SUBSTITUTE CHEMICAL PROGRAM
INITIAL SCIENTIFIC
MINIECONOMIC REVIEW
METHYL PARATHION
FEBRUARY 1975
U.S. ENVIRONMENTAL PROTECTION AGENCY
OFFICE OF PESTICIDE PROGRAMS
CRITERIA AND EVALUATION DIVISION
WASHINGTON, D.C. 20460
i
EPA-540/1-75-004
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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 necessarily reflect
the views and policies of the Environmental
Protection Agency, nor does mention of trade
names or commercial products constitute endorse-
ment 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 cKemicals." 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 litigation
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 Methyl Parathion (0,0)-dimethyl 0-p_-nitrophenyl phosphorothioate).
Methyl parathion 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.
iii
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The review covers all uses of methyl parathion and is intended to
be adaptable to future needs. Should methyl parathion 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 to be complete in all areas. The review
was coordinated by a team of EPA scientists in the Criteria and Evalua-
tion Division of the Office of Pesticide Programs. The responsibility
of the team leader was to provide guidance and direction and technically
review information retrieved during the course of the study. The
following EPA scientists were members of the review team: William
Burnam, (Pharmacology and Toxicology), team leader; Merry L. Alexander
(Chemistry), Howard Kerby, Ph.D. (Fate and Significance in the Environ-
ment) ; inomas Freitag (Fate and Significance in the Environment); Ellis
Thomas, Ph.D. (Registered Uses); Jeff Conopask (Economics); Richard
Simpson (Economics).
Data research, abstracting and collection was 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. Manufacturers of
methyl parathion (Kerr McGee, Stauffer, Monsanto and Helena) made
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: Pesticide and
Toxic Substances Effects Laboratory, Research Triangle Park, North
Carolina; Gulf Breeze Environmental Research Laboratory, Gulf Breeze,
Florida.
iv
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GENERAL CONTENTS
Page
List
List
Part
Part
I.
II.
Subpart A.
Subpart B.
Subpart C.
Subpart D.
* .
t
Initial Scientific Review
Fate and Significance in the Environment
vi
vii
1
9
9
46
84
122
Part III.
Minieconomic Review
156
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FIGURES
No. Page
1 Production Schematic for Methyl Parathion 15
2 Thermal Isomerization of Methyl Parathion 23
3 General Scheme for Multiple Residues 28
4 Analytical Scheme for Chlorinated (Nonionic)
and Organophosphate Residues ..... 29
vi
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TABLES
No. Page
1 Raw Materials and By-Products in the Manufacture
of Methyl Parathion by Monsanto 16
2 Suggested Formulations for Methyl Parathion
Emulsifiable Concentrates 19
3 Percent Distribution of Methyl Parathion Residues
By Fiscal Year in Different Quantitative Ranges 37
4 Summary of U.S. Tolerances for Methyl Parathion
and/or Parathion on Raw Agricultural Commodities .... 41
5 Acute Oral Toxicity - Rats 49
6 Acute Toxicity Rats - Routes Other Than Oral 50
7 Acute Oral Toxicity - Mice 51
8 Toxicity of Methyl Parathion - Mice, by Routes
Other Than Oral 53
9 Acute Oral Toxicity of Methyl Parathion in Mammals
(LD50 Values) 56
10 Acute Toxicity of Methyl Parathion to Mammals by
Routes Other Than Oral (1050 and LC5Q Values) 57
11 Effect on Offspring of a Single Intraperitoneal
Injection of Methyl Parathion in Pregnant Rats
On Day 12 64
12 Effect on Offspring of a Single Intraperitoneal
Injection of Methyl Parathion in Pregnant
Mice on Day 10 65
13 Amounts of Methyl Parathion Absorbed by Men Working
i» ULV-Treated Fields 72
vii
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TABLES (Continued)
No. Page
14 Acute Toxicity to Fish 87
15 Common and Scientific Names of Fish Used in Con-
trolled Toxicity Tests With Methyl Parathion 88
16 Acute Toxicity - Aquatic Invertebrates 94
17 Methyl Parathion - Summary of Registered Uses by
Crops, Application Rates, and Rate and Time
Restrictions 125
18 Pest Insects and Mites Against Which Methyl Parathion
is Recommended (in alphabetical order by common
names) 129
19 Registered Uses of Methyl Parathion Emulsifiable
Liquid (4 Ib active ingredient per gallon) -
Crops and Other Uses, Pests, Dosage Rates and
Use Limitations 131
20 Registered Uses of Methyl Parathion Emulsifiable
Liquid (4 Ib active ingredient per gallon) -
Crops and Other Uses, Pests, Dosage Rates and
Use Limitations 137
21 Estimated Uses of Methyl Parathion in the U.S. by
Regions and Major Crops, 1972 148
22 Methyl Parathion Uses in California by Major Crops
and Other Uses, 1970-1973 151
23 Use of Methyl Parathion in California in 1973 by
Crops, Applications, Quantities, and Acres
Treated 152
24 Use of Methyl Parathion in California in 1973 by
Crops, Applications, Quantities, and Acres
Treated 154
25 Results of Methyl Parathion Applied to Cotton Pests . . . 164
26 Results of Methyl Parathion Applied to the Sorghum
Midge 167
viii
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TABLES (Continued)
No. Page
27 Results of Methyl Parathion Applied to the Sorghum
Greenbug 169
28 Results of Methyl Parathion Applied to the Wheat
Greenbug 171
29 Results of Methyl Parathion Applied to the Sunflower
Moth 172
ix
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PART I. SUMMARY
CONTENTS
Production and Use 2
Toxicity and Physiological Effects 3
Food Tolerances and Acceptable Intake 4
Environmental Effects .... 4
Specific Hazards of Use 6
Limitations in Available Scientific Data 6
Efficacy and Cost Effectiveness 7
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This section contains a summary of the "Initial Scientific and
Minieconomic Review" conducted on methyl parathion. The section
summarizes rather than interprets scientific data.
Production and Use
Methyl parathion (0,0-dimethyl 0-p_-nitrophenyl jphosphorothioate)
has a broad spectrum of effectiveness against insects and is effective
against some species of mites. It is registered and recommended for use
in the United States on a large number of crops, including important
field, forage and vegetable crops.
Three reactions are involved in the synthesis of methyl parathion:
P2S5 + 4CH3OH
S
2(CH30)2PSH
(CH30)2PSH + C12
S
II
>(CH30)2PC1 + HC1 + S
(1)
(2)
ONa
(CH30) PCI +
(CH30)
Methyl parat
+ NaCl
(3)
ion
An estimated 51 million pounds of this active ingredient were pro-
duced in the United States in 1972 by four manufacturers. Methyl para-
thion imports in 1972 were reported to be 1.1 million pounds; exports
for that year are estimated to have been 12.5 million pounds. Thus,
domestic usage of this active ingredient in 1972 is estimated to have
been about 40 million pounds.
Methyl parathion is commercially available in a number of liquid,
powder, and dust formulations. No granular or aerosol formulations,
however, are registered.
In recent years, practically all domestic methyl parathion usage
has been in agriculture; no significant use has been made by either the
industrial, commercial, governmental, or home and garden sectors. We
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estimate that, in 1972, about 33.5 million pounds (85% of the total
domestic usage) were used on cotton; 3.1 million pounds were used on
soybeans; the balance was used on other field crops, vegetables, and on
other crops, and for control of mosquito larvae.
It is estimated that about three-fourths of the total 1972 domestic
usage of methyl parathion was used in the South Central states. The
remaining one-fourth of the total methyl parathion volume was used, in
decreasing order of usage, in the Southeast, the Southwest, the North-
west, and in the North Central states. There were no significant uses
of methyl parathion in the Northeast in 1972.
Toxicity and Physiological Effects
Methyl parathion is a highly poisonous insecticide. Acute oral
toxicities (11)50 values) for methyl parathion in various mammalian spe-
cies cover a wide range: 11.1 mg/kg in male rats, 18.5 mg/kg in mice, 417
mg/kg in guinea pigs, and 1,270 mg/kg in rabbits. The acute toxicity
of methyl parathion to rats was found to be as follows:
Route of entry Measurement Value
Oral LD50 11.1-16.0 mg/kg
Intraperitoneal ^50 3.6 mg/kg
Dermal ^50 ^7 mg/kg
Inhalation LC50 * nr °'2 m8/^
LC50 4 hr 0.12 mg/j£
Published data on the effects of methyl, parathion in humans are
limited. No data were found to indicate the lethal dose of methyl para-
thion for man. Humans have been shown to tolerate oral doses of 20 mg/
day of methyl parathion (approximately 0.28 mg/kg/day) for 4 weeks
without any significant changes in plasma or RBC cholinesterase levels.
Methyl parathion and methyl paraoxon are readily absorbed through
the skin and from the stomach. Injected methyl parathion can be detected
in several organs and tissues, but is most concentrated in the liver and
lung. Demethylation is the principal detoxifying pathway for methyl
parathion. Excretion products of methyl parathion are dimethyl phos-
phoric acid, methyl phosphate, methyl phosphorothioate, dimethyl phos-
phorothioic acid, and phosphoric acid.
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A dosage of 30 ppm (approximately 1.5 mg/kg/day) of methyl parathion
in the feed of rats has been shown to reduce reproductive performance;
10 ppm (approximately 0.5 mg/kg/day) did not reduce reproductive perform-
ance. It has also been shown for quail that a daily intake of 60 ppm of
methyl parathion reduces the hatchability of their eggs.
The teratogenic effects of methyl parathion have been studied in
rats; no gross abnormalities were produced in the embryo or the young
when the mothers were injected with methyl parathion at dosages of 4 and
6 mg/kg of body weight. Another investigation did not indicate any mal-
formation of young rats when the dosage was raised to 15 mg/kg of body
weight. Lethality, suppression of growth, and some teratogenic effects
were produced in the young of mice when the injected dosage was raised
to 60 mg/kg.
No information was found on the possible oncogenic effects of
methyl parathion. No chromosomal aberrations were found in bone marrow
cells of mice that had been injected with 5, 10, and 20 mg/kg of body
weight of methyl parathion.
Occupational protection standards have recently become effective
which prohibit unprotected workers from entering treated fields until at
least 48 hr after application of methyl parathion.
Food Tolerances and Acceptable Intake
In the United States, tolerances for methyl parathion and parathion
are the same. The established tolerances apply to the combined total of
methyl parathion and parathion. Tolerances have been established for
about 100 raw agricultural commodities.
The acceptable daily intake (ADI) for methyl parathion has been
set at 0.001 mg/kg.
Environmental Effects
Methyl parathion is toxic to fish and wildlife; product labels
carry a warning that birds and other wildlife in treated areas may be
killed. Available data indicate that methyl parathion is considerably
less toxic to fish than parathion (the 48-hr TI^ for bluegill is 8,000
yg/liter for methyl parathion, 47 ug/liter for parathion), and that a
safety margin exists between the rate of methyl parathion application
necessary for mosquito control, and concentrations that would harm fish.
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Only a few studies of laboratory evaluations of the toxicity of
methyl parathion to wildlife have been reported, and these addressed
only the susceptibility of birds. Comparative dietary toxicity studies
of methyl parathion showed that Japanese quail (LC50 = 46 ppm) were more
susceptible than bobwhite quail (LCcg = 90 ppm), that both quail species
were more sensitive than the pheasant (LCcQ = 116 ppm), and that the
mallard duck (LC^Q = 682 ppm) was the least sensitive of the four species
tested.
Methyl parathion is reported to be highly toxic to bees (e.g., the
LDcQ by topical application to adult worker bees is 0.5 ug/g). The
order of toxicity of methyl parathion to this species is in the same
range as that of parathion.
Very little data have been published on the effects of methyl para-
thion on parasites and predators. Field experiences of many cotton
entomologists, however, indicate that methyl parathion, at commercial
use rates, is highly detrimental to wasps, as well as to other important
parasites and predators.
Methyl parathion has been shown to cause a significant increase in
the content of bacteria and actinomycetes in soil at dosages 200 times
higher than the concentrations produced by normal field application.
The pattern of toxicity of methyl parathion to aquatic organisms
appears to be similar to that of parathion. Methyl parathion is ex-
tremely toxic to aquatic insects, toxic to the lower aquatic fauna, and
relatively nontoxic to the lower aquatic flora.
Data on the degradation of methyl parathion in soils show that its
half-life is generally one-fourth to one-half that of parathion. The
half-life of methyl parathion, applied at 1 to 50 Ib/acre to four soil
types, ranged from 3 to 11 days.
Available data indicate' that the soil .degradation of methyl para-
thion is temperature-dependent.
No data were found on the fate of the initial degradation prod-
ucts of methyl parathion, especially p_-nitrophenol and amino-methyl
parathion, or on the effects of these degradation products on organisms
other than mammals and insects.
Available d#ta indicate that methyl parathion is considerably less
persistent in water than parathion. Methyl parathion is hydrolyzed con-
siderably faster than parathion. In aqueous solution, at pH 1 to 5,
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and 20°C, 50% of methyl parathion is hydrolyzed in 175 days (compared to
690 days for parathion). At 15°C in 1 N NaOH, 50% hydrolysis of methyl
parathion is completed in 32 min. Available data, however,, are insuffi-
cient for an evaluation of the extent of water contamination with methyl
parathion.
Insufficient data are available on the origin, presence and persis-
tence of methyl parathion residues in air. Thus, the magnitude or con-
sequence of this problem cannot be evaluated.
There is no evidence that methyl parathion is biomagnified in food
chains or food webs, even though some organisms, especially lower aquatic
organisms, concentrate methyl parathion to some degree.
Specific Hazards of Use
The only major potential hazards associated with the registered
uses of methyl parathion that have been documented by this review are
its acute toxic hazard to man and, to a much lesser degree, its acute
toxic hazard to many of the other higher organisms and to beneficial
insects.
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 of perti-
nent areas:
1. Comprehensive long-term studies of the toxicity of methyl parathion
in at least one species. (One multiple (3) generation reproduction
study of rats has been reported, but the highest dosage tested was
30 ppm in the feed. This should include carcinogenic data.)
2. The mutagenic effects of methyl parathion.
3. The physiological effects of the major degradation products of
methyl parathion.
4. The toxicity of methyl parathion to wildlife under field conditions.
5. The interactions between methyl parathion and lower terrestrial
organisms.
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6. The fate in the environment of the major degradation products of
methyl parathion, especially p_-nitrophenol and amino-methyl
parathion.
