.S. were conducted by the U.S. Department of Agriculture
in 1964, 1966, and 1971 (Agricultural Economic Reports No. 131, published
in 1968; No. 179, published in 1970; and No. 252, in press and soon to
be published). Data on the farm uses of malathion in 1972 were obtained
by RvR Consultants. Table 30 summarizes farm uses of malathion from
these surveys. It appears that the level of use of malathion on agri-
cultural crops, farm animals and for other farm uses has remained
relatively constant during the period in question, even though the
data from the two different sources are not directly comparable.
Table 31 presents a further breakdown of the farm uses of malathion
in 1972 by regions and by major crops, based on estimates developed by
RvR Consultants and on more recent studies.
219
-------
Table 28. ESTIMATED USES OF MALATHION IN THE U.S. BY REGIONS AND CATEGORIES, 1972
N>
1-0
O
Category
Industrial/ Government
Region
Northeast3./
North Centra lk/
Southeast^/
South Centra ll/
Northwest6./
Southwest^/
Total
Agriculture
200
1,000
1,050
1,050
700
1,000
5,000
commercial
(Thousands
800
1,200
800
800
200
200
4,000
agencies
of pounds
100
300
1,200
400
100
100
2,200
Subtotal
of active
1,100
2,500
3,050
2,250
1,000
1,300
11,200
Home and
garden
ingredient)
Geographic
distribution
not known
5,000
Total
16,200
aj New England States, New York, New Jersey, Pennsylvania.
b_/ Ohio, Indiana, Illinois, Michigan, Wisconsin, Minnesota, Iowa, Missouri,. North Dakota, South
Dakota, Nebraska, Kansas.
£/ Maryland, Delaware, Virginia, West Virginia, North Carolina, South Carolina, Georgia, Florida,
d/ Kentucky, Tennessee, Arkansas, Louisiana, Mississippi, Alabama, Oklahoma, Texas.
e/ Montana, Idaho, Wyoming, Colorado, Utah, Washington, Oregon, Arkansas.
fj New Mexico, Nevada, Arizona, California, Hawaii.
Source: MRI/RvR estimates. See text.
-------
Table 29. FARM USES OF MALATIIION IN THE U.S. IN
1964, 1966, 1971 AND 1972
Year
1972 1971 1966 1964
Source RvRg./ USDAk/ US DA US DA
(Thousands of pounds of active ingredient)
Crops 4,100 2,711 4,286 4,066
Livestock 700 652 735 602
Other farm uses 200 239 197 100
Total farm uses 5,000 3,602 5,218 4,768
a/ RvR estimates. See text.
b_/ U.S. Department of Agriculture Reports on quantities of pesticides
used by farmers, in 1964 (Agricultural Economic Report No. 131,
published 1968); in 1966 (Agricultural Economic Report No. 179,
published 1970); in 1971 (Agricultural Economic Report No. 252,
in press).
221
-------
NJ
(S3
to
Table 30.* ESTIMATED FARM USES OF MALATHION IN THE U.S. BY REGIONS AND MAJOR CROPS AND
OTHER USES, 1972
Region
Cotton
Other
field
crops
Forage,
crops, Fruit
rangeland crops
Crop
Other
Vegetables, farm
etc. Livestock uses
Total,
all f a rm
uses
r (Thousands of pounds of active ingredient)
NortheasdL/
Southeast]!/
North Centra l£/
South Cent rail/
Northwest^/
Southwest!/
Total, all regions
_ _
150
Negl.
650
__
100
900
Negl.
150
200
50
150
100
650
50
50
350
50
350
150
1,000
50
300
200
50
50
300
950
50
200
100
50
Negl.
200
600
50
150
150
150
100
100
700
Negl.
50
Negl.
50
50
50
200
200
1,050
1,000
1,050
700
1,000
5,000
*RvR estimates. See text.
a/ New England States, New York, New Jersey, Pennsylvania.
b/ Maryland, Delaware, Virginia, West Virginia, North Carolina, South Carolina, Georgia, Florida,
£/ Ohio, Indiana, Illinois, Michigan, Wisconsin, Minnesota, Iowa, Missouri, North Dakota, South
Dakota, Nebraska, Kansas.
d/ Kentucky, Tennessee, Arkansas, Louisiana, Mississippi, Alabama, Oklahoma, Texas.
e_/ Montana, Idaho, Wyoming, Colorado, Utah, Washington, Oregon, Arkansas.
if New Mexico, Nevada, Arizona, California, Hawaii.
-------
The following information sources were used in arriving at these
estimates:
1. The three USDA surveys of pesticide uses by farmers mentioned
above.
2. The annual USDA publication "Pesticide Review" (Agricultural
Stabilization and Conservation Service).
3. Results of a survey of the Federal/State Cooperative Extension
Services in all 50 states and in Puerto Rico conducted by RvR
Consultants in 1973.
4. Analyses of state pesticide use recommendations.
5. Local and regional estimates on pesticide use volumes obtained
from State Research and Extension personnel in personal
communications.
6. Pesticide use reports from the States of Arizona, California,
Illinois, Indiana, Michigan, Minnesota, and Wisconsin.
7. Data on pesticide uses supplied by the EPA Community Pesticide
Studies Projects in Arizona, Hawaii, Idaho, Mississippi, South
Carolina, Texas, and Utah.
8. Estimates and information obtained from basic producers of
malathion and other pesticides, and from pesticide trade sources.
9. Pesticide use surveys conducted recently by Wallaces * Farmer,
Des Moines, Iowa; Prairie Farmer, Chicago, Illinois; and
Wisconsin Agriculturist, Madison, Wisconsin.
10. "Agricultural Statistics," an annual publication of the U.S.
Department of Agriculture.
Data from all of these diverse sources were carefully analyzed,
correlated, cross-checked and cross-validated.
Farm uses of malathion by regions - It is estimated that about 5.0
million pounds of malathion AI were used in agriculture in the U.S. in
1972 (Table 31). The total quantity of malathion used by farmers was
distributed fairly evenly over all geographic regions, except the North-
eastern states where, it is estimated, only about 200,000 Ib of malathion
were used in 1972. The Northwestern states used an estimated 700,000 Ib,
whereas the remaining four regions each used about 1.0 million pounds.
223
-------
In all regions malathion was used on a variety of field, forage,
fruit, and vegetable crops; on livestock; and for the control of insects
in farm buildings and premises, including protection of stored grains,
feeds, other commodities, and for similar purposes.
Farm uses of malathion by crops - Analyzing the agricultural uses of
malathion by commodities (Table 31), it appears that no single crop
predominates. According to Midwest Research Institute estimates, the
use of malathion on forage crops and rangeland (against grasshoppers and
other insect pests affecting these crops) accounted for about 1.0 million
pounds AI, that is about 20% of all farm uses. About 350,000 Ib each
were used for these purposes in the North Central and Northwestern states;
about 150,000 Ib in the Southwest; the balance in the Northeastern, South-
eastern, and South Central states (50,000 Ib each).
Uses on fruit crops (including citrus fruits, deciduous tree fruits
and nuts, and all other fruits) accounted for another 20% of the total
farm use of malathion. About 300,000 Ib of malathion each were used in
the Southeastern and Southwestern states, followed by the North Central
(200,000 Ib), and the Northeastern, North Central and South Central states
(about 50,000 Ib each).
Approximately 900,000 Ib of malathion AI were used on cotton in 1972.
The largest share of this quantity was used in the South Central states,
in the diapause boll weevil control program in the high and rolling plains
of northern Texas. Smaller amounts of malathion were used on cotton in
the Southeastern and Southwestern states.
Approximately 650,000 Ib of malathion were used on field crops other
than cotton (including corn and other grains, soybeans, peanuts and
tobacco), and about 600,000 Ib on vegetable crops. In both categories,
the quantities used were distributed fairly evenly over all regions of
the country.
An estimated 700,000 Ib of malathion were used on livestock in 1972,
again distributed fairly evenly over all geographic regions.
Finally, an estimated 200,000 Ib were used for other purposes on
farms, including insect control in and around farm homes, other farm
buildings such as barns, milk rooms, feed processing areas, feedlots,
poultry houses, grain bins; for the protection of stored grains and other
farm commodities; for mosquito control in and around farm ponds; and for
similar uses.