7. The fate and persistence of methyl parathion residues in water.
8. The origin, presence, persistence, and significance of methyl
parathion residues'in air.
Efficacy and Cost Effectiveness
The economic benefits of using methyl parathion have been determined
from field tests on the control of the bollworm, boll weevil and tobacco
budworm on cotton; the sorghum midge and greenbug on sorghum; the greenbug
on wheat; and the sunflower moth on sunflowers. However, the data is
incomplete and should be looked upon with caution.
Methyl parathion gives good control of the bollworm, boll weevil and
tobacco budworm. However, the increased resistance of the tobacco bud-
worm to this insecticide in Texas is requiring the use of greater amounts
and more frequent applications. Tests at College Station, Texas, have
shown a 50-fold increase in the 1^50 value of methyl parathion to the
tobacco budworm between 1964 and 1972; a fivefold increase has been
noted in the Rio Grande Valley (Texas) between 1968 and 1972. Increased
resistance of the bollworm has also been noted in Texas where the LDc0
value doubled between 1971 and 1972.
Methyl parathion effectively controls the sorghum midge. However,
early uniform planting of the sorghum has reduced the incidence of this
pest.
The sorghum greenbug is effectively controlled by methyl parathion.
However, under some conditions, the phytotoxicity of this insecticide to
sorghum can adversely affect yield.
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Methyl parathion has proven to be very effective for control of
greenbugs on wheat crops. Its use has resulted in significant yield
increases over untreated plots.
The sunflower moth, a significant pest attacking sunflower seeds,
is effectively controlled by methyl parathion; multiple applications at
the proper times increased yields substantially.
The ranges of economic benefit from the use of methyl parathion on
major crops are summarized as follows:
Economic benefit (loss) ($/acre)
Crop pest Lowest yield* Highest yield
Cotton (bollworm, boll (30.20) 653.20
weevil, and tobacco
budworm)
Sorghum (midge) (8.40) 68.30
Sorghum (greenbug) (13.70) 13.10
Wheat (greenbug) 10.60 19.10
Sunflower (sunflower moth) (2.60) 57.90
* Data in parentheses are negative values,
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PART II. INITIAL SCIENTIFIC REVIEW
SUBPART A. CHEMISTRY
CONTENTS
Page
Synthesis and Production Technology 11
Physical Properties 14
Composition and Formulation 18
Chemical Properties, Degradation Reactions and Decomposition
Processes 20
The Effect of Sunlight and Ultraviolet Radiation 21
Hydrolysis 21
The Effect of Heat 22
Oxidation 24
Reduction 24
Analytical Methods 25
Multi-Residue Methods 26
Association of Official Analytical Chemists Methods 26
Pesticide Analytical Manual 26
Residue Analysis Principles 30
AOAC Method (Official Final Action) 30
PAM Methods 30
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CONTENTS (Continued)
Page
Formulation Analysis Principles 32
AOAC Methods (Official Final Action) 32
Environmental Protection Agency Methods 33
Occurrence of Methyl Parathion Residues in Food and Feed
Commodities 35
Acceptable Daily Intake 36
Tolerances 38
References 42
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This section of the scientific review of methyl parathion con-
tains a review of available data on its chemistry and presence in foods,
Seven subject areas have been examined:
1. Synthesis and Production Technology,
2. Physical Properties,
3. Composition and Formulation,
4. Chemical Properties, Degradation Reactions and Decomposition
Processes,
5. Occurrence of Methyl Parathion Residues in Food and Feed
Commodities,
6. Acceptable Daily Intake,
7. Tolerances, and
The section summarizes rather than interprets scientific data reviewed.
Synthesis and Production Technology
The chemical production processes used for methyl parathion and
parathion manufacture are almost identical. The only difference is in
the alcohol (methanol or ethanol) used in the initial reaction (with
phosphorus pentasulfide). The production equipment can be used for
producing either of these compounds, and in most cases the same equip-
ment has been used for the manufacture of both products.
The following lists known manufacturers and production levels of
methyl parathion.
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Plant
capacity^/
(million Ib/year)
Manufacturer and
plant location
Monsanto Company, Anniston,
Alabama 50
Stauffer Chemical Company,
Mount Pleasant, Tennessee 30
Kerr-McGee Chemical Corpora-
tion, Hamilton, Mississippi^/ 9
Los Angeles, California 3
Velsicol Chemical Corporation,
Bayport, Texas 10
Total 102
Estimated 1972 methyl
parathion production
(million Ib) _
25
15
7
0.5
3.5
51.0
Source: MRI estimates.
a/ Plant capacity is stated for methyl parathion plus (ethyl) parathion.
b_/ The Kerr-McGee plant at Los Angeles discontinued production after
1972.
Three reactions are involved in the synthesis of methyl parathion;
S
4CH30H - > 2(CH30)2PSH + H2S (1)
S
II
(CH30)2PSH + C12
(CH30)2PC1 + HC1 + S
(2)
(CH30)2PC1
N02
Acetone>
NaCl
(3)
12
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In the first two reactions the intermediate dimethyl phosphorothiono-
chloridate is produced. This intermediate may be produced on site or
elsewhere, or can be purchased from another manufacturer.
One of the most detailed accounts of methyl parathion manufacture
is described in a 1953 U.S. patent (Schrader, 1953i/) . According to
Schrader, the exothermic third reaction is performed at 80 to 100°C.
However, in a patent by Dvornikoff et at. (1953) JL/ it is preferred to
operate at a much lower temperature of from -10 to +10°C. The reaction
is performed at atmospheric pressure and requires a reaction time of 5 hr
at 80 to 95°C, but about 18 hr if performed at 0°C.
The reaction is conducted in the liquid phase. One of various or-
ganic solvents may be present. An alcoholic medium is specified by
Dvornikoff et al. (1953). However, an inert solvent such as benzene or
chlorobenzene is preferred by Schrader (1953). Monsanto apparently em-
ploys acetone as the solvent.
Copper powder may be used as a catalyst or the reaction may simply
be conducted in a copper reaction vessel, thereby shortening reaction
time appreciably. A small amount of potassium bromide can be used as
an effective co-catalyst. Aliphatic amine catalysts were cited for use
in this reaction byToyetal. (1949) .2/ Concentrations of at least 0.25%
of materials such as triethyl amine, tributyl amine, N-ethyl morpholine
and hexamethylene tetramine may be used.
The reaction is carried out in a stirred, jacketed vessel. Although
the reaction is conducted at essentially atmospheric pressure, closed
vessels must be used because by-product gases are both toxic and odorous.
The yield of methyl parathion is 90% or higher. The reaction prod-
uct mixture may be pumped through a precoated filter to remove gummy im-
purities. The filtrate may then be separated into aqueous and oily
layers. The lower oily layer may then be washed with a dilute sodium
I/ Schrader, G. (to Farbenfabriken Bayer), U.S. Patent No. 2,624,745
(6 January 1953).
2_/ Dvornikoff, M. N., et al. (to Monsanto Chemical Company), U.S. Patent
No. 2,663,721 (22 December 1953).
3/ Toy, A. D. F. et al. (to Victor Chemical Works), U.S. Patent No.
2,471,464 (31 May 1949).
13
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carbonate, solution, then with water; it may then be steam distilled to
remove by-product trimethyl thiophosphate. After cooling and settling,
the organic layer can be dried by heating under vacuum to give the final
product.
Monsanto produces methyl parathion by batch processes in equipment
dedicated to methyl and ethyl parathion production. Two of the raw ma-
terials are produced on site and the rest are received by rail. A pro-
duction schematic is shown in Figure 1. Raw materials and by-products
from the manufacture of methyl parathion are summarized in Table 1.
Stauffer's method of producing methyl parathion is believed to be
similar to Monsanto's.
No information is available concerning production methods at the
Kerr-McGee methyl parathion plant. The plant at Hamilton produces
neither P2S5 nor the p_-nitrophenol.
Physical Properties
Chemical Name: 0,0-dimethyl 0-p_-nitrophenyl phosphorothioate
Common Name: Methyl parathion
Trade Names: Dalf, Folidol M, Metron, Nitrox 80, Partron M,
Tekwaisa, E 601, Metaphor, Folidol 80, Wofatox
Pesticide Class: Broad-spectrum nonsystemic insecticide; organo-
phosphate
Structural Formula; CHoO * S
CH30 N0 (Q/ N02
Empirical Formula: CgH^QO^ NPS
Molecular Weight: 263.23
Analysis: C, 36.50%; H, 3.83%; N, 5.32%; 0, 30.39%; P, 11.77%;
S, 12.18%.
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SO2
t
Flare
H2S
t
SO2
t
Incinerator
Reactor
Dialkyl
Ester
CI2-
•HCI-
Chlorinator
• Ch lor idothionate
NaOC6H4NO2-
Acetone
Parathion
Unit
I
Nad-
Na2CO3-
Partial
Recovery
Methyl
Parathion
Waste
Treatment
Plant
City
Sewer
Source: 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 Environmental Protection Agency, Contract No.
68-01-0142 (January 1972).
* •*
Figure 1. Production schematic for methyl parathion.
15
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Table 1. RAW MATERIALS AND BY-PRODUCTS IN THE MANUFACTURE OF
METHYL PARATHION
•. t ..-,,..
1.
2.
3.
4.
5.
6.
Material
P S
ci2
CH3OH
NaOC6H4N02
Acetone
Soda ash
Received
From
On-site
Louisiana
Louisiana
On-site
Southwest
Raw Materials
Received
By
Tote bins
Rail, tanks
Rail, tanks
Rail, tanks
. East; middle- Rail, tanks
west
Storage
Tote bins
Tank cars
Tank
Bulk
Remarks
Vented to pro-
duction sys-
tem
For waste
disposal
Reaction By-Products
1.
2.
3.
4.
Material
V
HC1
S
NaCl
Form
Gas
Gas
Amount produced
Qb/lb AI)
0.06 calcd.
0.12 calcd.
0.11 calcd.
0.20 calcd.
Other Process Wastes and
Material
Active Ingre-
Form
Aqueous
Amount produced
(lb/lb AI)
Disposition
Flared
Most re-
cycled
Incinerate
Biol. waste
treatment
Losses
Disposition
Remarks
S02 air pol-
lutant
Some to liquid
waste
S02 , some
w
Discharged to
city sewer
Remarks
Liquid waste < 1 ppm to
dient
Solvents
Other: Organo- Gas liquid
phosphates
p-nitrophenol
Source: Lawless, E. W., et al., op. cit. (1972).
treatment
Burned
Liquid waste
treatment
Liquid waste
treatment
city sewer
16
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Physical State and Melting Point;
(Collaborative International Pesticide Analytical Council (CIPAC) , 19701/)
Pure: White crystalline solid, m. p. 35 to 36°C
Technical: Light to brown liquid, crystallizing about 29°C
(Martin, 1971 1/)
Pure: White crystalline powder, m.p. 35 to 36°C
Technical: Light to dark tan liquid, crystallizing about 29°C
(Strecher, 19681/)
Pure: m.p. 37 to 38°C
(Monsanto A/ )
Technical: 80% solution in xylene, garlic-like odor, 18.3°C
(Stauffer,
Technical: 80% solution in xylene, brown liquid, crystallization
temperature 18° C
Boiling Point: Thermally unstable, cannot be heated to normal boil
ing point. Do not heat above 55°C (131°F) .
Vapor Pressure (pure): 0.97 x 10~5 mm Hg at 20°C
Specific Gravity; Pure: 1.358 at 20°C
Technical (80% in xylene) : 1.22 at 20°C
I/ Collaborative International Pesticide Analytical Council, "Analysis
of Technical and Formulated Pesticides," CIPAC Handbook, 1 (1970).
21 Martin, H., Pesticide Manual. British Crop Protection Council, Second
Edition (1971).
3/ Strecher, P. G., Ed., The Merck Index, Eighth Edition, Merck and
Company, Rahway, New Jersey (1968).
4/ Monsanto Company, Agricultural Division, "Parathion, Methyl Parathion,"
Technical Bulletin No. AG-lb, St. Louis, Missouri (undated).
5_/ Stauffer Chemical Company, Methyl Parathion Technical Bulletin
(October 1969).
17
-------
Density; Technical (80% in xylene): 10.2 Ib/gal at 20°C
25
Refractive Index (pure): HD = 1.5367
nj*5 = 1.5515
Viscosity (80% in xylene): 6 cp at 25°C
Solubility; Water at 25°C—55 to 60 ppm at 25°C. Slightly soluble
in light petroleum and mineral oils; soluble in most
other organic solvents; slightly soluble in lipids and
fats.
Flash Point (tag open cup): 46°C (80% solution in xylene)
Volatility (pure): 0.14 mg/m3
Composition and Formulation
The most common formulations of methyl parathion are emulsifiable
concentrates (2 to 7 Ib/gal) and dusts. Some suggested emulsifiable con-
centrates are presented in Table 2.
Stable field strength dusts can be prepared from stabilized concen-
trates made with attapulgite or nonswelling montmorillonite clay. In
addition, an extender of pyrophyllite or kaolin can be used in combina-
tion with treated calcium carbonate. Direct impregnation, using one of
the above combinations of diluents, produces equally stable field strength
dusts.
A 20% or 25% stabilized methyl parathion dust concentrate, suitable
for further letdown, can be formulated with the following composition:
Ingredients 20% (Ib) 25% (Ib)
Attapulgite or montmorillonite clay 74.75 68.5
(nonswelling)
Methyl parathion (stabilized) 25.25 31.5
Total 100.00 100.0
18
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Table 2. SUGGESTED FORMULATIONS FOR METHYL
PARATHION EMULSIFIABLE CONCENTRATES
Ingredients
Methyl parathion (80%)
Xylene
Emulsifier
% by Wt
2 Ib/gal
Lb/Gal
Methyl parathion (80%)
Xylene
Emulsifier
Methyl parathion (80%)
Xylene
Emulsifier
4 Ib/gal
57.05
37.95
5.00
100.00
6 Ib/gal
78.41
14.09
7.50
100.00
Methyl parathion (80%)
Xylene
Emulsifier
7 Ib/gal
87.90
4.10
8.00
100.00
Source: Monsanto Technical Bulletin No. AG-lb
a/ Equivalent to 2.0 Ib of 100% methyl parathion
Specific Gravity at 25/15.6°C. 0.9609
Solution Point, °C. -13
b/ Equivalent to 4.0 Ib of 100% methyl parathion
Specific Gravity at 25/15.6°C. 1.0517
Solution Point, °C. -0.5
£/ Equivalent to 6.0 Ib of 100% methyl parathion
Specific Gravity at 25/15.6°C. 1.1478
Solution Point, °C. +11
d/ Equivalent to 7 Ib of 100% methyl parathion
Specific Gravity at 25/15.6°C. 1.1945
Solution Point, °C. 14.5°
19
-------
Typical field strength dusts containing 1 to 5% stabilized methyl
parathion can be formulated with the following compositions (for approxi-
mately 100 Ib):
Ingredients .„.«.. Amount (Ib)
Attapulgite or montmorillonite clay
(nonswelling) 25
Pyrophyllite talc or kaolin clay 35
Calcium carbonate (treated) 35
Methyl parathion (stabilized) 1.31-6.31
Chemical Properties, Degradation Reactions and Decomposition Processes
The chemical reactions of methyl parathion and parathion are very
similar. However, much of the chemistry has been investigated using
the ethyl isomer, parathion.
Methyl parathion is a specific chemical compound, 0,0-dimethyl
0-p_-nitrophenyl phosphorothioate (Chemical Abstracts nomenclature).*
The biological effects of methyl parathion are intimately associated
with two other compounds, methyl paraoxon (0,0-dimethyl 0-p_-nitrophenyl
phosphate) and a thiolate isomer of methyl parathion (0,S-dimethyl 0-p_-
nitrophenyl phosphorothiolate). As indicated below, these compounds
are formed by oxidation and isomerization of methyl parathion.
S 0
II /^\ oxidation II
(CH30)2PO(( )>N02 > (CH30)2PO
Methyl parathion
Methyl paraoxon
isomerization
Thiolate isomer
Parathion is the corresponding ethyl ester, 0,0-diethyl 0-p_-nitro-
phenyl phosphorothioate.
20
-------
Compounds of this kind are toxic primarily because they react with
acetylcholinesterase. The toxicity of methyl parathion depends entirely
upon its oxidative conversion ±n_ vivo to methyl paraoxon. Methyl para-
thion is oxidized enzymically to methyl paraoxon, but can also be oxidized
to methyl paraoxon by the chemical action of atmospheric oxygen. The
atmospheric oxidation is accelerated by ultraviolet radiation.
The Effect of Sunlight and Ultraviolet Radiation - When methyl parathion
was exposed to both UV radiation and sunlight only methyl paraoxon was
identified (Koivistoinen and Merilainen, 1962I/).
Hydrolysis - Hydrolysis is perhaps the most important degradation reac-
tion of organic phosphorus insecticides, because hydrolysis virtually
destroys all insecticidal activity.
The extent of hydrolytic stability is, in general, related to the
electronic characteristics of the substituents attached to the phos-
phorus atom. Thus, the replacement of a phosphorus-bound oxygen atom
with a sulfur atom usually increases the resistance of the molecule to
hydrolysis. This fact probably accounts for the fact that the chemi-
cal structures of most commercial organophosphate insecticides contain
sulfur.
In methyl parathion (and in parathion), there are three potential
groups which may be hydrolyzed from the phosphorus portion of the mole-
cule. However, only one, the p_-nitrophenol group, is of practical sig-
nificance; the hydrolysis of the most labile group greatly increases the
hydrolytic stability of the remaining groups.
The rate of hydrolysis of methyl parathion is considerably faster
than that of parathion; at pH 1 to 5, 50% is hydrolyzed in 175 days at
20°C (compared to 690 days for parathion under the same conditions).
The rate of hydrolysis of methyl parathion in alkaline medium is even
faster; only 32 min are required for 50% hydrolysis in IN NaOH at 15°C
(Melnikov, 1971;1/ Lawless et al., 1973-*/).
I/ Koivistoinen, P., and M. Meril'ainenj "Paper Chromatographic Studies
on the Effect of Ultraviolet Light on Parathion and Its Deriva-
tives," Acta Agr. Scand.. 12:267-276 (1962).
2j Melnikov, N. N., Chemistry of Pesticides, Springer-Verlag, New York
(1971).
3/ Lawless, E. W., T. L. Ferguson, and A. F. Meiners of Midwest Research
Institute, ^Methods for the Disposal of Spilled and Unused Pesticides
(draft), for Environmental Protection Agency, Contract No. 68-01-0098
(1973).
21
-------
The Effec-t of Heat - Thermal isomerization has been demonstrated for
methyl parathion; 91% isomerization resulted within 6.5 hr at 150°C
(Metcalf and March, 1953I/). Only one decomposition product, the S-
methyl ester (thiolate isomer) was identified. (See Figure 2.)
Heating most insecticidal organophosphates above 200°C results in
decomposition. With methyl parathion, isomerization to the S-methyl
isomer is followed by the generation of dimethyl sulfide and sulfur
dioxide and a mixture of poly(aryl metaphosphates), which decompose to
a carbonaceous residue that is explosive (McPherson and Johnson, 1956=.').
Methyl parathion may also decompose at temperatures between 65 and 115°C.
However, the time for decomposition is measured in days rather than
hours (Dauterman, 197Is/).
According to the National Agricultural Chemicals Association (1968),ft/
methyl parathion may explode at 120°C. For an adequate safety margin,
methyl parathion should not be heated above 55°C. When heated to decom-
position, methyl parathion emits highly toxic fumes of nitrogen oxides,
phosphorus, and sulfur compounds (National Agricultural Chemicals Associ-
ation, 1968).
The hazards from fires involving organic phosphorus insecticides
have been investigated and it was concluded that most of the insecticide
is destroyed by decomposition before it can evaporate, and over 90% of
the evaporating insecticide is destroyed by the flames (Smith and
Ledbetter, 197l5/).
\j Metcalf, R. L., and R. B. March, "The Isomerization of Organic Thio-
phosphate Insecticides," J. Econ. Entomol.. 46:288-294 (April 1953).
2_/ McPherson, J. B., Jr., and G. A. Johnson, "Thermal Decomposition of
Some Phosphorothioate Insecticides," J. Agr. Food Chem., 4(1):42-
49 (January 1956).
3_/ Dauterman, W. C., "Biological and Nonbiological Modifications of
Organophosphorus Compounds," Bulletin of the World Health Organiza-
tion, 44(1-2-3):144 (1971).
4/ National Agricultural Chemicals Association, Safety Guide for Ware-
housing Parathions, Washington, D.C., 19 pages (1968).
5/ Smith, W. M., Jr., and J. 0. Ledbetter, "Hazards from Fires Involv-
ing Organophosphorus Insecticides," Amer. Ind. Hyg. Assoc. J.,
32(7):468-474 (July 1971).
22
-------
D
(CH^Ho
N0
Heat
CH«S
150°C, 6.5 hr
+ Unidentified products
ro
u>
Methyl parathion
S-methyl parathion
Heat
200 °C
V
(CH3)2S + S02 + Solid products
Adapted from: Metcalf, R. L., and R. B. March, op. cit. (1953); McPherson, J. B., Jr.,
and G. A. Johnson, op. cit. (1956).
Figure 2. Thermal isomerization of methyl parathion.
-------
Oxidation - Several chemical oxidizing agents are capable of replacing
the sulfur atom in parathion with an oxygen atom. Although no specific
references were located which described the oxidation of methyl para-
thion, it would be expected that the oxidative reactions of methyl para-
thion would be similar to those of parathion.
• •
Koivistoinen and Merilainen (1962) showed that when parathion was
exposed as a thin film, trace amounts of paraoxon were formed even in
the absence of light.
A recent publication (Gunther et al., 197o!/) pointed out that para-
thion can be rapidly and conveniently oxidized to paraoxon by means of
ozone (20 to 40% conversion).
21
Comma and Faust (1971)— noted that chlorine or potassium permanga-
nate would convert dilute solutions of parathion in water to paraoxon.
Reduction - Reducing agents (for example, metals in acid medium) convert
methyl parathion to the corresponding amino compound (Melnikov, 1971).
The product, 0,0-dimethyl 0-4-aminophenyl thiophosphate, is nontoxic to
animals and does not have an insecticidal effect.
I/ Gunther, F. A., D. E. Ott, and M. Ittig, "The Oxidation of Parathion
to Paraoxon. II. By Use of Ozone," Bull. Environ. Contam. Toxicol.,
5(l):87-94 (1970).
2_/ Comma, H. M., and S. D. Faust, "Chemical Oxidation of Organic Pesti-
cides in Aquatic Environments," Paper No. 48, 161st American Chemi-
cal Society Meeting, Los Angeles, California (29 March-12 April
1971).
24
-------
Analytical Methods
This subsection reviews methyl parathion 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, II,I/ (2) Official Methods of Analysis of the
Association of Official Analytical Chemists.I/ C3) Analytical Method's for
Pesticides and Plant Growth Regulators_.jL/
The Pesticide Analytical Manual - The "Pesticide Analytical Manual" (PAM),
published by the Food and Drug Administration, provides procedures 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 cf Official Analytical
Chemists - The Association of Official Analytical Chemists (AOAC) publishes
an authoritative methods manual published 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 reproducibility of the method by profes-
sional analysts.
When an AOAC method is adopted for the first time it is published as
"Official First Action." This designation serves notice that final adop-
tion 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.
I/ U.S. Department of Health, Education, and Welfare, Food and Drug
Administration, Pesticide Analytical Manual, 2 vols. (1971).
21 Association of Official Analytical Chemists, Official Methods of
Analysis of the Association of Official Analytical Chemists, 11th
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).
25
-------
Analytical Methods for Pesticides and Plant Growth Regulators, Volume VI,
Gas Chromatographic Analysis - Chapter 6 of this text (Zweig and Sherma,
1972) 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 rela-
tive retention times of various pesticides on various column materials,
and (7) a review of the sensitivity of various gas chromatographic systems.
Multi-Residue Methods -
Multi-residue methods for methyl parathion 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 ,i/ 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
"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.
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 ether) contains some chlorinated
pesticides and some phosphated pesticides. However, methyl parathion
and parathion (and diazinon) are obtained in a second eluate (15% ethyl
ether in petroleum ether). A third eluate (50% ethyl ether in petroleum
ether) 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
JL/ AOAC, op. cit., p. 475 (1970).
21 AOAC, op. cit., p. 484 (1970).
3_/ AOAC, op. cit., p. 487 (1970).
26
-------
are not capable of detecting and measuring all pesticides. Analytical
schemes used in the detection of methyl parathion are shown in Figures 3 and
4. The various parts of the schemes shown in Figures 3 and 4 are outlined
in detail in the PAM. (The numbers refer to the chemical numbering system
of PAM; the chapter numbers also refer to PAM.)
Methyl parathion is more than 80% recovered in the 15% ethyl ether in
petroleum ether fraction from the Florisil column. Over 80% recovery is
achieved from both fatty and nonfatty foods.
Relative retention times of methyl parathion are presented below for
various column packings; the corresponding response for various detectors
is also indicated.
Electron Capture Detector
Retention time Response
Column relative to aldrin (ng for 1/2 FSD*
packing (ratio) at 1 x 10"9 AFS**)
107. DC 200 on 0.68 2-3
Gas-Chrom Q
(or Anakrom Q)
15% QF-1, 1.42 2.5
10% DC 200 on
Gas-Chrom Q
Sulfur Detector
Retention time Response
Column relative to sulphenone (ug for 112 FSD*
packing (ratio) 64 ohms)
10% DC 200 on 0.60 2
Gas-Chrom Q
15% QF-1, 0.55 2
10% DC 200 on
Gas-Chrom Q
* FSD = Full scale deflection.
** AFS = Amps, full scale.
27
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Figure 3
GENERAL SCHEME FOR MULTIPLE RESIDUES *
Chlorinated (nonionic)
210
Organophosphates
230
See Scheme 162**
Sample Preparation
141
Guidelines for
Compositing
142
Extraction and
Cleanup
Chapter 2
I
Gas Chromatography
(quantitative)
Chapter 3
Thin Layer
Chromatography
(semi - quantitative)
Chapter 4
Determinative
Methods - other
Chapter 5
Confirmatory Tests
Chapter 6
1
Chlorinated (ionic)
220
Sec 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.
28
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Figure 4
ANALYTICAL SCHEME FOR CHLORINATED (NONIONIC) AND ORGANOPHOSPHATE RESIDUES*
Chlorinated (Noiiionic) 210
Orgaiiophosphatcs 230
Proximate Percentage Water
and Fat in Foods and Feeds 202
Fatty Foods
211 231
Non Fatly Foods
212 232
Florisil Column
211.15
Extraction of Fat
211.13
Acetonitrile
Partitioning
211.14
Extraction and
Partitioning
212.13
1
i
i
!
i
i
i
i
i
i
1
1
1 CO/- 1?1..~*_
1
1 I
2nd Florisil
Column
211. 16 a ""•---*.
__ J
....i ,
Acid-Celite
Column- ^^.
211. 16 b --'-""
& 2nd Florisil
Column
Gas Chromalography
Electron Capture and Thermionic
Dual Detection System 321
Cos Chromatography
Electron Capture Detector
311
' 2nd Florisil
Column
^.''~-~' 211.16 a
"^
MgO-C elite
^- -•""'" Column
211.16 c
X L ,
_ _.a N ^ ^
1
Thin Layer Chromatography
Chlorinated 410
Organophosphates 430
xx Alkaline
%Nj Hydrolysis
211.16 d
& MgO-Celite
1 Column
|~
1
I
i
i
I
__ J
1
I
i
_ j
* 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.
-------
Potassium Chloride Thermionic Detector
Retention time
Column relative to parathion Response
packing (ratio) (mg for 1/2 FSD*)
107. DC-200 on 0.7 2.5
Chromosorb W-HP
(or Gas Chrom Q)
15% QF-1 + 107o
DC 200 on Chromosorb 0.76 2
W-HP (or Gas Chrom Q)
* FSD = Full scale deflection.
** AFS - Amps, full scale.
The PAH does not provide response data for flame photometric
detectors. However, this type of detector is now widely used for the
analysis of organophosphate 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 manual and PAM (Vol. II) describe methods for the
specific analysis of parathion residues. The PAM methods are stated to be
applicable to methyl parathion, but no similar statement was found in
AOAC (1970). However, an examination of the AOAC methods reveals that they .
should be applicable to both parathion and methyl parathion. Zweig and Sherma±/
have provided a review of specific residue analytical methods for methyl
parathion.