224
-------
Industrial, Commercial, and Institutional Uses of Malathion - An esti-
mated 4.0 million pounds of malathion were used in 1972 by industrial,
commercial, and institutional organizations.
Malathion is used in this field against insects in food and beverage
processing, packaging and distributing establishments; in dairies; ware-
houses; and food-handling and -serving places such as bars, restaurants,
grocery stores, and meat markets.
Institutions such as hospitals, nursing homes, schools, museums,
and many others use malathion for the control of indoor as well as out-
door pests. Organizations responsible for outdoor gatherings of people
(drive-in theaters, recreational areas, picnic grounds, etc.) use mala-
thion against outdoor nuisance insects such as mosquitoes and flies.
In addition, malathion is used for the protection of stored products
in warehouses, bins, shiphoIds and many other'containers.
In many of the insect control situations described in the preceding
paragraphs, malathion is applied by professional pest control operators.
However, sizable quantities of malathion are also applied by commercial,
industrial and institutional organizations and their employees themselves,
since, due to its relatively low mammalian toxicity, the handling of
malathion does not require extraordinary safety equipment and precaution-
ary measures.
The estimated geographical distribution of the use of malathion for
industrial, commercial and institutional insect control purposes is out-
lined in Table 29. According to these estimates, the largest quantity
of malathion in this category is used in the North Central region, pri-
marily due to the extensive storage of food and feed grains in this area.
Governmental Agencies' Uses of Malathion - An estimated 2.2 million pounds
of malathion AI were used by Federal, state, regional, county, local, and
other governmental agencies in 1972. These estimates were developed by
Midwest Research Institute. Data sources used included several nationwide
surveys, expert consultants, and the Federal Working Group on Pest
Management.
Governmental agencies use malathion primarily for regional or area-
wide insect control purposes, such as mosquito control; control of in-
sects in quarantine programs (e.g., fruit flies, cereal leaf beetle);
areawide insect eradication or suppression programs (cotton boll weevil,
225
-------
grasshoppers); control of nuisance insects in public parks, recreation
areas and picnic grounds. Malathion is also used for the protection of
military and other governmental personnel and supplies from insects and
insect damage.
It is estimated that about 1.2 million pounds of malathion were
used by governmental agencies in the Southeastern states in 1972, which
is more than one-half of the total quantity (2.2 million pounds) used in
this category nationally. Malathion use by government agencies in the
South Central states is estimated at 400,000 Ib; in the North Central
states, 300,000 Ib; while the Northeastern, Northwestern and Southwestern
states each used about 100,000 Ib of malathion in governmental programs.
Home and Garden Uses of Malathion - It is estimated that about 5.0 mil-
lion pounds of malathion AI were used by home owners and amateur garden-
ers in the U.S. in 1972. The use patterns of malathion in this area
were not investigated in the MRI/RvR study on 25 selected pesticides.
No other published quantitative data is known to be available on nation-
wide home and garden pesticide uses.
Most probably, the use of malathion in and around homes and gardens
is relatively heavier in the Southern states because of the warmer
climate, longer vegetation season and greater abundance of home and gar-
den insects in these areas. However, malathion is also widely used in
the Northern states for home and garden insect control purposes.
Nearly all retail outlets for home and garden pesticides throughout
the entire U.S. carry one or more formulations containing malathion.
Malathion Uses in California - The State keeps detailed records of pes-
ticide uses by crops and commodities. The records are quarterly and
summarized annually. Table 32 summarizes major crop and other uses of
malathion in California for 1970 to 1973.
In California, malathion is not subject to the special restrictions
and reporting requirements imposed upon the sale and use of pesticides
designated as "injurious materials." For this reason, the percentage of
all malathion uses reported to the State Department of Agriculture and
included in its statistics is probably not as high as in the case of
restricted pesticides. However, the State Department of Agriculture and
others familiar with pesticide uses in California believe that the
Department's statistics do include a high percentage of the actual uses
of nonrestricted pesticides.
226
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Table 31* MALATHION USES IN CALIFORNIA BY MAJOR CROPS
AND OTHER USES, 1970-1973
Year
Croi
1973
1972
1971
1970
(thousands of pounds of active ingredient)
Citrus (oranges, lemons,
grapefruit)
Alfalfa, clover
Cotton
344
148
42
150
169
60
740
186
24
119
137
19
Safflower
Sugar beets
Beans
Melons (including watermelons)
Lettuce
Other farm uses (including
commercial ornamentals)
Vector control
Noncrop uses (including resi-
dential, industrial, struc-
tural pest control; uses by
governmental agencies)
Totals, all uses
19
17
32
14
135 .
103
79
89
29
20
49
83
60
121
62
119
39
10
33
41
94
70
222
22
16
41
12
112
89
11
522
1,022
922 1,462
1,100
California Department of Agriculture, Pesticide use reports for 1970,
1971, 1972 and 1973.
227
-------
According to these state reports (Table 32), the use of malathion
in California for all purposes varied between 922,000 Ib in 1972 and
1,462,000 Ib in 1971. There were even greater variations in the use of
malathion on individual crops between 1970 and 1973. For instance,
only 119,000 Ib of malathion were used on citrus in 1970, compared to
740,000 Ib in 1971. The quantities of malathion used on melons and on
lettuce, and for vector control also showed great variations between
years.
In 1970, 522,000 Ib of malathion were used for insect control pur-
poses other than farm uses and vector control. Of this quantity, 356,838
Ib are recorded as used on 224,304 acres not further identified. In all
probability, these 356,838 Ib were used primarily or entirely on farm
crops. This would bring the remaining quantity applied for noncrop uses
more in line with the quantities used in this category in the other 3
years.
Tables 33 and 34 present the malathion uses in California by crops
or other uses, number of applications, pounds of active ingredient, and
number of acres treated for 1972 and 1973, the two most recent years
for which such data are available. In both years, malathion was used in
California for about 120 to 130 different insect control purposes, includ-
ing use on over 100 different crops.
The California Department of Agriculture's malathion use statistics
cover primarily malathion uses by farmers and by governmental agencies.
They probably include only a smaller percentage of malathion uses by
industrial, commercial and institutional agencies, and in the home and
garden field.
At the present time, no other state records or publishes pesticide
use data in comparable detail. Limitations of time and resources avail-
able did not permit development of estimates on the uses of malathion by
states, crops, and other uses, beyond the detail provided in Tables 29,
30, and 31.