AOAC Method (Official Final Action) - According to the AOAC method—' for
specific analysis of parathion (and, presumably, methyl parathion) residues,
parathion is extracted with benzene or 2-propanol-benzene, and the strip
solution is clarified. Parathion is brought into aqueous solution and
simultaneously reduced to its amine with zinc and hydrochloric acid. The
I/ Zweig and Sherma, op. cit.. p. 205 (1972).
2/ Zweig and Sherma, op. cit.. p. 445 (1972).
3f AOAC, op. cit.. p. 508 (1970).
30
-------
amine is dlazotized and coupled with N-(l-naphthyl)-ethylenediamine to form
a colored compound which is analyzed spectrophotometrically.
The practical working range for the Beckman DU spectrophotometer is
0 to 200 ug parathion.
The method has been employed for parathion residues in a wide variety
of fruits and vegetables.
PAM Methods - PAM (1967) lists three methods for specific residue analysis.
The first two methods have been "tested in varying degrees and are consid-:
ered reliable without further validation for the product applications
indicated." The third method has not been "thoroughly tested through
interlaboratory studies."
The First Method - This method refers to the PAM procedure for organo-
phosphate (PAM, 1971); This procedure is summarized in the "Multi-Residue
Methods" section.
The Second Method - This method refers to an AOAC procedure (AOAC,
1965,!/); a summary of an updated AOAC method is described in the preceding
section.
According to PAM (Volume II), the AOAC method is generally applic-
able to all products excluding fats and oils.
The sensitivity is 0.2 ppra.
Cole crops develop an interfering pink color, and blank values as
high as 1 ppm and over are not uncommon with some of these crops
(Rolston and Walton, 1963^/).
Aniline and some aniline analogues interfere. Methyl anthranilate,
which is found in grapes and citrus fruits, interferes. The amount of
methyl anthranilate and hence the extent of interference differs with
the maturity and variety of the fruit. (Taschenberg and Avens, I960— ).
I/ AOAC, op. cit., (1965).
2/ Rolston, L. H. and R. R. Walton, "Parathion Residues in Greens,"
J. Econ. Entomol.. 56:169-172 (1963).
3/ Taschenberg, E. F. and A. W. Avens, "Parathion and EPN Residue
Studies on Concord Grapes," J. Econ. Entomol., 53:441-445 (1960).
31
-------
Taschenberg and Avens used the procedure of Averell and Norris
(1948)-/ except that the benzene solution is repeatedly washed with
10% HCl to remove interference. Alternatively, methyl parathion can be
determined by difference: the anthranilate is determined before the
methyl parathion is reduced and then both compounds are measured together
after reduction. The difference in results represents the methyl parathion,
Decomposed leafy vegetables contain decomposition products v/hich
are not removed by the clean-up procedure and which yield false results.
(M. L. Dow, FDA, -private communication to PAM editors, October 1961).
The Third Method - The third method is a polarographic procedure which
can be used as a rapid scanning technique (Gajan, 1963.2/). The method has
been tested on apples and several vegetables. Parathion quantities of
less than 0.1 ppm have been determined. Methyl anthranilate does not
interfere. Methyl parathion, EPN, and PCNB give peaks sufficiently close
to the parathion peak as to interfere with the determination. Recent studies
by the author indicate that the procedure can be extended to fats and oils
except olive oil, where interferences have been encountered.
Formulation Analysis Principles -
Formulation analysis procedures for parathion are described in the
AOAC methods manual. The procedures should be applicable to methyl parathion
although this is not explicitly stated by AOAC. EPA's Technical Service
Division, Office of Pesticide Programs has provided additional formulation
analysis procedures.
AOAC Methods (Official Final Action) - The two AOAC methods are volumetric
(applicable to all forms of technical parathion) and colorimetric (applica-
ble to dusts and wettable powders).
I/ Averell, P. R. and M. V. Norris, "Estimation of Small Amounts of
0,0-diethyl 0-(p_-nitrophenyl)thiophosphate," Anal. Chem.. 20(8):
753-756 (August 1948).
2/ Gajan, R. J., "Applications of Oscillographic Polarography to the
Determination of Organophosphorus Pesticides, II. A Rapid
Screening Procedure for the Determination of Parathion in Some
Fruits and Vegetables," J. Assoc. Off. Agr. Chem.. 46(2):216-222
(1963).
32
-------
The volumetric method!/ involves a potentiometric titration of
the parathion amine (produced by reduction with zinc and hydrochloric
acid) with sodium nitrite. £-Nitrophenol in parathion is initially
removed by extraction (aqueous sodium carbonate) and determined by
ultraviolet spectrophotometry.
The colorimetric method-/ involves an extraction of parathion
with alcohol followed by a hydrolysis of parathion with potassium
hydroxide to form potassium £-nitrophenate which is determined by
ultraviolet spectrophotometry.
EPA Method - In addition to the AOAC formulation methods, the Technical
Service Division of EPA employs a high-pressure liquid chromatographic pro-
cedure and an infrared spectroscopic procedure for methyl parathion
analysis. The procedures are described as follows:—'
1. The High-Pressure Liquid Chromatographic Method -
a. Operating Conditions for Liquid Chromatograph - UV detector at
254 mm. Operating conditions must be determined for the
individual liquid chromatograph to achieve optimum sensitivity
and resolution.
b. Procedure -
1. Standard preparation - Weigh 0.1 g methyl parathion
standard into a 100 ml volumetric flask, dissolve, and
make to volume with methanol.
2. Sample preparation - Weigh a portion of sample equivalent
to 0.1 g methyl parathion into a glass-stoppered flask,
add 100 ml methanol, and shake well.
I/ AOAC, op. eit.. p. 114 (1970).
21 AOAC, op. cit.. p. 115 (1970).
_3/ Boynton, R. Warren, TSD, OPP, EPA, Personal Communication to
Dr. Alfred Meiners (September, 1974).
33
-------
c. Determination — Using a high-pressure liquid syringe,
alternately inject three 5 ^Lil portions each of standard and
sample solutions. Measure the peak area for each peak and
calculate the average for both standard and sample. Adjust-
ments in attenuation or amount injected may have to be made
to gove convenient size peaks.
d. Calculation -
. n ... (avg area sample) (^1 std) (ug/ul std) (purity of std) (100)
methyl parathion = (avg area 8tfd) (^ sample) (pg/JLll sample)
(This method was developed by Elmer H. Hayes of the Beltsville Chemistry
Laboratory, Technical Service Division, Chemical and Biological Investi-
gations . )
2. Infrared Spectroscopic Procedure -
a. Preparation of Standard - Weight 0.100 g standard methyl
parathion into a 10-ml volumetric flask. Dissolve and make
to volume with carbon disulfide. Add a small amount of
anhydrous sodium sulfate, shake, and allow to settle.
b. Preparation of Sample - Weigh a portion of sample equivalent
to 0.200 g of methyl parathion into a 250 to 300 ml glass-
stoppered Erlenmeyer flask. Add 100 ml acetone and shake on
mechanical shaker for 1 hr. If necessary, centrifuge to
clarify. Pipette 50 ml of the clear solution into a 125-ml
standard taper flask and evaporate on a rotary evaporator.
Add 5 ml carbon disulfide and evaporate again to remove all
traces of acetone. Transfer quantitatively with carbon
disulfide to a 10-ml volumetric flask, make to volume and add
a small amount of anhydrous sodium sulfate, shake, and allow
to settle.
c. IR Determination - Using the optimum quantitative settings for
the particular IR instrument being used, scan both the standard
and the sample solutions using the same 0.2-mm NaCl or KBr cell
in the sample beam. Compensate with carbon disulfide in a
matched 0.2-mm cell in the reference beam. For quantitative
results scan from about 7.0^i to 9.0^i (1425 cm"-*- to 1110 cm"1) .
For qualitative comparison run a full scan.
d. Calculation - Measure the absorbance of both standard and
sample using the peak at 8.10^ (1235 cm"1) and a baseline from
7.85 /a to 8.35yi (1275 cur1 to 1195 cm"1) . Calculate the per-
cent methyl parathion as follows:
% methyl parathion = (abs. sample) (wt. std.) (purity of std.) (1/10) (100)
(abs . std . ) (wt . sample) (50/100) (1/10)
34
-------
Occurrence of Methyl Parathion Residues in Food and Feed Commodities -
The Food and Drug Administration (FDA) 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
chemicals found in a high-consumption varied diet. The samples are
collected in retail markets and prepared for consumption before analysis.
The other program involves the examination of large numbers of samples,
obtained when lots are shipped in interstate commerce, to determine
compliance with established tolerances. These analyses are complimented
by observations 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 catego-
rized as "objective" samples. Objective samples are those collected
where there is no suspicion of excessive residues or misuse of the pest-
icide chemicals. All samples of imported foods and fish are categorized
as "objective" samples even though there may be reason to believe exces-
sive 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. A shop-
ping 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 similar 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 dilu-
tion factor. Each class in each sample is a "composite." The food items
and the proportion of each used in the study was developed in coopera-
tion 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 FDA
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 of the FDA analytical studies are tabulated for the
following food classes:
35
-------
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
The most recently available analytical data are presented in
Table 3, which lists the incidence and ranges of levels of methyl para-
thion detected in the various food classes. The omission of any food
class from the tables indicates that no residues were found.
The available data covers the years 1964 to 1969. Limited data is
available for the year 1970 (Corneliussen, 1972—) and a complete update
on pesticide residue data is expected in the forthcoming September 1974
issue of the Pesticide Monitoring Journal.
Acceptable Daily Intake
The acceptable daily intake (ADI) is defined as the daily intake
which, during an entire lifetime, appears to be without appreciable
risk on the basis of all known facts at the time of evaluation (Lu,
n I ^ '
1973^'). It is expressed in milligrams of the chemical per kilogram
of body weight (mg/kg).
JL/ Corneliussen, P. E., "Residues in Food and Feed: Pesticide Residues
in Total Diet Samples (VI)," Pest. Monit. J.. 5(4):313-329 (March
1972).
2/ Lu, F. C., "lexicological 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).
36
-------
Table 3. PERCENT DISTRIBUTION OF METHYL PARATHION RESIDUES
BY FISCAL YEAR IN DIFFERENT QUANTITATIVE RANGES
Range PPM
Percent Distribution of Samples
Domestic
1966-67 1968 1969 Total 1966-67
Imported
1968 1969
Total
Leaf and Stem Vegetables
No. Samples
5780
2251
1782
9813
None found
Trace-6.03
0.04-0.10
0.11-0.50
0.51-1.00
1.01-1.50
1.51-2.00
Above 2.00
95.69
1.31
0.96
1.73
0.22
0.06
-
-
91.60
3.78
2.18
2.09
0.31
0.04
-
-
90.85
3.87
2.19
2.97
0.06
-
-
0.06
93.88
2.34
1.47
2.04
0.21
0.05
-
. 0.01
35
8
19
62
100.00 100.00 100.00 100.00
No. Samples 5425
1758
Root Vegetables
1060 8243
165
None found
Trace- 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
99.79
0.09
0.07
0.01
0.01
-
-
^
99.43
0.28
0.11
0.11
0.06
-
-
^
98.58
0.85
0.38
0.19
-
-
-
—
99.56
0.23
0.12
0.06
0.02
-
-
"
98.78
1.21
-
•*
-
-
-
"
66
100.00
89
98.88
1,12
320
99.06
0.94
Adapted from 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 1 July 1963
to 30 June 1969," Pest. Monit. "j.. 5(2):73-212
(September 1971). " ~"
37
-------
For methyl parathion the ADI is 0.001 mg/kg. This level was set at
the 1968 Joint Meeting of the FAO Committee on Pesticides in Agriculture
and the WHO Expert Committee on Pesticide Residues (FAO/WHO, 1969I/). 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 methyl para-
thion has not been changed through 1971 (FAO/WHO, 197Zi/).
In making the evaluation, all available research on methyl parathion
concerning its biochemical effects, toxicology, and teratology was con-
sidered.
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. Toler-
ances for residues of methyl parathion have not been established per se,
but all residue tolerances established for parathion have been declared
applicable to methyl parathion. When both methyl parathion and parathion
residues are present, the tolerances apply to their combined total. A
summary of current tolerances applicable to methyl parathion is presented
in Table 4.
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.
JL/ FAO/WHO, Food and Agricultural Organization of the United Nations/
World Health Organization, "1968 Evaluations of Some Pesticide Resi-
dues in Food," The Monographs. Geneva (1969).
21 FAO/WHO, Food and Agricultural Organization of the United Nations/
World Health Organization, "Pesticide Residues in Food," Report of
the 1971 Joint FAO/WHO Meeting on Pesticide Residues, World Health
Organization Tech. Rept. Series No. 502. Geneva (1972).
38
-------
Table 4. SUMMARY OF U.S. TOLERANCES FOR METHYL PARATHION AND/OR PARATHION
ON RAW AGRICULTURAL COMMODITIES^'
ppm
0.1 (N)
25
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
0.75
1
1
1
1
1
1
Crop
Almonds
Alfalfa fresh
Alfalfa hay
Apples
Apricots
Artichokes
Avocados
Barley
Beans
Beets (with our without
tops)
Beet greens
Blackberries
Blueberries (huckleberries)
Boysenberries
Broccoli
Brussel sprouts
Cabbage
Carrots
Cauliflower
Celery
Cherries
Citrus fruits
Clover
Co Hards
Corn
Corn forage
Cottonseed
Cranberries
Cucumbers
Currants
Dates
Dewberries
Egg plants
1
1
0.1 (N)
1
1
1
1
1
1
1
1
1
1
1
1
1
0.2
1
1
1
1
1
1
1
1
1
1
1
1
0.1(1)(N
1
1
1
Endive (escarole)
Figs
Filberts
Carlic
Gooseberries
Grapes
Grass for forage
Guavas
Hops
Kale
Kohlrabi
Lettuce
Loganberries
Mangoes
Melons
Mustard greens
Mustard seed
Nectarines
Oats
Okra
Olives
Onions
Parsnips (with or
without tops)
Parsnip greens
Peaches
Pea forage
Peanuts
Pears
Peas
!) Pecans
Peppers
Pineapples
Plums (fresh prunes)
0.9(1)
1
1
1
1
0.2
1
1
1
1
0.5(1)
0.1(1)
0.1(1)
1
0.1
1
1
1
0.1(1)
0.1(1)
1
0.2
0.1(1)
1
1
1
1
1
0.1(1)
1
1
(N)
(N)
(N)
(N)
(N)
(N)
(N)
(N)
Potatoes
Pumpkins
Quinces
Radishes (with or with-
out tops)
Radish tops
Rape seed
Raspberries
Rice
Rutabagas (with or with-
out tops)
Rutabaga tops
Rye
Safflower seed
Sorghum
Soybean hay
Soybeans
Spinach
Squash
Strawberries
Sugar beets
Sugar cane
Summer squash
Sunflower seed
Sweet potatoes
Swiss chard
Tomatoes
Turnips (with or with-
out tops)
Turnip greens
Vetch
Walnuts
Wheat
Youngberries
Administrative guidelines - none.