228
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Table 32. USE OF MAIATKLON IN CALIFORNIA IN 1972, BY CROPS,
APPLICATIONS, QUANTITIES, AND ACRES TREATED
Coinniodity
Applications
Lb
Acres*/
Alfalfa 928
Alfalfa for seed 122
Alroond 6
Apple 1
Apricot 1
Artichoke 6
Asparagus 38
Barley 1
Barn 2
Beans, dry edible 354
Beans, green or forage 12
P - Beans for sced^/ 3
Beet 8
Berries 3
M Birdsfoot, trefoil 1
vo Boysenberry 22
Broccoli 22
Brusscl sprout 1
Bushbcrrics 7
Cabbage 27
Cantaloupe 16
Carrot 20
Cattle lot 1
Cauliflower 23
Celery 458
Cherries, sweet 6
Chinese cabbage 2
Chives 14
Citrus 106
City agency
Clover 87
Clover for seed 7
Cole crops for seed 1
Conifer 1
Corn, field 64
Corn, sweet 4
Cotlon 307
County Agricultural Commissioner
136,996.29
19,521.00
1,838.96
2.50
9.60
261.28
4,862.47
37.00
30.26
47,841.68
778.66
3.93
532.46
187.85
62.48
588.43
913.79
6.15
179.00
1,092.18
72,507.90
5,322.58
7.23
718.20
10,433.45
181.22
20.24
474.50
12,643.27
3,330.53
11,878.08
572.39
1.02
19.43
1,013.03
750.81
60,454.61
176.91
83,766.80
16,778.00
173.50
4.00
24.00
204.00
4,145.00
70.00
1.50
27,554.00
549.00
7,874,400
318.00
109.00
40.00
289.50
700.05
6.00
119.00
653.00
2,488.00
539.50
10.00
616.00
7,277.13
66.00
18.00
146.00
2,2b7.09
9,154.00
375.00
1.00
35.00
960.00
109.00
57,353.00
Commodity Applications
County or city parks
County road
Cucumber or pickle 95
Date 171
Deciduous ornamental trees 4
End ivc 2
Federal agency
Fallow (open ground) 1
Flood control
Flowers 20
Foliage 2
Garlic 11
Grnnary 2
Grapefruit 26
Crape 44
Greenhouse 4
Hops 1
Industrial areas 1
Lemon 222
Lettuce, head 1,197
Lettuce, leaf 8
Lime 9
Livestock 1
Melons 30
Nectarine 6
Nonagrlcultural areas 9
Nursery stock 15
Olive 7
Onion, dry 111
Orange 1,398
Orn.imentals 79
Ornamental bedding plants 1
Other agencies
Pasture, rangcland 109
1'cncli 1.0
Pea 3
Pecan 1
Pepper, bell 2
Plum 4
Lb
Acreak/
2,020.24
128.83
3,737.92
5,645.25
150.11
18.67
617.42
54.09
549.95
239.03
148.51
856.57
0.16
1,582.89
6,404.10
144.97
80.00
8.20
12,864.90
59,632.29
128.23
28.26
20.95
2,532.14
132.00
244.07
3^6.54
175.68
7,110.44
135,676.94
724.18
0.04
10,762.59
19,085.33
633.89
102.20
3.84
43.13
43.04
2,536.50
1,737.00
94.10
9.00
37:00
115.99
85.00
606.00
0.02
322 . 50
1,975.50
47.00
80.00
16.00
3,782.33
37,854.97
86.75
6.15
20.00
2,265.00
48.00
339.70
178.80
85.00
4,030.50
31,764.88
442.76
0.60
30,537.00
110.85
77.00
3.00
-1.00
03.00
-------
T.-.blc 12.
IsJ
T -
Commodity
Potato
Prune
Pumpkin
Radish
Raspberry
Residential control
Residential control
Residential control
Rice
Roses
Ryegrass for seed
Safflower
School district
Sesame, seed
Sorghum
Spinach
Squash, summer
Squash, winter
State highway
Strawberry
Structural control
Subtropical fruits
• sudansrasj.
Sugar beet
Tangclo
Tangerine
Tomato
Turf
University of California
Vector control
Walnut
• Walnut
Water areas
Water resources
Watermelon
Wheat
Applications
6
1
25
1
1
2
2
3
2
181
1
8
14
27
8
39
1
1
193
3
2
51
2
33
1
9
26
2
Lb
419.46
1.92
940.06
25.14
88.23
31,985.56
18.46
30.00
67.19
7,633.46
434.95
29,194.07
646.46
32.83
757.18
319.41
1,255.35
209.31
242.77
2,661.19
77,733.93
16.35
14.46
19,599.05
168.00
511.25
6,982.39
171.64
104.02
61,605.40
767.53
0.50
111.27
3.90
8,331.00
20.82
Acres]*/ Footnotes
435.00 £/ Only agricultural applications are tabulated in this column.
12.00 b/ When the commodity listed is prefixed by ? or T, the amount listed in
607.00 the respective acreage column is not acreage but one of the follov-
12.00 ing, and is not included in total acreage.
20.00
P = Pounds
6.00 T = Number of trees
Source: State of California, Department of Agriculture, "Pesticide Use
62.50 Report" (1972). •
64.00
714.00
30,748.50
32.00
730.00
218.00
778.50
131.00
1,418.00
5.00
10.00
13,709.50
49.00
203.00
3,427.00
220.50
388.75
1
90.00
1,553.00
36.00
Total
6,938
922,034.02 392,048.22
-------
Table ?:i, USE OF MALATIttON IN CALIFORNIA IN 1973. BY CROPS,
APPLICATIONS, QUANTITIES, AND ACRES TREATED
Commodity
Alfalfa
Alfalfa for seed
Almond
Apple **
Apricot •
Artichoke
Asparagus
Avocado
Barley
Darn
Beans, dry edible
Deans, green or forage
Bc.ins for seed
P - Beans for seed-/
t-J
U) Hect
Berries
Boysenbcrry
Broccoli
Brussol sprout
Cabbayc
Cantaloupe
Carrot
Cattle, beef
L - Cattle, beef
Cattle lot
U - Cattle lot
Cauliflower
Celery
Cherries, sweet
Chinese cabbage
Chives
Citrus
City agency
Clover
Clover for seed
Collard
Conifer
Corn, field
Applications^/
1,030
88
3
6
2
5
47
2
7
1
315
2
1
5
33
5
28
24
4
70
31
29
1
15
1
1
19
423
2
3
4
44
81
5
1
1
45
Lb
116,708.81
17,953.22
1,040.74
272.00
15.77
3,405.36
6,526.50
8.80
280.07
0.10
31,950.92
24.17
79.96
3.53
1,786.31
144.66
755.71
808.16
11.20
3,926.03
6,203.43
1,622.69
0.43
63.84
1.00
1.76
147.50
10,944.12
50.50
71.00
59.49
3,597.23
2,161.02
13,361.61
428.76
1.00
701.78
763.21
AcresJL/
95,695.50
12,359.00
706.00
276.00
44.00
121.00
3,708.00
16.00
251.00
1.00
24,039.00
18.00
48.00
288,200
1,974.00
80.00
373.00
451.83
9.00
2,758.67
4,842.00
1,102.00
150.00
1,896
2.00
I
90.50
7,273.75
80.00
47.00
58.00
999.00
9,050.00
426.00
2.00
120.00
643.00
Commodity
Corn, sweet
Cotton
County Agricultural
County or city parks
Crcnshaw melon
Cucumber or pickle
Date
Deciduous ornamental
T - Deciduous ornamental
Implant
Evergreen trees and
Federal agency
Fallow (open ground)
Fig
Flowers
U - Flowers
Foliage
Garlic
U - Granary
Grapefruit
Crape
Greenhouse
U - Greenhouse
Honeydew melon
Hops
Industrial areas
U - Industrial areas
Lemon
Lettuce, head
Lettuce, leaf
Lime
T - Lime
L - Livestock
Melons
U - Miscellaneous
Mushroom
U - Mushroom
Mushroom house
U - Mushroom house
Applications
2
272
Commissioner
1
103
200
trees 1
trees 1
5
shrubs 2
4
21
77
3
5
3
6
27
99
2
1
1
4
8
9
146
1,388
21
I
5
2
53
1
9
3
3
7
Lb
11.18
41,878.13
226.38
2,056.10
40.84
3,062.03
5,071.00
2.05
2.56
14.22
13.75
751.35
59.57
17,798.00
643.67
5.60
37.43
295.73
79.19
37,703.98
3,571.74
71.94
0.16
120.00
368.00
137.94
76.13
66,841.55
134,060.21
617.83
0.96
14.59
4.85
5,685.15
1.08
107.12
1.03
1.40
4.SC
Acres!*/
43.00
37,495.50
40.00
2,023.61
1,643.50
2.00
6
13.00
11.00
45.25
4,759.00
240.80
19,031
27.75
171.00
8
373.00
2,717.50
25.00
1
80.00
368.00
321.00
209
2,923.50
72,972.53
340.00
0.50
494
1,585
4,676.75
9
169.12
81,000
2.33
7
-------
T:>l>; P Vt. (1'i.r.i I.MH'.-il;
Connodity Applications
Mustard green 2
Nectarine 2
Nonner (.cultural areas 7
Nursery stock' 8
U - Kursory stock 2
Oats 6
Olallicberry 1
01i ve 4
Onion, dry 143
Onion, green, spring, shallot 15
Oranj-.e 1,327
T - Orange 4
Ornamentals 34
•'"T - Ornamentals 1
(jj U - Ornamentals 3
1x2 Ornamental bedding plants 7
Other agencies
Pasture, rangeland 8
Poach 10
T - Peach 2
Pear 2
Pea 180
Pepper, bell 5
Plum 4
Pomegranate 1
Potato 24
U - Poultry house 3
Prune 4
Pumpkin 15
Raisin 1
Raspberry 2
Residential control
Residential control 2
T - Residential control 1
U - Residential control 1
Rice 3
Roses 2
Safflower 102
School district
Lb
Acreafe/ Commodity
2.08
15.13
135.22
411.04
3.07
86.10
4.38
181.87
9,597.66
19.98
236,188.84
15.49
196.16
8.30
24.90
53.25
21,092.68
1,458.82
628.88
6.00
4.96
572.60
17.87
58.93
350.89
2,511.41
12.00
83.90
302.31
232.00
38.31
30,583.70
2.75
0.75
6.60
326.71
31.40
19,057.45
323.54
2.50
12.00
151.03
170.38
101
347.00
4.00
65.00
5,766.00
21.99
34,036.51
341
50.50
10
37,500
12.73
2,321.00
119.50
33
4.00
534.70
13.85
58.00
80.00
1,682.00
43
267.00
266.00
145.00
14.00
3.50
1
44
386.00
21.00
20,218.00
L - Sheep and lambs
Sorghum
Spinach
Squash, summer
Squash, winter
State highway
Strawberry
Structural control
U - Structural control
Sugar beet
Sweet potato
L - Swine
Tangolo
Tangerine
Tomato
Turf
Turnip
University of California
Vector control
Vector control
Walnut
T - Walnut
Water areas
Water resources
Watercress
Watermelon
Wheat
Zucchini
Total
Applications
1
22
26
41
14
112
11
121
12
1
2
2
78
1
2
1
55
5
3
8
23
5
1
7,365
Lb
11.02
1,376.88
202.45
1,414.37
149.85
130.33
4,662.29
31,293.76
46.50
16,855.97
711.98
0.10
37.49
80.79
8,866.40
' 27.41
13.56
135.66
79,351.76
70.53
1,307.84
8.55
135.10
1.25
66.37
2,409.20
175.92
2.50
Acreak/
2,500
1,166.00
191.25
77i.50
111.50
2,714.00
338
11,079.00
266.00
9
12.00
90.00
2,266.39
100.00
12.50
100.00
718.98
20
270.00
39.00
1,967.00
20i.OO
2.00
1,021,715.49 388,205.40
a/ Only agricultural applications are tabulated in this column.