Tolerances pending - all interim tolerances above.
(1) - Interim tolerances.
(N) - Negligible residue tolerances.
a/ Tolerances apply to combined methyl parathion and parathion if both are present.
Reprinted from Pesticide Chemical News Guide, by Food Chemical News, Inc., by permission of the publisher.
First publication 1 May 1974.
39
-------
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.
Rept. Series No. 228, Geneva (1962).
40
-------
The validity of the above criteria was reaffirmed at the 1966 FAO/
WHO meeting (FAO /WHO, 196?i/) .
The recommendations for methyl parathion tolerances established by
the 1968 Joint Meeting of the FAO and WHO (FAO /WHO, 1969) are:
Vegetables 1
Cole crops, cucurbits, fruit 0.2 ppm
Cottonseed oil (as processed) 0.005 ppm
I/ FAO/WHO, Food and Agricultural Organization of the United Nations/
World Health Organization, "Specifications for the Identity and
Purity of Food Additives and Their Toxicological Evaluation:
Some Emulsifiers and Stabilizers and Certain Other Substances,"
10th Report, Joint FAO/WHO Expert Committee on Food Additives,
World Health Organization Tech. Rept. Series No. 373, Geneva (1967)
41
-------
References
Association of Official Analytical Chemists, Official Methods of Analysis
of the Association of Official Analytical Chemists, 10th ed., Washington,
B.C. (1965).
Association of Official Analytical Chemists, Official Methods of Analysis
of the Association of Official Analytical Chemists, llth ed., Washington,
B.C. (1970).
Averell, P. R. and M. V. Norris, "Estimation of Small Amounts of 0,0-
diethyl 0-(p-nitrophenyl) thiophosphate," Anal. Chem., 20(8:753-756
(August 1948).
Boynton, R. Warren, U.S. Environmental Protection Agency, Office of
Pesticide Programs, Technical Services Division, Personal Communication
to Dr. Alfred Meiners (September 1974).
Collaborative International Pesticide Analytical Council, "Analysis of
Technical and Formulated Pesticides," CIPAC Handbook, 1 (1970).
Corneliussen, P. E., "Residues in Food and Feed: Pesticide Residues in
Total Diet Samples (VI)," Pest. Monit. J.s 5(4):313-329 (March 1972).
Dauterman, W. C., "Biological and Nonbiological Modifications of Organo-
phosphorus Compounds," Bulletin of the World Health Organization, 44
(1-2-3):144 (1971).
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 1 July 1963
to 30 June 1969," Pest. Monit. J., 5(2):73-212 (September 1971).
Dvornikoff, M. N., et al. (to Monsanto Chemical Company), U.S. Patent No.
2,663,721 (22 December 1953).
FAO/WHO, Food and Agricultural Organization of the United Nations/World
Health Organization, "Evaluation of the Toxicity of a Number of Anti-
microbials and Antioxidants," Sixth Report, Joint FAO/WHO Expert Com-
mittee on Food Additives, World Health Organization Tech. Rept. Series
No. 2285 Geneva (1962).
FAO/WHO, Food and Agricultural Organization of the United Nations/World
Health Organization, "Specifications for the Identity and Purity of
Food Additives and Their Toxicological Evaluation: Some Emulsifiers
and Stabilizers and Certain Other Substances," 10th Report, Joint FAO/
WHO Expert Committee on Food Additives, World Health Organization Tech.
Rept. Series No. 373, Geneva (1967).
42
-------
FAO/WHO, Food and Agricultural Organization of the United Nations/World
Health Organization, "1968 Evaluations of Some Pesticide Residues in
Food," The Monographs, Geneva (1969).
FAO/WHO, Food and Agricultural Organization of the United Nations/World
Health Organization, "Pesticide Residues in Food," Report of the 1971
Joint FAO/WHO Meeting on Pesticide Residues, World Health Organization
Tech. Rept. Series No. 502, Geneva (1972).
Gajan, R. J., "Applications of Oscillographic Polarography to the
Determination of Organophosphorus Pesticides, II. A Rapid Screening
Procedure for the Determination of Parathion in Some Fruits and Vege-
tables," J._Asjo^.pJf._^A£r_.Chem., 46(2) :216-222 (1963).
Comma, H. M., and S. D. Faust, "Chemical Oxidation of Organic Pesticides
in Aquatic Environments," Paper No. 48, 161st American Chemical Society
Meeting, Los Angeles, California (29 March-12 April 1971).
Gunther, F. A., D. E. Ott, and M. Ittig, "The Oxidation of Parathion to
Paraoxon. II. By Use of Ozone," Bull. Environ. Contam. Toxicol.,
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Koivistoinen, P., and M. Merilainen, "Paper Chromatographic Studies on
the Effect of Ultraviolet Light on Parathion and Its Derivatives,"
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43
-------
Lu, F. C., "Toxicological Evaluation of Food Additives and Pesticide
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1956).
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National Agricultural Chemicals Association, Safety Guide for Warehousing^
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Schrader, G. (to Farbenfabriken Bayer), U.S. Patent No. 2,624,745 (6
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Smith, W. M., Jr., and J. 0. Ledbetter, "Hazards from Fires Involving
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-------
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45
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SUBPART II. B. PHARMACOLOGY AND TOXICOLOGY
CONTENTS
Acute, Subacute and Chronic Toxicity 48
Toxicity to Laboratory Animals 48
Acute Oral Toxicity - Rats 48
Acute Toxicity - Rats, Routes Other Than Oral 48
Subacute and Chronic Oral Toxicity - Rats 48
Acute Oral Toxicity - Mice 48
Acute Toxicity - Mice, Routes Other Than Oral 52
Subacute and Chronic Oral Toxicity - Mice 52
Acute Oral Toxicity - Guinea Pigs 52
Acute Toxicity - Guinea Pigs, Routes Other Than Oral. ... 52
Subacute and Chronic Oral Toxicity - Guinea Pigs 52
Acute, Subacute and Chronic Toxicity - Dogs 52
Acute, Subacute and Chronic Toxicity - Cats 52
Acute, Subacute and Chronic Toxicity - Rabbits 54
Toxicity to Other Domestic Animals 54
Symptomatology and Pathology Associated with Mammals 54
Physiological and Pharmacological Aspects of Methyl
Parathion 54
Summary of Acute, Subacute and Chronic Toxicity 56
Metabolism of Methyl Parathion 57
Adsorption 57
Distribution 58
Biotransformation 58
Activation 58
Degradation 60
Tissue Residues 62
Summary ...... 62
Effects on Reproduction 62
46
-------
CONTENTS (Continued)
Rats 62
Avian Species 63
Teratogenic Effects 63
Mammals. •• 63
Behavioral Effects 66
Toxicity Studies With Tissue Culture 66
Mutagenic Effects 67
Oncogenic Effects 67
Effect on Humans 67
Acute and Subacute Toxicity 67
Symptoms of Methyl Parathion Poisoning 68
Dermal Effects 71
Inhalation Effects . 71
Occupational and Accidental Exposure Hazards 71
Field Operations 71
Manufacturing Operations 74
Accidents 75
Summary of Toxic Effects Other Than Acute, Subacute and Chronic
Toxicity 76
References 78
47
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In the following section, information is given on the acute,
subacute, and chronic toxicity of methyl parathion in laboratory
animals. The symptomatology and pathology associated with mammals
is discussed, and the physiological and pharmacological aspects of
exposure to methyl parathion have been summarized. Methyl para-
thion is also reviewed with regard to its absorption, distribution,
excretion, biotransformation, and residues in tissues. Information
has been sought on the toxicity of this organophosphate compound in
terms of its impact on reproduction, anomalies in the young, and
behavioral, mutagenic and oncogenic effects. The effects of methyl
parathion on humans has been reviewed relative to its acute, sub-
acute and dermal toxicity, inhalation effects, symptoms, possible
occupational hazards and accidental exposure hazards. The section
summarizes rather than interprets scientific data reviewed.
Acute, Subacute and Chronic Toxicity
Toxicity to Laboratory Animals -
Acute oral toxicity - rats - The oral LD^Q values calculated
from the results of several studies are shown in Table ,-. On the
average there appears to be relatively little difference between the
oral LD values for males (LD.-Q 11.07 mg/kg; range 6.0 to 16.0
mg/kg) and for females (LD^Q 15.95 mg/kg; range 4.5 to 24 mg/kg).
It appears that weanling rats (LDcQ 8.1 mg/kg are more susceptible
than mature animals.
Acute toxicity - rats, routes other than oral - Data are presented
in Table 6 for the toxicity of methyl parathion by intraperitoneal,
dermal and inhalation rates. With the few values that were found that
order of sensitivity is: inhalation (LC^o 1 hr - 0.2 mg/liter; LC5Q
l
4 hr - 0.12 mg/liter); intraperitoneal (LD^Q 3.55 mg/kg); and derma
exposure (LD50 67 mg/kg) .
Subacute and chronic oral toxicity - rats - Data on the subacute
and chronic oral toxicity in rats were not found in the literature.
Acute oral toxicity - mice - The acute oral toxicity information
that was found for methyl parathion .in mice is shown in Table 7.
Most of the information has been published in recent years. The
average LD^Q values for male-female groups of mice is 18.5 mg/kg.
Most of the LDcn values are grouped around 17 mg/kg.
48
-------
Table 5. ACUTE ORAL TOKICITY - RATS
Measurement (mg/kg*
unless otherwise Male Weanling
_ noted) _ Male Female female male Reference
Oral LD50 9.7 4.5 — — a/
Oral LD50 12-16 -- -- -- b/
Oral LD50 14 24 -- — c.d/
Oral LD5Q — -- 24.5 -- I/
Oral LDso -- 7,0 -- — I/
Oral LDjQ 5.8 -- -- 3.5 e.h/
Oral LD5Q — 9.7-14.8 — -- il
Oral LD5Q 6.0 — — — j/
Oral LD50 14.0 24.0 — — k/
Oral LD5Q — — 17.2 -- II
Oral LD50 — — 14.0 — m/
Oral LD50 14.0 24.0 — -- n/
Oral LD — -- -- 12.7 o/
X LD 11.07 15.95 18.6 8.1
* Body weight.
a/ DuBois, K. P., "The Toxicity of Organophosphorus Compounds to
Mammals," Bulletin of the World Health Organization. 44:
233-240 (1971).
b/ Edson, E. F., D. M. Sanderson, and D. N. Noakes, "Acute Toxicity
Data for Pesticides," World Review of Pest Control. 4:36-41
(1965).
c/ Gaines, T. B., "The Acute Toxicity of Pesticides," Toxicol.
Appl. Pharmacol.. 14:515-534 (1969).
d_/ Gaines, T.B., "The Acute Toxicity of Pesticides to Rats,"
Toxicol. Appl. Parmacol.. 2:88-99 (1960).
e/ Miyamoto, J., "Mechanism of Low Toxicity of Sumithion Toward
Mammals," Residue Rev.. 25:251-264 (1969).
gj OuBois, 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. Hed..
129:699-702 (1968).
g_/ Brodeur, J., and K. P. DuBois, "Comparison of Acute Toxicity of
Anticholinesterase Insecticides to Weanling and Adult Male
Rats," Proc. Soc. Exp. Biol. Med.. 114(2):509-511 (1963).
h/ Kimmerle, G., and D. Lorke, "Toxicology of Insecticidal Organo-
phosphates." Pflanz-Nachs. Bayer. 21:111-142 (1968).
i/ Deichmann, W. B., W. Pugliese, and J. Cassidy, "Effects of
Dimethyl and Diethyl Paranitrophenyl Thiophosphate on
Experimental Animals," AHA Arch. Ind. flyg. Occup. Med.. 5:44-51
(1952).
j/ Krueger, H. R., and J. E. Casida, "Toxicity of 15 Organophosphorus
Insecticides to Several Insect Species and to Rats," J. Econ.
Entomol.. 50(3) :356-359 (1957).
k/ Wills, H., "To Coulson, F., Division of Pharmacology, Albany
Medical College, Albany, New York," Unpublished report, quoted
in "1968 Evaluation of Some Pesticide Residues in Food," The
Monographs. Food and Agriculture Organization of the United
Nations and the World Health Organization, Geneva (1969).
\J Hagan, E. C., personal communication, cited in Williams et al.
(1959) .
ml Servintuna, C., "The Acute Toxicity of Insecticides at Oral and
Dermal Application." Bitki Koruma Bulteni. 3(4):275-284 (1963).
n/ Hayes, W. J., Jr., Clinical Handbook on Economic Poisons;
Emergency Information for Treating Poisoning. U.S. Department of
Health, Education, andWelfare Service, Communicable Disease
Center, Atlanta, Georgia, p. 13 (1963>.
o/ DuBois, K. P., M. Mazur, and K. W. Cormman, "Toxicity and Anti-
cholinesterase Action of p-Nitrophenyl Dimethyl Thionophosphate,"
Fed. Proc.. 9:269(1950).
49
-------
Table 6. ACUTE TOXICITY RATS - ROUTES OTHER THAN ORAL
Measurement (mg/kg*
unless otherwise Male
noted) Male Female female Reference
IP - LD5o -- — 3.5 a/
IP - LD5o — -- 3.6 b/
D - LD50 67 -- — £/
D - LD50 67 67 — i^e/
D - LD50 — — 6? i/
D - LD50 67 67 — £/
IN - LC50 (mg/j£) 1 hr 0.2 — — W
IN - LC50 (mg/jO 4 hr 0.12 — — h/
IP = Intraperitoneal.
D = Dermal.
IN = Inhalation.
* Body weight.
a/ DuBois, K. P., and J. M. Coon, "Toxicology of Organic Phosphorus-
Containing Insecticides to Mammals," AMA. Arch. Ind. Hyg. Occup. Med..
6:9-13 (1952).
b/ DuBois et al., op. cit. (1950).
£/ Edson et al., ^>p. cit. (1965).
d/ Gaines, op. cit. (1969).
e/ Gaines, op. cit. (1960).