b/ When the commodity listed is prefixed by L, P, I', or T, the asounc
listed in the respective acreage column is not acreage but one of
the following, and is not included in total acre.-ujej
L = Number of livestock v = Miscellaneous units
1' = Pounds T = Nicr.ber of trees
Source: State of California, Department of Agriculture, "Pesticide L'se
Report" (1973).
-------
PART III. MINIECONOMIC REVIEW
CONTENTS
Page
Introduction 235
Cotton 237
Efficacy Against Pest Infestation 237
Cost Effectiveness of Pest Control 238
Sorghum 240
Efficacy Against Greenbug Infestation 240
Cost Effectiveness of Greenbug Control .... 241
Efficacy Against Sorghum Midge Infestation 242
Cost Effectiveness of Sorghum Midge Control 242
Soybeans 243
Sugar Beets 243
Forage Crops and Rangeland 243
Alfalfa 244
Rangeland 245
Fruits and Nuts 245
Cherries 245
Strawberries 246
233
-------
CONTENTS (Continued)
Page
Vegetables 246
Beans 247
Livestock 247
Nonagricultural Uses 248
References ' 249
234
-------
This section contains a general assessment of the efficacy and cost
effectiveness of malathion. Data on the production of malathion in the
United States as well as an analysis of its use patterns at the regional
level and by major crop, were conducted as part of the Scientific Review
(Part II) of the report. This section summarizes rather than interprets
scientific data reviewed.
Introduction
The efficacy and cost effectiveness of a specific pesticide should
be measurable in terms of the increased yield or improved quality of a
treated crop which in turn results in a greater income or lower cost
than would be achieved if the pesticide has not been used. Thus, one
should be able to pick an isolated test plot of a selected crop, treat
it with a pesticide, and compare its yield with that of a nearby un-
treated test plot. The difference in yield should be the increase due
to the use of the pesticide. The increased income (i.e., the yield
multiplied by the selling price of the commodity) less the additional
costs (i.e., the pesticide, its application and the harvesting of the
increased yield) is the economic benefit due to the use of the pesticide.
Unfortunately, this method has many limitations. The data derived
is incomplete and should be looked on with caution. A review of available
literature and EPA registration files revealed that experimental tests
comparing crops treated with specific pesticides to the same crop with-
out treatment are conducted by many of the state agricultural experi-
mental stations. Only a few of these, however, have attempted to
measure increased yield and most of this effort has been directed
toward just a few crops such as cotton, potatoes, alfalfa and selected
fruits. Most other tests on crops measure the amount of reduction in
pest levels which cannot be directly related to yield.
Even the test plot yield data are marginally reliable, since these
tests are conducted under actual field conditions that may never be
duplicated again and may not be representative of general field use.
Thus, yield is affected by rainfall, fertilizer use, severe weather
conditions, soil type, region of the country, pesticide infestation
levels and the rate, frequency and method of pesticide application.
Because of these factors, yield tests at different locations and
in different years will show a wide variance ranging from a yield decline
to significant increases. For example, in a year of heavy pest infesta-
tion, frequent pesticidal use can result in a high yield increase because
235
-------
the crop from the untreated test plot is practically destroyed. Conversely,
in a year of light (or in significint) infestation, the yield increase will
be slight (or undetectable),
Thus, the use of test plot yield data is at best qualitative and is
used for order-of-magnitude economic cost and benefit determination.
The use of market price to estimate the value received by the pro-
ducer also has its limitations, If the use of the pesticide increases
the yield of a crop and the national production is increased, then the
market price should decline, According to J, C, Headley and J. N, Lewis
(1967),!/ a 1% increase in quantity marketed has at times resulted in
a greater than 1% decrease in price, Thus, the marginal revenue from
the increased yield would be a better measure of value received.
A third limitation to the quantification of the economic costs and
benefits is the limited availability of data on the quantities of the
pesticide used by crop or pest, the acres treated, and the number of
applications. In most cases the amount of malathion used on each crop
or each pest is not available.
As a result of these limitations an overall economic benefit by
crop or pest cannot be determined. This report presents a range of
the potential economic benefits derived from the use of malathion to
control a specific pest on a specific crop. This economic benefit or
loss is measured in dollars per acre for the highest and lowest yield
increase developed from experimental tests conducted by the pesticide
producers and the state agricultural experimental stations. The high
and low yield increases are multiplied by the price of the crop and re-
duced by the cost of the malathion applied to generate the range of
economic benefits in dollars per acre.
Efficacy and yield changes due to the use of malathion have been
reported for a wide variety of pest-crop combinations. These include
the boll weevil on cotton; the grgenbug and sorghum midge on sorghum}
thi potato leafhopper on soybeans; the sugar beet maggot on sugar beetsj
the corn rootworm on corn; the alfalfa weevil on alfalfa; grasshoppers
on rangeland; ^e cherry fruit fly on cherries; the tarnished plant bug
I/ Headlty, J. C., and J. N, Lewis, The Pesticide Problem:An Economic
Aggggach to Public Policy. Resources for the Future, Inc., pp. 39-
AQ (1967).
236
-------
on strawberries; the mexican bean beetle on beans; the pea aphid on peas;
the potato aphid and leafhopper on potatoes; and the horn fly, stable fly
and other small insects on cattle.
Efficacy and yield changes have been evaluated due to the use of mala-
thion based on 1972 cost data. The results of these evaluations are sum-
marized in the following paragraphs.
Cotton
The use of malathion on cotton is primarily for control of the boll
weevil as it enters diapause. It is also recommended in some areas for
the control of thrips, two spotted spider mites and grasshoppers.
i
Efficacy Against Pest Infestation - The three major insects that attack
cotton are the tobacco budworm, the bollworm and the boll weevil. Malathion
is relatively ineffective against the budworm and bollworm and is not
recommended in some states for this use against those insects. In a test
of several organophosphate insecticides, Plapp (1971)±/ found that malathion
was not highly toxic to either the budworm or bollworm. Similar results
were obtained by Cowan and Davis (1968)17 who concluded that malathion did
not control bollworms or tobacco budworms.
Malathion has been found to be effective on the boll weevil as it
enters diapause. Lloyd et al, (197 2)3/ concluded that ULV formulations
of malathion gave effective control of boll weevils during tests con-
ducted in 1966 and 1967 in Carroll County and State College, Mississippi.
Applications of 0.25 to 0.50 Ib of malathion every 4 to 5 days provided
effective control. Cowan and Davis (1968) also concluded that ULV appli-
cations of malathion at 0.4 to 0.8 Ib/acre gave good control of the boll
weevil. These testa were conducted at Waco, Texas, in 1967.
JL/ Plapp, F. W., Jr,, "Insect Resistgnee in Heliothis; Tolerance in
Larvae of fl, virescens as Compared with H. gea to Organophosphate
Insecticides," J. Econ, jntgrnol.. 64:999-1002 (1971).
21 Cowan, C. B., Jr., and J. W. Davis., "Field Tests with Conventional
Low Volume and Ultra-Low-Volume Sprays for Control of the Boll
Weevil, Bollworm and Tobacco Budworm on Cotton in 1967," J. Econ.
Entomol.. 61:1115-1116 (1968).
j3/ Lloyd, E. P., J. P. McCoy, W. p. Scott, E. C. Burt, D, B, Smith, and
F. C. Tingle, "In-Season Control of the Boll Weevil with Uitra-
Low-Volume Sprays of Azinphosmethyl or Malathion," J. Econ. Entomol,
65:1153-1156 (1972).
237
-------
There appears to be little change in the efficacy of malathion to
the boll weevil. Namec and Adkisson (1968 to 1972)!/ have conducted
toxicity tests of insecticides to the boll weevil. Data since 1968 are
shown below.
Table 34. MALATHION EFFICACY TESTING RESULT ON BOLL WEEVILS
Insecticide
Malathion
Malathion
Malathion
Malathion
Malathion
Lb/acre
1.0
1.0
1.0
0.5
1.0
% kill (48 hr)
78
92
82
100
100
Year
1968
1969
1970
1971
1971
Cantu and Wolfenbarger'(1969 to 1972)!/ have conducted tests on the
toxicity of two spotted spider mites to malathion. The results as shown
below do not indicate any reduction in efficacy over a 4-year period.
Table 35. MALATHION EFFICACY TESTING RESULTS ON SPIDER MITES
Insecticide
Malathion
Malathion
Malathion
Malathion
Malathion
Malathion
Malathion
Malathion
concentration
(ppm)
0.25
0.01
0.25
0.01
0.25
0.01
0.25
0.01
kill after 72 hr
(foliar spray) Year
90 1969
27 1969
88 1970
24 1970
86 1971
20 1971
88 1972
20 1972
On the basis of these results it appears that there is no reduction
in the efficacy when malathion is used to control the boll weevil and two
spotted spider mites.
I/ Nemec, S. J., and P. L. Adkisson, "Laboratory Tests of Insecticides
for Bollworm, Tobacco Budworm and Boll Weevil Control," Investiga-
tions of Chemicals for Control of Cotton Insects in Texas (1968-1972)
7j Cantu, E., and D. A. Wolfenbarger, "Effectiveness of Experimental
Insecticides for Control of the Tobacco Budworm, Boll Weevil, Fall
Armyworm, and Two Spotted Spider Mites," Investigations of Chemicals
for Control of Cotton Insects in Texas (1969-1972).
238
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Cost Effectiveness of Pest Control - There have been a limited number of
studies on the change in cotton yield due only to the use of malathion.
It is most often used in mixtures with methyl parathion to control the
budworm and the boll weevil.
Yield increases from tests comparing malathion-treated cotton to
untreated test plots varied widely depending upon the number of applica-
tions and the degree of pest infestation. Data were only available from
seven tests conducted in Mississippi and Texas.
The wide range in yield increase is often due to the variance in
the rate of pest infestations. Pfrimmer et al. (1971)!/ reported that
during tests in 1969 a field that normally produced 1,500 to 2,000 Ib
of seed cotton per acre produced only one-tenth of the normal yield
without any insecticidal treatment.
The 1972 price received by farmers for cotton was 24.0
-------
The results of the yield tests are tabulated below.
Table 36. YIELD AND BENEFIT ANALYSIS RESULTS OF MALATHION ON SELECTED
COTTON PESTS
Application Yield
Rate increase
Date (lb Al/acre) No._ (Ib/acre)
1956
1956
1958
1967
1967
1967
1967
1.0
1.0
0.5
0.25
0.5
0.4
0.8
5
9
7
13
13
3
3
205
458
714
1,730
1,170
20
40
Additional
income
($/acre at
40.7c/lb)
83.45
186.41
290.60
704.11
476.19
8.14
16.28
Application
Cost at $1.20/lb
at $1.25/
effort
Economic
benefit
($)
12.25
22.05
12.95
20.15
24.05
2.19
3.63
7a.20
164.36
277.65
683.96
452.14
5.95
12.65
Source
£/
b/
a/ Bost, op. cit. (1974).
b/ Cowan et al., op. cit. (1968).
Sorghum
Malathion is registered for control of the sorghum midge, greenbug
and grasshoppers on sorghum. Of these, the greenbug and sorghum midge
are the two most important insects affecting yield.
Efficacy Against Greenbug Infestation - Although there are numerous insects
treated with malathion, perhaps the greenbug on sorghum is the most impor-
tant. Prior to 1968, the greenbug had been found mostly in small grains
such as wheat, barley and oats. However, in 1968 a new biotype emerged
and began infesting sorghum. Ward et al. (1970)i/ noted that in 1968, 7.3
million acres became infested resulting in a production loss estimated at
$20 million. Gate et al. (1973)2.7 reported that the Grain Sorghum Producers
Board estimated that $14 million was spent for control of grain sorghum
pests in 1970 compared with a total of only $100,000 spent prior to 1968.
Malathion has been found to be an effective insecticide against the greenbug.
Since the development of the biotype C greenbug infestation on
sorghum is recent, the efficacy data does not indicate any resistance to
malathion. Gate et al. (1973), in tests on sorghum in 1970, showed that
malathion applied at 1.0 Ib/acre gave a 97% seasonal control. Harvey
I/ Ward, C. R., E. W. Huddleston, D. Ashdown, J. C. Owens, and K. L. Polk,
"Greenbug Control on Grain Sorghum and the Effects of Tested Insecti-
cides on Other Insects," J. Econ. Entomol.. 63:1929-1934 (1970).
21 Gate, J. R., Jr., D. G. Bottrell, and G. L. Teets, "Management of the
Greenbug on Grain Sorghum. I. Testing Foliar Treatments of Insecti-
cides Against Greenbugs and Corn Leaf Aphids," J. Econ. Entomol.,
66:945-951 (1973).
240
-------
and Hackerott (1970)i/ detailed test results indicating 92% control 10
days after treatment.
Cost Effectiveness of Greenbug Control - The results of several tests in
Texas and Kansas show that yield increases varied from 243 Ib/acre to 1,479
Ib/acre when malathion-treated sorghum was compared to an untreated test
plot. The price of sorghum averaged $2.25/Cwt in 1972 (Agricultural
Statistics. 1973) and the cost of malathion was $1.20/lb (Bost, 1974). At
these prices and costs, the economic benefits would range from $3.09/acre
to $30.83/acre for the use of malathion to control the greenbug, while
application costs are $1.25 per treatment. These tests are summarized as
follows:
Table 37. YIELD AND BENEFIT ANALYSIS RESULTS OF MALATHIQN ON SORGHUM GREENBUGS
1968
1969
1970
1970
Application
(Ib Al/acre)
1.0 - milk
stage
1.0 - pre-
boot stage
1.25
0.94
0.25
1.0
Yield
increase
(Ib/acre)
1,479
270
293
243
533
666
Additional
income at
$2.25/Cst
($/acre)
33.28
6.08
6.59
5.47
11.99
14.99
Application
cost at $1.20/
Ib plus treat-
ment cost at
$125/effort
2.45
2.45
2.75
2.38
1.55
2.45
Economic
benefit
($) Source
30.83
3.63
3.84
3.09
10.44
12.54
a/
a/
£/
c/
a/ Harvey and Hackerott, op. cit. (1970).
b/ Ward et al., op. cit. (1970).
c/ Gate et al., op. cit. (1973).