£7 Servintuna, op. cit. (1963).
&/ Hayes, op. cit. (1963).
h/ Kimmerle and Lorke, op. cit. (1968).
50
-------
Table 7- ACUTE ORAL TOXICITY - MICE
Acute Oral LD_0 (mg/kg body weight)
Male
Male Female female Reference
£./
y
£/
f/
a/ Rosival, L., F. V. Selecky, and L. Vbrovsky, "Acute Experimental
Poisoning With Organophosphorus Insecticides," Bratislav.
Lekarske Listy, 38:151-160 (1958).
b/ Wills, op. cit. (1969).
£/ Ikeda, Y., "Report to the Japan Academy of Sciences," (1962),
quoted in "1968 Evaluations of Some Pesticide Residues in Food,"
The Monographs, Food and Agriculture Organization of the
United Nations and the World Health Organization, Geneva (1969).
d/ Suzuki, S., "Fenitrothion (Sumithion)," Noyaku Seisan Giiutsu. 22:
57-69 (1970).
e/ Miyamoto, op. cit. (1969).
if DuBois, op. cit. (1971).
£/ Does not include the value reported by Wills (1969).
51
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Acute 'toxicity - mice, routes other than oral - There was little
difference between the average LD^Q values by the intravenous (average
LDijQ 9.8 mg/kg), intraperitoneal (average LD^g 12.4 mg/kg), and sub-
cutaneous routes (LD50 18.0 mg/kg) reported as shown in Table 8 . All
the above values were for male-female groups. There appears to be very
little difference in toxicity of methyl parathion for mice with regard
to the route of administration.
Subacute and chronic oral toxicity - mice - No information was
available on either the subacute or chronic oral toxicities of methyl
parathion to mice from the available literature.
Acute oral toxicity - guinea pigs - The acute oral toxicity of
methyl parathion to the guinea pig has been reported to be 417 mg/kg
body weight (Miyamoto, 1969). This value is the highest level of
methyl parathion toxicity that was found for any mammalian species.
Acute toxicity - guinea pigs, routes other than oral - Miyamoto
(1969) reports an intravenous LDcQ of 50 mg/kg of methyl parathion for
the guinea pig.
Subacute and chronic oral toxicity - guinea pigs - No information
was found concerning the subacute or chronic oral toxicity of methyl
parathion to guinea pigs.
Acute, subacute and chronic toxicity - dogs - An unreferenced short-
term study has been reported (Anon., FAO/WHO, 1969-i') for the exposure
of dogs to methyl parathion. The feeding study was carried out for 12
weeks. In early test groups there were two dogs, and four dogs were
used for controls. The dieting levels were 5, 20, and 50 ppm. The only
information that was given was relative to RBC and plasma cholinesterase
activity. In the higher doses (20 and 50 ppm) the RBC cholinesterase
was depressed significantly, soon after the commencement of the test
diet. The maximum depression occurred at the 12th week. The animal re-
covered within 4 to 8 weeks after withdrawal of the insecticide. There
was a significant depression of the plasma cholinesterase activity for
the animals at the 50-ppm methyl parathion level. There were no signi-
ficant depression of plasma cholinesterase activity at the 5-ppm level
and depression was questionable at the 20-ppm level.
Acute, subacute and chronic toxicity - cats - No toxicity infor-
mation for cats for methyl parathion was found in the literature.
_!/ Anon., Food and Agriculture Organization of the United Nations and
the World Health Organization, "1968 Evaluations of Some Pesticide
Residues in Food," The Monographs, Geneva (1969).
52
-------
Table 8- TOXICITY OF METHYL PARATHION - MICE, BY ROUTES
OTHER THAN ORAL
LD5Q (mg/kg)
Route
IV
Male
Female
Male
female
Reference
a/
£/
b/
IP
SC
11.0
18.5
8.6
10.0
12.4 Average
18.0
£/
£/
d/
a/
IV = Intravenous injection.
IP = Intraperitoneal injection.
SC = Subcutaneous injection.
a/ Rosival et al., op. cit. (1958).
b/ Miyamoto, op. cit. (1969).
£/ Benke, G. M., K. L. Cheever, F. E. Mirer, and S. D. Murphy,
"Comparative Toxicity Anticholinesterase Action and Metabolism
of Methyl Parathion in Sunfish and Mice," Toxicol. Appl.
Pharmacol., 28:97-109 (1974).
d/ Dorough, H. W., "Effect of Temik® on Methyl Parathion Toxicity to
Mice," Progress Report, Texas A&M University No. 2771:1-6 (May
1970).
53
-------
Acute, subacute and chronic toxicity - rabbits - Wills (1969)
has reported that the oral LD^Q value in rabbits is 420 mg/kg; the
dosage was given in oil. In the undiluted form the LD5Q value was
1,270 mg/kg.
Toxicity to Other Domestic Animals - No references to the toxicity of
methyl parathion to other domestic animals"were found in the literature.
Symptomatology and Pathology Associated with Mammals - Because rela-
tively few studies have been conducted with methyl parathion, there
are few descriptions of symptoms which follow ingestion, absorption,
or inhalation of an acute dose.
Generally, the symptoms may be described as those characteristic
of poisonings with materials belonging to the organic-phosphorus
class of insecticides: restlessness, muscular twitchings, miosis,
defecation, urination, lacrimation, incoordination, prostration,
generalized muscular fibrillation, convulsions and death.
In the rabbit, methyl parathion does not appear to produce any con-
sistent gross pathological changes, and the signs of poisoning take longer
to appear in the rabbit than in guinea pigs and rats. Symptoms take
longer to appear in the guinea pig than in the rat (Deichmann et al.,
1952).
Observation of dogs poisoned with methyl parathion suggest that
after receiving an acute dose the sequence of events in the dog may be
as follows: moderate tremors and salivation, followed by pronounced
tremor, nausea, and dyspnea, and followed by very pronounced tremor,
convulsions, prostration, vomiting, unconsciousness, and eventually
death (Vandekar et al., 1965-1/).
Physiological and Pharmacological Aspects of Methyl Parathion - Methyl
parathion and parathion are biologically similar and they both metabo-
lize to oxygen analogs--paraoxon and methyl paraoxon (Augustinsson and
Jonsson, 1957—'). Methyl parathion is a cholinesterase inhibitor
\J Vandekar, M., B. Svetlicic, and T. Fajdetic, "The ED5Q Value as
Opposed to LD^Q Value in Acute Toxicity of Some Anticholines-
terases," WHO/Vector Control/163.65 (1965).
2/ Augustinsson, K. B., and G. Jonsson, Acta Chem. Scand., 11:375
(1957), quoted in "1968 Evaluations of Some Pesticide Residues
in Food," The Monographs, Food and Agriculture Organization of
the United Nations and the World Health Organization, Geneva
(1969).
54
-------
(Williams et al., 19591/) and is weaker in this capacity than parathion
(DuBois and Coon, 1952). Also, the analog methyl paraoxon is weaker
than ethyl paraoxon (Davidson, 1955J?/)'
Ethyl and methyl parathion are similar in their physiological and
pharmacological activity of cholinesterase inhibition. The following
general discussion on the mechanism of action of acetylcholinesterase
inhibitions is based on Hamblin^and Golz (1955).!.'
Acetylcholine, a neurotransmiter, is needed for impulse trans-
mission and this need is met by the action of the enzyme choline
acetylase. The hydrolysis of acetylcholine to choline and acetic
acid is accomplished by another enzyme, acetylcholinesterase (AChE).
There are a number of cholinesterases, the more prominent being true
and pseudocholinesterase. The former is found in nerve and muscle tissue
and in the erythrocytes. Pseudocholinesterase is found in the pancreas
and salivary glands and other tissues. The letter enzyme hydrolyzes ace-
tylcholine slowly.
The plasma cholinesterase is usually a mixture of true and pseudo
forms. The concentration varies widely from individual to individual
and plasma contains mostly pseudocholinesterase.
The absorption of parathion, an inhibitor of pseudocholinesterase
brings about the accumulation of sympathetic postganglionic fibers, in
sympathetic ganglia, and in the central nervous system, as well as at
the myoneural junctions of muscle.
The only cumulative aspect of parathion that is suggested is that
the inhibition is not reversible and acetylcholine recovery period is
contingent upon the death of the red cell. Repeated doses of parathion
will produce steadily decreasing levels of enzyme activity.
JL/ Williams, M. W., H. N. Fuyat, and 0. G. Fitzhugh, "The Subacute
Toxicity of Four Organic Phosphates to Dogs," Toxicol. Appl.
Pharmacol., 1:1-7 (1959).
2J Davidson, A. N., "Return to Cholinesterase Activity in the Rat
After Inhibition of Organophosphorus Compounds. II. A Com-
positive Study of True and Pseudo Cholinesterase," Biochem. J.
60:339-346 (1955).
3/ Hamblin, D. 0., and H. H. Golz, "Parathion Poisoning, A Brief
Review," Ind. Med. Surg.. 24(22):65-72 (1955).
55
-------
In the diagnosis of parathion poisoning, the RBC cholinesterase
level is the more important clinical measurement. The excretion of
p-nitrophenol is indicative of p exposure. Plasma cholinesterase is
more nonspecific and it has no functional relationship with the acti-
vity of the nervous system. A presumptive diagnosis of poisoning is
assumed when the plasma and RBC cholinesterase activity is depressed
by 25%.
In acute poisoning, manifestations usually occur only after more
than 50% of the plasma cholinesterase is inhibited. After an acute
poisoning it takes about 4 weeks for plasma cholinesterase and about
5 weeks for RBC cholinesterase to return to normal.
Summary of Acute, Subacute and ChronicTpxicity - Methyl parathion is
a highly poisonous insecticide. Its principal physiological action is
to inhibit the cholinesterases. The acute oral toxicity in mammals is
summarized in-the following table;
Table 9. ACUTE ORAL TOXICITY OF METHYL PARATHION IN
MAMMALS (LD5Q Values)
Rats
Mice
Guinea pigs
Rabbits
Male
(rag/kg)
11.07 (7)5/
9.7
Female
(mg/ltg)
15.95 0
4.5
Male and female
6)a/
IQ c o^a/
lo . j \/ )=J
417V
1,270£/
aj Average values ( ) number.
b_/ Sex was not stated.
£/ Not carried in a solvent; sex was not given.
d/ Given in oil; sex was not given.
It is rather striking that the LDijQ values for guinea pigs and
rabbits are high compared to rats and mice. The toxicity of methyl
parathion by other routes of administration, other than oral, for
mammals is shown in Table 10.
56
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Table 10. ACUTE TOXICITY OF METHYL PARATHION TO MAMMALS
BY ROUTES OTHER THAN ORAL (LDcQ and LC5Q Values)
Rats
Mice
Guinea pigs
Intra-
venous
(mg/kg)
9.8
50.0
Intra-
peritoneal
(mg/kg)
3.5
12.4
~ ""
Sub-
cutaneous
(mg/kg)
„
18.0
™ ^
Dermal
(mg/kg)
67
--
"" ""
Inhala-
tion
(mg/4)
0>2a/
0.12-^
a/ One-hour exposure.
b/ Four-hour exposure.
No subacute or chronic toxicity information was found for rats,
mice, guinea pigs, cats or rabbits. There was one paper that de-
scribed a 12-week feeding study with methyl parathion in dogs. It
was reported that the RBC cholinesterase was significantly depressed
at 20 and 50 ppm. The plasma cholinesterase was significantly de-
pressed at 50 ppm.
No information was found on the toxicity of methyl parathion in
dome s t ic animaIs.
The symptoms of methyl parathion poisoning in mammals are quite
similar to other organic-phosphorus compounds. The progression in-
cludes restlessness, tremors, miosis, loss of coordination, nausea, vom-
iting, muscle fibrillation, convulsions and death..
The physiological and pharmacological aspects of methyl parathion
toxicity center around the inhibitory effect on cholinesterases.
Metabolism of Methyl Parathion
Adsorption - A report by Nemec et al. (1968i') stated that two entomol-
ogists entered a field that had been spraved 2 hr earlier with 2 Ib/acre
of methyl parathion. They apparently adsorbed 2 to 10 mg of methyl para-
thion and had a 40% inhibition of red cell acetylcholinesterase.
I/ Nemec, S. J., P. L. Adkisson, and H. W. Dorough, "Methyl Parathion
Adsorbed on the Skin and Blood Cholinesterase Levels of Persons
Checking Cotton Treated With Ultra-Low-Volume Sprays," J. Econ.
Entomol.. 61(6):1740-1742 (1968).
57
-------
Fujinami (1963)—' demonstrated absorption and cholinesterase inhibi-
tion in rats, mice and guinea pigs treated with methyl parathion and
methyl paraoxon.
2/
Distribution - Miyamoto (1964)- studied the distribution of methyl
parathion after intravenous administration to rats and guinea pigs.
lAing and liver were found to be richest in methyl paraoxon. Orally
administered methyl parathion inhibited brain and blood cholines-
terase in rats, mice and guinea pigs within 1 hr (Fujinami, 1963).
Mice treated with 17 mg/kg of radioactive (^P) methyl parathion
excreted the following compounds within 24 hr after dosage: dimethyl
phosphoric acid, 31.9% (percent of radioactivity in the urine); methyl
phosphate, 23.1%; methyl phosphorothioate, 18.8%; dimethyl phosphoro-
thioic acid, 12.9%; phosphoric acid, 5.8%; unknown products, 3.1%;
phosphate, 2.4%; and methyl phosphoric acid, 2.0% (Hollingworth et al.,
19671/).
B iotrans formation -
4/
Activation - Metcalf and March (1953)— demonstrated that pure
methyl parathion did not inhibit fly brain acetylcholinesterase unless
it was converted to the oxygen analog by other tissues. Aldridge
(1954)57 reported that methyl parathion inhibited several esterases be-
sides acetylcholinesterase. Inhibition required conversion to the
oxygen analog. The inhibition and reversal rate varied widely with
different enzymes in the same species of animal.
I/ Fujinami, A., "Studies on the Mode of Action of Organophosphorus
Compounds. Part II. Inhibition of Mammalian Cholinesterase in
vivo Following the Administration of Sumithion and Methyl Para-
thion," A£r._jJi£l^_Chei1._, 27(l):669-676 (1963).
2j Miyamoto, J., "Studies on the Mode of Action of Organophosphorus
Compounds. Part III. Activation and Degradation of Sumithion
and Methyl Parathion in Mammals in vivo," Agr. Biol. Chem.,
28(7):411-421 (1964).