Efficacy Against Sorghum Midge Infestation
Tests by American Cyanamid in Louisiana in 1972 concluded that malathion
gave excellent control of the sorghum midge (Barron, 1974).?/. Doer ing and
Randolph (1963)3/ also evaluated various insecticides against the midge and
found malathion to be effective.
^L/ Harvey, T. L., and H. L Hackerott, "Chemical Control of a Greenbug on
Sorghum and Infestation Effects on Yields," J. Econ. Entomol., 63:
1536-1539 (1970).
21 Barron, F. R., Manager, Plant Industry Registrations, American Cyanamid,
personal communication, Criteria and Evaluation Division, Environmental
Protection Agency (1974).
3/ Doering, G. W., -and N. M. Randolph, "Habits and Control of the Sorghum
Midge, Contarinia sorghicola, on Grain Sorghum," J. Econ. Entomol.,
56:454-459 (1963).
241
-------
Cost Effectiveness of Sorghum Midge Control
The above papers were the only ones which compared yields of malathion
treated sorghum plots against an untreated check. The results of which
these experiments showed yield increases ranging from 445 Ib/acre to 890
Ib/acre. The price of sorghum averaged $2.25/Cwt in 1972 (Agricultural
Statistics. 1973) and the cost of malathion was $1.20/lb (Bost, 1974).
At these prices and costs, the economic benefits would range from $8.81/
acre to $18.83/acre.
These tests are summarized below:
Table 38. MALATHION TREATMENT RESULTS ON SORGHUM MIDGE
Date
1960
1960
1972
Application
rate
(Ib Al/acre)
1.0
1.0
0.5
1.0
0.5
1.0
Yield
Increase
(Ib/acre)
890*
445+
638
871
630
617
Additional
increase
($/acre at
$2,25/Cwt)
20.03
10.01
14.36
19.60
14.18
13.88
Application
Cost at $1.20
16AI + $1.25/
treatment
cost
2.45
2.45
1.85
2.45
1.85
2.45
Economic
benefit
($) Source
17.58 £/
7.56 £/
12.51 b_/
17.15 b_/
12.33 b/
12.43 b/
Treated when 90% of the heads had emerged from boot.
+ Treated 4 days after 90% of heads had emerged from boot.
a/ Doering and Randolph, op. cit. (1963).
b_/ Barren, F. R., op. cit. (1974).
Soybeans
Ogunlana and Pedigo (1974).=.' reported that the potato leafhopper is
one of the most common insects on soybeans in Iowa, Ohio, Minnesota and
Missouri. Their tests showed that soybean yields declined up to 25.7
bushels/acre, depending upon the number of leafhoppers per plant and soy-
bean stage. They also report that Iowa farmers use malathion at a rate
of 1 Ib/acre to control the leafhopper.
The 1972 price of soybeans averaged $3.49/bushel (Agricultural
Statistics. 1973; costs of malathion were estimated at $1.20/lb (Bost, 1974),
application costs are $1.25 per treatment. At a yield increase of 25.7
bushels of beans per acre, the economic benefit would be $87.24/acre.
~\J Ogunlana, M. 0., and L. P. Pedigo, "Economic Injury Levels of the
Potato Leafhopper on Soybeans in Iowa," J. Econ. Entomol., 67:
29-32 (1974).
242
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Sugar Beets
Peay et al. (1969)—' evaluated granular and foliar insecticides for
control of the sugar beet maggot on sugar beets. In tests conducted in
Idaho in 1967, an application of 1.5 Ib/acre of malathion resulted in a
yield of 26.1 tons of sugar beets per acre, an increase of 3.3 tons over
an untreated check.
The average price for sugar beets in 1972 was $16/ton (Agricultural
Statistics. 1973); the cost of malathion was $1.20/lb (Host, 1974). At
these prices and costs the economic benefit from the use of malathion
would be $49.75/acre.
Forage Crops and Rahgeland
Approximately 1 million pounds of malathion were used in 1972 to
treat alfalfa, clover, grass, hay, pastures and rangeland. The major
crop pests are the alfalfa weevil and the grasshopper. The clover head
weevil has also occurred as a pest in East Texas.
Alfalfa - The alfalfa weevil was estimated to have caused a loss of
$17,430,000 in the North Central States in 1972 due to a combination of
yield losses and costs for applying controls (North Central, 1974)±/.
California in 1972 used 156,517 Ib of malathion on alfalfa (California,
1972)3/. These figures indicate a substantial problem due to the alfalfa
weevil.
Only two articles were found concerning malathion and the alfalfa
weevil. Goonewardene and Filmer (1971)J7-/ reported on tests conducted at
the New Jersey experimental station in Rutgers, New Jersey in 1959, which
indicated a yield decline when comparing malathion treated alfalfa to a
control. These results showed a decline in yield ranging from 200% to an
increase of 23%. The authors concluded that the differences in yield were
not significant.
I/ Peay, W. E., 6. W. Beards, and A. A. Swenson, "Field Evaluations of
Soil and Foliar Insecticides for Control of the Sugar Beet Root
Maggot." J. Econ. Entomol.. 62:1083-1087 (1969).
2f North Central Branch Insect Loss and Control Estimates Soc. 1972, pre-
pared by ESA North Central Branch Survey Entomologists (March 1974).
3/ California Department of Agriculture, Pesticide Use Report (1972).
kj Goonewardene, H. F., and R. S. Filmer, "A Technique for Evaluation of
Field Control of the Alfalfa Weevil Using a Fixed Population,"
J. Econ. Entomol., 64:327-328 (1971).
243
-------
Armbrust et al. (1968)—' conducted field and laboratory tests in 1967
on insecticides for alfalfa weevil control. In a test at Vincennes,
Indiana, a yield increase of 183% was recorded 21 days after application
of 1.25 Ib/acre of malathion and a 141% increase after 28 days occurred.
The authors concluded that malathion was effective in warm weather but
performed poorly in wet and cool weather.
The price of hay in 1972 averaged $31.40/ton and yields averaged
2.15 tons/acre (Agricultural Statistics, 1973). Based on the above data,
it can be assumed that the use of malathion ranged from no increase in
yield to an increase of 183% or 1.78 tons/acre when 1.25 Ib of malathion
were applied. The cost of malathion is $1.20/lb (Bost, 1974); application
costs are $1.25 per treatment. Economic benefits would range from $2.45
to $53.14/acre.
Rangeland - Grasshoppers on rangeland are often treated with malathion.
Skoog and Cowan (1968).?_/ estimated that 1,198,909 acres of grasshopper
infested rangeland were sprayed with malathion in 1965. Although no yield
information was obtained, the above authors showed that 8 oz/acre of
malathion aerially applied to rangeland reduced the grasshopper population
by 82.2% to 95.0% depending upon the size of spray and height of the
flight.
It has been estimated that the yield of grass from rangeland in
South Dakota is 0.6 ton/acre and has a value of $30/ton (Kantak, 1974)!/.
Losses due to grasshoppers are estimated at 35% of the crop which would
be equal to 400 Ib/acre or $6/acre. The cost of malathion at $1.20/lb
(Bost, 1974); application costs are $1.25 per treatment. With an applica-
tion of 0.5 Ib/acre the resulting economic benefit from using malathion on
rangeland would be $4.15/acre.
Fruits and Nuts
An estimated 950,000 Ib of malathion were used to treat fruit crops
in 1972. It is used primarily to control aphids, mites, fruits flies,
leafhoppers, and fruitworms.
I/ Armbrust, E. J., M. C. Wilson, and T. R. Hintz, "Chemical Control of
the Alfalfa Weevil in Illinois and Indiana. I. Comparison of Regis-
tered and Experimental Materials," J. Eeon. Entomol., 61:1050-1954
(1968).
21 Skoog, F. E., and E. T. Cowan, "Flight Height, Droplet Size and
Moisture Influence on Grasshopper Control Achieved with Malathion
Applied Aerially at ULV," J. Econ. Entomol., 61:1000-1003 (1968).
3/ Kantak, B. H., Extension Entomologist, Cooperative Extension Service,
Brookings, South Dakota, "Summary of Tests," personal communication
(1974).
244
-------
Cherries - Zwick et al. (1970)i' evaluated the use of ultra-low volume
(ULV) malathion aerial sprays to control the cherry fruit fly in The Dalles,
Oregon, in 1969. Two different tests showed that infestation rates varied
from 0 to 0.57% when malathion was applied. Comparably untreated fields
had infestations varying from 0 to 10.6%. These are summarized in the
following table:
Table 39. MALATHION ULV AERIAL APPLICATIONS FOR CHERRY FRUIT FLY CONTROL
(THE DALLES, OREGON, 1969, CHERRIES HARVESTED 18 JULY)
Amount No.
applied cherries "L
(oz/acre) Dates applied examined infested
8 5/21, 28; 6/2, 12, 25; 7/4, 13 4,813 0.04
0 Control£/ 2,031 3.15
8 5/21, 28; 6/2, 12, 26; 7/4, 13 2,294 0.09
0 Control^/ 2,006 1.60
8 5/21, 28; 6/2, 12, 26; 7/4, 13 3,607 0.00
0 Control*/ 2,643 0.00
a/ Recommended fruit fly applications made by growers until 22 to 25
June.
Table 40. MALATHION ULV AERIAL APPLICATIONS FOR CHERRY FRUIT FLY CONTROL
(EUGENE, OREGON, 1969)
Amount Date No.
applied No. harvested cherries °/a
(oz /acre) applications (July) examined infested
858 1,515 0.00
16 5 8 1,643 0.00
0 Control 8 1,306 0.54
8 5 17 1,752 0.57
16 5 17 1,105 0.00
0 Control 17 865 10.06
Since this reference did not give any indication of cherry yield
per acre, economic benefits from the use of malathion could not
be developed.
V Zwick, R. W., S. C. Jones, F. W. Peifer, R. W. Every, R. L. Smith
and J. R. Thiemes, "Malathion ULV Applications for Cherry Fruit
Fly Control," J. Econ. Entomol.. 65:1693-1695 (1970).
245
-------
Strawberries - Schaefers (1972)i/"evaluated malathion for control of the
tarnished plant bug on strawberries and concluded that application of
malathion at 1.0 Ib/acre 14 days after application of dimethoate would be
an effective program for control of this insect. These results are sum-
marized in Table 42.
/Table 41. CONTROL OF THE TARNISHED PLANT BUG ON STRAWBERRIES WITH MALATHION
Pesticide No. Percent Percent increase
and test Lb/acre Applications berries injury over untreated
(1) Malathion 1.0 2 11,547 24 57
Untreated -- — 11,981 81
(2) Malathion 1.0 3 3,061 14 54
Malathion 1.0 2 3,391 31 37
Malathion 1.0 3' 1,767 49 19
Untreated -- -- 2,200 68
(4) Malathion 1.0 2 8,619 25 30
Malathion 1.0 3 8,594 26 29
Malathion 1.0 1 8,938 48 7
Untreated -- — 8,652 55
(5) Malathion 1.0 1 2,314 33 38
Malathion — — 2,132 71
The,prices received for strawberries in 1972 averaged $24/cwt and
yields averaged 105 cwt/acre (Agricultural Statistics, 1973). The yield
increases from the above tests ranged from 6.3% to 3870. At a revenue
of $2,520/acre, the additional income at the above yield increases would
range from $158.76 to $806.40/acre. Subtracting the malathion cost of
$1.20/lb the economic benefit from its use would vary between $156.56
and $805.20/acre.
Vegetables
Approximately 600,000 Ib of malathion were used in 1972 to treat
insects on a broad variety of vegetables. It is primarily used to con-
trol aphids, leafhoppers, beetles and mites on crops such as beans,
lettuce, potatoes, cucumbers and melons.
\J Schaefers, G. A., "Insecticidal Evaluations for Reductions of Tarnished
Plant Bug Injury in Strawberries," J. Econ. Entomol., 65:1156-1160
(1972).
246
-------
A limited amount of yield data were developed from the literature.
Beans - One study compared the yield of beans when treated with malathion
to an untreated test plot for control of the Mexican bean bettle. Smith
and Corley (1972)i/ found that the yield of snap beans when treated with
six applications of malathion at a rate of 2.0 Ib/acre was 5,710 Ib/acre.
An untreated check plot yielded 2,552 Ib and had feeding injury to 100%
of the plants.
Snap beans in 1972 averaged 14.5<:/lb (Agricultural Statistics, 1973).
This yield increase of 3,158 Ib/acre at 14.5c/lb of beans would result
in additional revenues of $457.87/acre. Subtracting the cost of mala-
thion at $1.20/lb (Bost, 1974) would result in an economic benefit of
$443.47/acre when malathion was used to control the bean beetle.
Livestock
Malathion was used at a rate of 700,000 Ib in 1972 to control a wide
variety of insects on livestock and poultry. It is primarily used to
control the horn fly on cattle but is also used on stable flies, face
flies, mosquitoes, chiggers, lice, ticks, mites and fleas.
The horn fly is one of the most damaging cattle pests especially
in southern areas. Most ranchers consider chemical control of this
pest good management. Application is most often by the use of insec-
ticide treated backrubbers or by aerial application of ULV sprays.
Kinzer (1970).?./ found that ground applications of ULV malathion at a
rate of 0.38 oz/animal provided 83% control after 2 days and 59% after
7 days. Dobson and Sanders (1965)<3/ concluded that aerial applications
of 8 oz ULV malathion provided satisfactory horn fly control in Indiana
for 1 week after treatment.
Balsbaugh et al. (1970)4/ found that malathion gave the best control
of horn flies after the second day but was poorest at the end of 1 week
when compared to four other pesticides.
I/ Smith, F. F., and C. Corley, "Mexican Bean Beetle, Yields and Residues
of Malathion Sprays on Snap Beans," J. Econ. Entomol., 65:288-289
(1972).
2/ Kinzer, H. G., "Ground Applications of Ultra-Low-Volume Malathion and
Fenthion for Horn Fly Control in New Mexico," J. Econ. Entomol., 63:
736-739 (1970).
3_/ Dobson, R. C., and D. P. Sanders, "Low-Volume-High Concentration
Spraying for Hornfly and Face Fly Control on Beef Cattle," J. Econ.
Entomol.. 58:379 (1965).
4_/ Balsbaugh, E. U.', Jr., G. A. Alleman, B. H. Kantack, and W. L. Berndt,
"Aerial Application of ULV Organic Phosphate Insecticides for Control-
ling Livestock Insect Pests," J. Econ. Entomol., 63:548-551 (1970).
247
-------
Eschle and Miller (1968)i/ concluded that ULV applications of
malathion to dairy cattle daily were effective in controlling the
horn fly at a cost of 0.064c/animal/day. Kinzer (1969)2/ estimated
a cost of 61C/animal for aerial application of malathion and would
require an application about once a week to be effective.
Kantak et al. (1967).3/ estimated the seasonal cost of ULV malathion
aerial spray would vary from $1.50 to $3.66/year.
The horn fly has been reported to cause a weight loss in cattle.
Laake (1946)_t/ reported that cattle protected from heavy populations of
horn flies have shown a gain of 30 to 70 Ib/animal more than untreated
cattle.
The price of cattle in 1972 averaged $33.50/cwt (Agricultural
Statistics, 1973). Assuming an average additional gain of 30 to 70 Ib
for treated cattle, this would produce an additional income of $10.05
to $23.45/head. Subtracting costs of applying malathion of $1.50 to
$3.66/year, the economic benefit would range from $6.39 to $21.95/head
for each pound of malathion applied.
Nonagricultural Uses
Approximately 11,400,000 Ib of malathion are used by industrial,
commercial, institutional and governmental organizations, and by indi-
vidual consumers. Because of the wide range of uses, economic values
of pesticidal use are difficult to determine. Much of the use is in
areas that provide aesthetic benefits such as the control of mosquitos
and flies or the treatment of ornamentals around the house, industrial
or commercial sites. Economic benefits are derived by the home gardener
who uses malathion on vegetables and fruits since his increased yield
represents a savings over grocery purchases.
The control of mosquitos by governmental or private agencies may
be an economic benefit because of the reduction in disease to human
beings. However, the limits of this study do not permit the time to
explore this area.