3/ Ifollingworth, R. M., R. L. Metcalf, and T. R. Fukuto, "The Selec-
tivity of Sumithion Compared With Methyl Parathion. Metabolism
in the White Mouse," J. Agr. Food Chem.. 15(2):242-249 (1967).
4/ Metcalf, R. L., and R. B. March, "Further Studies on the Mode of
Action of Organic Thionophosphate Insecticides," Ann. Entomol.
Soc. Am., 46:63-74 (1953).
51 Aldridge, W. N., "Anticholinesterases," Chemistry and Industry,
pp. 473-476 (1954).
58
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Dahm et al. (1962)i/ compared the activation of methyl parathion
by rat liver microsomal preparations in the presence of NADI^, magne-
sium ion and nicotinamide. Activation of methyl parathion could be
prevented by pretreatment with piperonyl butoxide, sulfoxide, sesa-
mex, testosterone propionate, androstanolone, estradiol, estrone and
SKF-525A. Brindley and Dahm (1964)i/ reported that rat liver micro-
somes, NADH2 and borate buffer at pH 7.7 at room temperature converted
methyl parthion to methyl paraoxon. Vardanis and Crawford (1964)—
found that the supernatant fraction of mouse liver converted methyl
parathion to methyl paraoxon. Johnsen and Dahm (1966)—' studied the
activation of methyl parathion by liver microsomes from eight species.
The results of their studies are summarized as follows:
Liver microsomal Methyl parathion
protein nitrogen activation
(pg/100 mg) (-log 150)
Species Male Female Male Female
Cattle 425 311 6.89 6.10
Chickens 223 333 5.34 6.17
Ducks 212 321 6.68 7.07
Guinea pigs 211 266 5.52 5.20
Hogs 290 266 5.36 5.66
Mice 288 353 6.64 6.77
Rats 284 225 7.01 5.68
Sheep 349 343 5.73 4.50
I/ Dahm, P. A., B. E. Kopecky, and C. B. Walker, "Activation of Or-
ganophosphorus Insecticides by Rat Liver Microsomes," Toxicol.
Appl. Pharmacol.. 4:683-696 (1962).
2/ Brindley, W. A., and P. A. Dahm, "Identification of the in vitro
Anticholinesterase Metabolite of Methyl Parathion," J. Econ.
Entomol., 57:47-49 (1964).
3_/ Vardanis, A., and L. G. Crawford, "Comparative Metabolism of 0,0-
Dimethyl 0-p-nitrophenyl Phosphorothioate (Methyl Parathion)
and 0,0-Dimethyl 0-(3-Methyl-4-Nitrophenyl) Phosphorothioate
(Sumithion)." J. Econ. Entomol., 57:136-139 (1964).
4/ Johnsen, R. E., and P. A. Dahm, "Activation and Degradation Effici-
encies of Liver Microsomes From Eight Vertebrate Species, Using
Organophosphates as Substrates," J. Econ. Entomol., 59(4):1437-
1442 (1966).
59
-------
Cheymol and Goyer (1966)i/ found the sulfur analog much less toxic
to true and pseudocholinesterase.
Degradation (detoxification) - Miyamoto (1964) reported that
intravenous methyl parathion in rats and guinea pigs was detoxified
to desmethyl compounds and dimethyIphosphorothioic acid in the liver
and kidney. Mendoza and Hatina (1970)—' extracted liver esterases
from male rhesus monkeys, chickens, turkeys, steers, barrows and sheep.
Steer esterases were slighly inhibited by methyl parathion but sheep
esterases were not inhibited. All others were strongly inhibited by
methyl parathion. Hollingworth et al. (1967) offered the following
pathways for the metabolism of methyl parathion. The broken arrows
indicate hypothetical pathways.
HO^
-------
Johnsen and Dahm (1966) also studied the degradation of methyl
paraoxon by liver microsomes from eight animal species. Results of
their studies are summarized as follows:
Activation (-log I50)
Species Male Female
Cattle 7.44 7.43
Chickens 7.36 7.36
Ducks 7.33 7.22
Guinea pigs 6.96 6.91
Hogs 7.32 7.16
Mice 7.15 7.10
Rats 7.14 7.37
Sheep 7.23 6.62
Miyamoto et al. (1968)!/ studied the metabolism of methyl parathion
by microsomes from rat, mouse and guinea pig liver. All required
NADH_ or NADPEL to convert methyl parathion to methyl paraoxon.
Oxygen analogs were more rapidly metabolized than the phosphoro-
thioates. Mouse liver was most efficient in demethylation reactions.
Glutathione was essential as a methyl acceptor or as an activator.
Benke et al. (1974) found the demethylation of methyl parathion
was via a glutathione-dependent liver enzyme. Fukunaga et al. (1969)—'
found that the metabolism of methyl parathion by rat liver microsomes
reqired reduced glutathione and liver soluble fraction. The conversion
of methyl parathion directly to desmethyl parathion was the principal
pathway in the presence of glutathione. Rao and McKinley (1969).3/
studied the metabolism of methyl parathion by liver homogenates from
chickens, rats, guinea pigs and rhesus monkeys. The demethylation
reaction was more active than the oxidative pathways.
\l Miyamoto, J., Y. Sato, K. Yamamoto, and S. Suzuki, "Activation and
Degradation of Sumithion, Methyl Parathion and Their Oxygen
Analogs by Mammalian Enzymes in vitro," Botyu-Kagaku, 33:1-7
(1968).
2/ Fukunaga, K., J. Fukami, and T. Shishido, "The in vitro Metabolism
of Organophosphorus Insecticides by Tissue Homogenates from Mam-
mal and Insect," Residue Rev.. 25:223-249 (1969).
3_/ Rao, S. L. N., and W. P. McKinley, "Metabolism of Organophosphorus
Insecticides by Liver Homogenates From Different Species," Can.
J. Biochem., 47:1155-1159 (1969).
61
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Tissue Residues - The binding of methyl parathion to the esterase
enzymes in an irreversible manner is the only tissue accumulation
that has been studied.
Summary -
1. Methyl parathion and its oxygen analog are readily absorbed
through the skin and from the stomach.
2. The distribution of injected methyl parathion is associated
with several tissues but is most concentrated in liver and
lung-
3. Excretion products of methyl parathion are mainly dimethyl
phosphoric acid, methyl phosphate, methyl phosphorothioate,
dimethylphosphorothioic acid and phosphoic acid.
4. Methyl parathion is converted to its toxic oxygen analog
by liver microsomes.
4. Demethylation is the principal in vitro detoxifying pathway of
methyl parathion in the presence of reduced gluththione.
Effects on Reproduction
Rats - An unpublished report by the Woodard Research Corporation
was reviewed by Anon., FAO/WHO (1969). This report was concerned
with a three-generation study in rats. The dose level was 0, ;10
and 30 ppm. In a two-litter-per-generation study there was no con-
sistent effect on the number of live or stillbirths, physical
structure of newborn, litter size, weanling weights or percen-
tage survival to weaning. The only consistent effect was reduced
productive performance in the Fla, Fib, F2a and F3b generation at
30 ppm. Sporadic effects included lower weanling survival rate
in Fla, Fib, and F2a generations at 30 ppm, and in F3a generation
at 10 ppm; increased stillbirth rate in Fib and F3a generations
at 30 ppm and F3a at 10 ppm; reduced mean weanling rate in F2a gen-
eration at 30 ppm and Fib generation at 10 ppm. There was no reduced
reproductive performance activity noted at the 10-ppm level* which
approximates 0.5 mg/kg/day.
62
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Avian Species - Shellenberger et al. (1968)i' found that egg
production of Japanese quail was inhibited. Hatchability was re-
duced by 60 ppm of methyl parathion. This was in contrast to
parathion where hatchability was reduced by 27 ppm.
Teratogenic Effects
Mammals - Fish (1966)—' reported on a teratology study with rats.
Dosage levels were 4 and 6 mg/kg. He obtained negative results
on a single dose in methyl parathion groups tested on days 9 and
15 of gestation. Only one embryo in the methyl parathion group
developed an axillary hematoma. Methyl parathion was administered
(4 mg/kg) to additional animals on the 9th and 15th day of gestation
and these animals were allowed to deliver. There were no still-
births or gross anomalies of the young for the animal injected on
the 9th day of gestation. The litter from the mother injected on
the 15th day of gestation resulted in one stillbirth and no gross
anomalies.
Tanimura et al. (1967)—' studied the teratogenic effects in
rats and mice that were injected intraperitoneally on day 12 of
gestation in the rats and on day 10 in the mice. The dosage was
5, 10 and 15 mg/kg body weight in the rats and 20 and 60 mg/kg
in the mice. The highest dose in both species was near the LD5Q-
All the animals of both species exhibited signs of toxicity 30
min after administration of the compound regardless of the dosage
level. The observations on the fetuses in rats and mice are shown
in Tables 11 and 12. He found no significant external or internal
malfunctions in rats, whereas the mice showed more embryotoxicity.
_!/ Shellenberger, T. E., J. B. Gough, and L. A. Escuriex, "Com-
parative Toxicity Evaluation of Organophosphate Pesticides
With Wildlife." Ind. Med. Surg., 37:537 (1968).
2/ Fish, S. A. , "Organophosphorus Cholinesterase Inhibition and
Fetal Development," Amer. J. Obstet; Gynecol., 96(8):1148-
1154 (1966).
3/ Tanimura, T., T. Katsuya, and H. Nishimura, "Embryotoxicity of
Acute Exposure to Methyl Parathion in Rats and Mice,:i Arch.
Environ. Health, 15:609-613 (November 1967).
63
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ON
Table 11. EFFECT ON OFFSPRING OF A SINGLE INTRAPERITONEAL INJECTION
OF METHYL PARATHION IN PREGNANT RATS ON DAY 12
Dosage
(mg/kg)
15
10
5
OS/
Data from
•-•• ••'">, ...
No. of
litters
(dead)
13
(3)
10
10
10
Tanimura
Offspring
Total no.
(litter size)
109
115
115
111
et al.. op. cit.
Dead
(%)
12
11
8
10
(1967),
Mean body
weight (g)
4.30
4.86
4.73
4.78
»
No. of
fetuses
examined
34
34
34
30
Skeletal
Cervical
rib
0
1
0
0
variations
Rib Asymmetry of
No. 14 sternebrae
2 3
0 E 1
1 4
0 2
a/ Sodium carboxymethyl cellulose.
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Table 12. EFFECT ON OFFSPRING OF A SINGLE INTRAPERITONEAL INJECTION OF METHYL PARATHION IN PREGNANT MICE ON DAY 10
Skeletal variations
State of ossification
ON
Oi
Dosage
(mg/kR)
60
20
t
OS/
No. of
litters
(dead)
14
(5)
11
8
Offspring
Total no.
112
143
102
Dead
25
6
2
Malformations!*/
13
2
0
Mean body
weight (O
1.16
1.26
1.25
No. of
fetuses
examined
30
37
30
Bifurcated
C-l or C-2
5
3
3
Cervical
rib
8
8
1
Rib
No. 14
1
1
1
Asymmetry of
sternebrae
2
3
0
Nonfused
Under-
supra- >- developed
occipital
2
0
1
sternebrae
0
5
1
Data from Tanimura et al., op. cit. (1967).
a/ Sodium carboxymethyl cellulose.
b/ Cleft palate.
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Lethality, teratogenicity, and suppression of growth was noted in the
group treated with the higher dosage. The major malformation in the
mouse, at high dosage, was cleft palate. The cleared specimens of the
rat did not indicate any skeletal malformations had taken place (Table 11)
In the mice nonfused supraoccipital occured at the 60 mg/kg dosage.
At the dosage of 20 mg/kg some incidence of underdeveloped sternebrae
occured. The investigators did not find these malformations signi-
ficant at the 5% level. However, in the 1968 FAO/WHO Report (Anon.,
FAO/WHO, 1969) the statement was made, "It was therefore found
necessary to reevaluate this compound by using a higher safety factor
which changes the acceptable daily intake to a temporary acceptable
daily intake." The estimate of temporary acceptable intake was set
at 0 to 0.001 mg/kg/body weight. The adjustments were predicated
on the observed teratogenic effects in mice after parenteral admin-
istration, and on the reproductive studies in rats that showed some
disturbances of the physiology of the reproductive process.
Behavioral Effects
No information was found in the literature on the behavioral
effects of methyl parathion.
Toxicity Studies With Tissue Culture
Huang (1973)!/ investigated the effect on cell growth after
treatment with three organophosphates: disulfoton, malathion and
methyl parathion. The evaluation was made with human hematopoi-
etic cell lines that were derived from blood of normal male indi-
viduals. The concentrations of methyl parathion were 25, 20, 75, and
100 ug/ml. Growth was reduced at all concentrations generally in pro-
portion to the concentration given. At 50 hr the media containing the
pesticide was removed and fresh media free of pesticide was added. A
rapid normal growth resumed except for the cells previously treated
with 100 ug/ml of methyl parathion. These cells died within the first
day.
if Huang, C. C., "Effect on Growth but not on Chromosomes of the Mam-
malian Cells After Treatment with Three Organophosphorus Insec-
ticides," Pr^c.Jac_.J&cp_._JioJi._Med. , 142(1):36-40 (1973).
66
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Mutagenlc Effects
Only one report was found that yielded information on mutagenic
studies in regard to methyl parathion (Huang, 1973). In this study
the effect of methyl parathion on chromosomes of cells in vivo was
studied using ICR male mice which had been injected intraperitoneally
with 5, 10, 20, 50 or 100 mg of the compounds per kilogram of body
weight. The mice that were injected with the higher doses of methyl
parathion (50 and 100 mg/kg) died within 1 hr after injection. All
the mice lived at the lower concentration for 24 hr after injection.
Bone marrow tissue for chromosome study was taken from the femurs.
Methyl parathion caused no increase in the incidence of chromosome
aberrations in cells. The authors suggested that the animals that
died at the higher dosage level very likely died due to nervous
system toxicity.
Oncogenic Effects
No information was found in the literature on long-term studies
relative to the oncogenic effects of methyl parathion.
Effect on Humans
Acute and Subacute Toxicity - No information was found for the lethal
dose of methyl parathion for man.