I/Eschle, J. L., and A. Miller, "Ultra-Low-Volume Application of Insecti-
cides to Cattle for Control of the Horn Fly," J. Econ. Entomol., 61:
1617-1621 (1968).
2J Kinzer, H. G., "Aerial Applications of Ultra-Low-Volume Insecticides
to Control the Horn Fly on Unrestrained Range Cattle," J. Econ.
Entomol., 62:1515-1516 (1969).
3/ Kantak, B. H., W. L. Berndt, and E. U. Balsbaugh, Jr., "Horn Fly and
Face Fly Control of Range Cattle with Ultra-Low-Volume Malathion
Sprays," J. Econ. Entomol., 60:1766-1767 (1967).
47 Laake, E. W., "DDT for the Control of the Horn Fly in Kansas," J. Econ.
Entomol., 39:65-68 (1946).
248
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References
Armbrust, E. J., M. C. Wilson, and T. R. Hintz, "Chemical Control of
the Alfalfa Weevil in Illinois and Indiana. I. Comparison of Regis-
tered and Experimental Materials," J. Econ. Entomol.. 61:1050-1054
(1968).
Balslsaugh, E. U., Jr., G. A. Alleman, B. H. Kantack, and W. L. Berndt,
"Aerial Application of ULV Organic Phosphate Insecticides for Control-
ling Livestock Insect Pests," J. Econ. Entomol., 63:548-551 (1970).
Barren, F. R. (Manager, Plant Industry Registrations, American Cyanamld)
personal correspondence to Dr. H. Fairchild, Criteria and Evaluation
Division, Environmental Protection Agency (1974).
Bost, W. M., Director, Cooperative Extension Service, Mississippi State,
Mississippi, personal letter to D. F. Hahlen (1974).
California Department of Agriculture, Pesticide Use Report (1972).
Cantu, E., and D. A. Wolfenbarger, "Effectiveness of Experimental Insec-
ticides for Control of the Tobacco Budworm, Boll Weevil, Fall Armyworm,
and Two Spotted Spider Mites," Investigations of Chemicals for Control
of Cotton Insects in Texas (1969-1972).
Gate, J. R. , Jr., D. G. Bottrell, and G. L. Teets, "Management of the
Greenbug on Grain Sorghum. I. Testing Foliar Treatments of Insecti-
cides Against Greenbugs and Corn Leaf Aphids," J. Econ. Entomol., 66:
945-951 (1973).
Cowan, C. B., Jr., and J. W. Davis, "Field Tests with Conventional Low
Volume and Ultra-Low-Volume Sprays for Control of the Boll Weevil
Bollworm and Tobacco Budworm on Cotton in 1967," J. Econ. Entomol..,
61:1115-1116 (1968).
Dobson, R. C., and D. P. Sanders, "Low-Volume-High Concentration Spraying
for Hornfly and Face Fly Control on Beef Cattle," J. Econ. Entomol..
58:379 (1965).
Doering, G. W., and N. M. Randolph, "Habits and Control of the Sorghum
Midge, Contarinia sorghicola, on Grain Sorghum," J. Econ. Entomol.,
56:454-459 (1963).
249
-------
Eschle, J. L., and A. Miller, "Ultra-Low-Volume Application of Insecticides
to Cattle for Control of the Horn Fly," J. Econ. Entomol., 61:1617-1621
(1968).
Goonewardene, H. F., and R. S. Filmer, "A Technique for Evaluation of
Field Control of the Alfalfa Weevil Using a Fixed Population," J. Econ.
Entomol., 64:327-328 (1971).
Harvey, T. L., and H. L. Hackerott, "Chemical Control of a Greenbug on
Sorghum and Infestation Effects on Yields," J. Econ. Entomol., 63:
1536-1539 (1970).
Headley, J. C., and J. N. Lewis, The Pesticide Problem: An Economic
Approach to Public Policy, Resources for the Future, Inc., pp. 39-40
(1967).
Kantak, B. H., Extension Entomologist, Cooperative Extension Service,
Brookings, South Dakota, "Summary of Tests," personal correspondence
to D. F. Hahlen (1974).
Kantak, B. H., W. L. Berndt, and E. U. Balsbaugh, Jr., "Horn Fly and
Face Fly Control of Range Cattle with Ultra-Low-Volume Malathion
Sprays," J. Econ. Entomol., 60:1766-1767 (1967^.
Kinzer, H. G., "Aerial Applications of Ultra-Low-Volume Insecticides
to Control the Horn Fly on Unrestrained Range Cattle," J. Econ.
Entomol.. 62:1515-1516 (1969).
Kinzer, H. G., "Ground Applications of Ultra-Low-Volume Malathion and
Fenthion for Horn Fly Control in New Mexico," J. Econ. Entomol., 63:
736-739 (1970).
Laake, E. W., "DDT for the Control of the Horn Fly in Kansas," J. Econ.
Entomol., ,39:65-68 (1946).
Lloyd, E. P., J. P. McCoy, W. P. Scott, E. C. Burt, D. B. Smith, and
F. C. Tingle, "In-Season Control of the Boll Weevil with Ultra-Low-
Volume Sprays of Azinphosmethyl or Malathion," J. Econ. Entomol.,
65:1153-1156 (1972).
Nemec, S. J., and P. L. Adkisson, "Laboratory Tests of Insecticides for
Bollworm, Tobacco Budworm and Boll Weevil Control," Investigations of
Chemicals for Control of Cotton Insects in Texas (1968-1972).
North Central Branch Insect Loss and Control Estimates Soc. 1972, prepared
by Entomalogical Society of America, North Central Branch Survey
Entomologists (March 1974).
250
-------
Ogunlana, M. 0., and L. P. Pedigo, "Economic Injury Levels of the Potato
Leafhopper on Soybeans in Iowa," J. Econ. Entomol., 67:29-32 (1974).
Peay, W. E., G. W. Beards, and A. A. Swenson, "Field Evaluations of Soil
and Foliar Insecticides for Control of the Sugar Beet Root Maggot,"
J. Econ. Entomol., 62:1083-1087 (1969).
Pfrimmer, T. R., R. E. Furr, and E. A. Stadelbocher, "Materials for
Control of Boll Weevils, Bollworms, and Tobacco Budworms on Cotton
at Stoneville, Mississippi," J. Econ. Entomol., 64:475-478 (1971).
Plapp, F. W., Jr., "Insect Resistence in Heliothis: Tolerance in Larvae
of H. virescens as Compared with H. zea to Organophosphate Insecti-
cides," J. Econ. Entomol., 64:999-1002 (1971).
SchaeferSj G. A., "Insecticidal Evaluations for Reductions of Tarnished
Plant Bug Injury in Strawberries," J. Econ. Entomol., 65:1156-1160
(1972).
Skoog, F. E., and E. T. Cowan, "Flight Height, Droplet Size and Moisture
Influence on Grasshopper Control Achieved with Malathion Applied
Aerially at ULV," J. Econ. Entomol., 61:1000-1003 (1968).
Smith, F. F., and C. Corley, "Mexican Bean Beetle, Yields and Residues
of Malathion Sprays on Snap Beans," J. Econ. Entomol.. 65:288-289
(1972).
U.S. Department of Agriculture, Agricultural Statistics 1973.
U.S. Bureau of the Census, U.S. Exports, Schedule B, Commodity By Country,
Report FT 410.
U.S. Tariff Commission, Impacts of Benzenoid Chemicals and Other Products,
TC Publication (601) 1973.
U.S. Tariff Commission, Synthetic Organic Chemicals, U.S. Production and
Sales, 1972, TC Publication 681 (1973).
Ward, C. R., E. W. Huddleston, D. Ashdown, J. C. Owens, and K. L. Polk,
"Greenbug Control on Grain Sorghum and the Effects of Tested Insecti-
cides on Other Insects," J. Econ. Entomol., 63:1929-1934 (1970).
Zwick, R. W., S. C. Jones, F. W. Peifer, R. W. Every, R. L. Smith, and
J. R. Thiemes, J'Malathion ULV Applications for Cherry Fruit Fly
Control," J. Econ. Entomol., 65:1693-1695 (1970).
•tr U.S. GOVERNMENT PRINTING OfFIC&1975- 210-810/23
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