Through the I9601s Rider and his co-workers (1963, 1964, 1967,
1969a, 1969b)-^-' at the Franklin Hospital Foundation in San Francisco,
I/ Rider, J. A., and H. C. Moeller, "Tolerance of Organic Phosphates
in Man," Progress Report of Franklin Hospital Foundation, San
Francisco, California (1 October 1963).
2/ Rider, J. A., and H. C. Moeller, "Studies on the Anticholinesterase
Effects of Systox and Methyl Parathion in Humans," Fed. Proc..
23(2):176 (1964).
3/ Rider, J. A., H. C. Moeller, and E. J. Puletti, "Continuing Studies
~~ on Anticholinesterase Effect of Methyl Parathion, Initial Studies
With Guthion, and Dichlorvos in Humans," Fed. Proc.. 26(2):427
(1967).
4/ Rider, J. A., H. C. Moeller, E. J. Puletti, and J. I. Swader,
"" "Toxicity of Parathion, Systox, Octamethy1 Pyrophosphoramide, and
Methyl Parathion in Man," Toxicol. Appl. Pharmacol., 14(3):603-
611 (1969a).
5/ Rider, J. A., and'E. J. Puletti, "Studies on the Anticholinesterase
Effects of Gardona, Methyl Parathion, and Guthion in Human Sub-
jects," Fed. Proc., 28(2): 479 (1969b).
67
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evaluated tolerances to insecticides in experimental tests conducted
with volunteers from the California State Prison at San Quentin.
During these years these investigators worked with parathion, methyl
parathion, malathion, demeton, and azinphos methyl. They usually used
five subjects and two controls, and the insecticides were administered
daily in capsules for periods of approximately 30 days. Samples of
blood were taken prior to the test and twice a week throughout the
tests for cholinesterase evaluations. Their definition of incipient
toxicity was that amount of organophosphate ingested daily which pro-
duced an unequivocable depression of the average cholinesterase levels
of five subjects of between 20 to 25%. They administered methyl parathion
in one test (Rider and Moeller, 1963) at a level of 1 mg daily and
without significant depression of RBC cholinesterase. This dosage was
increased in subsequent periods of 0.5 mg increments to a level of 10
mg/day and did not establish an incipient toxicity. In another evaluation
(Rider et al., 1967), the methyl parathion dosage was increased in two
sets of subjects to 13 and 13-1/2 mg/day without depression of plasma
and RBC cholinesterase. Later Rider and Puletti (1969b) raised the daily
intake to dosages of 17, 18, 19, and 20 mg for 4 weeks. There was still
no significant change in plasma or RBC cholinesterase levels.
Symptoms of Methyl Parathion Poisoning - The description of symptoms for
organophosphates are generally treated without designating any peculiarity
of symptoms ascribed to any one individual chemical. . The symptoms described
for parathion poisoning by Sumerford et al. (1953),-' Arterberry et al.
(1961).—' Hamblin and Golz (1955), Tsachalinas et al. (1971),^/ and Namba
(1971)A/ are similar to methyl parathion.
JL/ Sumerford, W. T., W. J. Hayes, Jr., J. M. Johnston, K. Walker, and
J. Spillane, "Cholinesterase Response and Symptomatology From Ex-
posure to Organic Phosphorus Insecticides," AMA Arch. Ind. Hyg.
Occup. Med., 7:383-398 (1953).
2/ Arterberry, J. D., W. F. Durham, J. W.- Elliot, and H. R. Wolfe,
"Exposure to Parathion." Arch. Environ. Health, 3:476-485 (1961).
3_/ Tsachalinas, D., G. Logaras, and A. Paradelis, "Observations on
246 Cases of Acute Poisoning With Parathion in Greece," Eur. J.
Toxicol., 4:46-49 (1971).
4_/ Namba, T., "Cholinesterase Inhibition by Organophosphorus Compounds
and Its Clinical Effects," Bulletin of the World Health Organiza-
tion, 44:289-307 (1971).
68
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Namba (1971) has classified other signs and symptoms observed in
77 patients who developed poisoning by the application of ethyl and
methyl parathion. The more prominent symptoms were weakness, nausea
or vomiting, excessive sweating, headache, excessive salivation and
difficulty in walking. Namba points out that if the exposure to an
organophosphate insecticide is sufficient enough to develop symptoms,
they usually appear in less than 12 hr. Symptomatology that appears
24 hr after exposure cannot be attributed to these pesticides. A
critical clinical observation is the occurrence of miosis, which is
found in about 50% of the patients, and appears even in subjects with
mild cases. Death is usually attributed to failure of the respiratory
muscles and paralysis of the respiratory center. Cardiac involvement
may occur but it is usually at the terminal stage. Man appears to be
more sensitive to the organophosphate insecticides, showing signs of
symptoms earlier than experimental animals particularly central nervous
system manifestations. If an untreated organophosphorus-poisoned vic-
tim is alive after 24 hr, he will recover. The account by Kanagaratnam
et al. (I960)— describes a parathion poisoning incident from contam-
inated barley in India. There were 53 persons involved and the clini-
cal features were described in some detail, concerning collapse, fits,
sweating, dyspnea, miosis, unstable blood pressure, coma, and muscular
fasciculation.
Namba (1971) also presented an excellent description of the signs
and symptoms of organophosphate poisoning in patients. Reference
should be made to Hamblin and Golz (1955) for the onset and progres-
sions of symptoms in subjects exposed to toxic amounts of parathion
in spraying operations.
The pharmacology and toxicology of parathion poisoning have also been
described by Hamblin and Golz (1955). These authors state that the
only important pharmacological action of parathion is its action in
the inhibition of enzyme acetylcholinesterase. This enzyme catalyzes
the hydrolysis of acetylcholine. The absorption of parathion brings
about the accumulation of acetylcholine, because of a failure in the
disposal mechanism in parasympathetic postganglionic fibers, in sympa-
thetic ganglia, and in the central nervous system, as well as at the
I/ Kanagaratnam, K., W. H. Boon, and T. K. Hoh, "Parathion Poisons
From Contaminated Barley," Lancet, 1:538-542 (1960).
69
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myoneural junctions of muscle. In acute poisoning, manifestations
usually occur only after more than 50% of the plasma cholinesterase
is inhibited. After an acute poisoning it takes about 4 weeks for
plasma cholinesterase to return to normal and about 5 weeks for RBC
cholinesterase.
Gershon and Shaw (1961)!,/ followed^the case histories of 16 persons
suffering from psychiatric disorders, who had also been chronically
exposed to organophosphorus pesticides for periods of time ranging
from 1-1/2 to 10 years. Of the 16 cases studied, three were scien-
tific workers, eight worked in greenhouses and five were farmworkers.
Although all suffered some form of mental disorder, mental history
prior to exposure to pesticides was not always known. Likewise sever-
ity of exposure and type of pesticides used were not always known. In
general, schizophrenic and depressive reactions were observed with
severe impairment of memory and difficulty in concentration. In a
follow-up of four cases the symptoms persisted for 6 months after
exposure ceased with reversion to normal in 12 months. As a result
of a small field survey the authors suggest, "Psychiatric disorders
might be commoner in fruit-growing areas than in towns."
No other surveys of this nature were found in the literature.
Fazekas (1971).?/ reported on the conditions at autopsy of 30 per-
sons fatally poisoned by methyl parathion. Death had occurred in 2 to
9 days after oral ingestion. The subjects varied in age from 18 to 82
years. The principal changes noted were edema and hyperemia. Where
death was prolonged, degenerative changes were observed. When death
occurred unexpectedly, hemorrhages occurred in the myocardium and
medulla oblongata. The hemorrhages were characterized as being mul-
tiple pericapillary and periprecapillary.
TJ Gershon, S., and F. H. Shaw, "Psychiatric Sequelae of Chronic
Exposure to Organophosphorus Insecticides," Lancet, pp. 1371-1374
(1961).
2/ Fazekas, I. G., "Macroscopic and Microscopic Changes in WOFATOX
(Methyl Parathion) Intoxication," Z. Rechtsmed. 68:189-194 (1971).
70
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Dermal Effects - No Information was found in the literature on dermal
toxicity of methyl parathion to humans.
Inhalation Effects - There was no data found concerning the inhalation
toxicity of methyl parathion in humans.
Occupational and Accidental Exposure Hazards - In a broad sense occu-
pational exposure hazards can be defined as exposure in field opera-
tions and in manufacturing plants.
Field operations - There have been a few reports on the potential
exposure hazard to methyl parathion by workers in field operations.
Quinby et al. (1958)—' reported that the exposure while checking cotton
from insect damage was 0.7 mg/hr dermal. The amount per hour taken in
by the respiratory route was below the limits of the analytical method.
Nemec et al. (1968) studied the absorption of methyl parathion by
persons checking cotton treated with ultralow volume (ULV) sprays.
The study was made with two entomologists as subjects. The clothing
worn by these observers was normal wear plus sleeveless laboratory
uniforms. Their arms and hands were washed separately after they came
from the treated fields.
The data in Table 13 indicates that the men absorbed substantial
amounts of methyl parathion.
The RBC cholinesterase of the men was determined from 12 June
through 13 August 1967. From 12 June to 4 August, the activity
ranged between 90 and 95% of normal. On 30 August, the activity -level
for both men fell to 60% of normal. Previous to this date they had
worked in the methyl parathion field on 16 August, 2 hr after spray-
ing; 22 August, 24 hr after spraying, and 30 August, 2 hr after spray
was applied.
If Quinby, G. E., K. C. Walker, and W. F. Durham, "Public Health Hazards
Involved in the Use of Organic Phosphorus Insecticides in Cotton
Culture in the Delta Area of Mississippi," J. Econ. Entomol., 51:
831-838 (1958).
71
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Table 13. AMOUNTS OF METHYL PARATHION ABSORBED
BY MEN WORKING IN ULV-TREATED FIELDS
Time of exposure Methyl parathion (mg)
Exposure after treatment Pounds of Left Right
date (hr) Al/acre arm arm Total
August Entomologist 1 (180 Ib)
16 2 2 0.752 1.272 2.024
22 24 1.5 0.077 0.086 0.163
30 2 . 2 1.916 2.424 4.340
Entomologist 2 (240 Ib)
16 2 2 1.666 2.710 4.340
22 24 1.5 0.153 0.198 0.351
30 2 2 3.883 6.029 10.092
Source: Nemec et al., op. cit. (1968).
Reprinted from J. Econ. EntomoL, by permission of the
Entomological Society of America.
These results indicate that the potential hazard is high when fields
are entered 2 hr after spraying. Furthermore, treated fields should not
be entered until 24 hr after treatment.
As has been reported by Ware et al. (1973)!/ the determination of
safe reentry intervals is influenced by a number of factors including,
(1) frequency and rate of application, (2) characteristics of the foliage,
(3) height of the foliage, (4) density of the canopy, (5) the weather,
and (6) inherent characteristics relative to the particular pesticide
applied, i.e., persistance, toxicity, penetrability, etc. Other fac-
tors involved are the length of exposure time, the type of clothing
worn, and the presence or absence of respiratory protection. The recom-
mended reentry time established must be long enough to give protection
to the worker but short enough to be tenable with profitable agricultural
practice.
I/ Ware, G. W., D. P. Morgan, B. J. Estesen, W. P. Cahill, and D. M.
Whitacre, "Establishment of Reentry Intervals for Organophosphate-
Treated Cotton Fields Based on Human Data:. I. Ethyl and Methyl
Parathion," Arch. Environ. Contain. Toxicol.. l(l):48-59 (1973).
72
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In the study reported by Ware et al. (1973) concerning the aerial
application of a mixture containing 0.5 Ib of methyl parathion, 0.5 Ib
of ethyl parathion and 2.0 Ib of toxaphene in 5 gal. of spray per acre,
the crop was mature cotton, with bolls beginning to open. Ten minutes
after application, two men entered the field and collected samples for
30 min; this operation was repeated at 12, 24, 48, and 72 hr after in-
secticide treatment.
Biomedical data indicated that there was no clinical evidence of
plasma or RBC cholinesterase depression or of urinary £-nitrophenol in
either subject (man) even when the field was entered immediately after
treatment.
Ware et al. (1973) reported that from the accumulation of residues
on skin and clothing an individual can expect exposure to the following
amounts of mixed residues during a 30-min period at the times indicated
after treatment of a cotton field with methyl parathion and parathion.
Time After Hands and Clothing Inhalation
Treatment (hr) Forearms (me) (me) (roe/ml)
0 3.47 18.21 1.06
12 1.93 12.11 0.60
24 1.16 6.57 0.36
48 0.60 4.52 0.18
72 0.31 2.65 0.09
The authors suggest that, with cotton, reentry can be safely
made 12 to 24 hr after spraying with parathion-methyl parathion
mixtures.
Roan et al. (1969)— made a study of blood cholinesterase, serum
parathion concentrations, and urine £-nitrophenol concentrations in
exposed individuals. They used aerial applicators, loaders, and floggers
as subjects. The sprayers were using ethyl and methyl parathion. They
determined that the pesticide concentration correlated well with p_-
nitrophenol concentrations. They found that erythrocyte and/or plasma
I/ Roan, C. C., D. P. Morgan, N. Cook, and E. H. Paschal, "Blood Cholin-
esterases, Serum Parathion Concentrations and Urine £-Nitrophenol
Concentrations in Exposed Individuals," Bull. Environ. Contarn.
Toxicpl., 4(6):362-369 (1969).
73
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cholinesterase values are not as sensitive as indices of ethyl and
methyl parathion absorption as are the concentrations of these com-
pounds in serum. They concluded that there are extreme differences
in individual susceptibility to the actions of organic-phosphorus
compounds.
Manufacturing operations - Only one reference was found with in-
formation on repeated exposures to methyl parathion in manufacturing
plants. Hartwell and Hayes (1965)i' made observations over a 4-year
period on two plants. Both plants produced parathion and methyl para-
thion. The respiratory protection in both plants was quite different
in adequacy at the beginning of their observations in 1960. Plant A
was substandard in operation. Ventilation was inadequate and loading
of the pesticide mixer -was manual. Plant B was considered a modern
facility. The ventilation was adequate, only nontoxic dusts were
handled manually, and the insecticide concentrates were forced into
the mixer by compressed air.
Poisoning cases were identified by symptoms and depression of
cholinesterase levels by 207o or more. In Plant A in 1960 there were
17 cases of poisoning, and depressed cholinesterase levels (20% or
more) were noted 41 times in 26 workers. In 1961 an uncontaminated
compressed air system was installed allowing the replacement of the
filter masks used by the workers. No poisoning cases occurred and
the KBC cholinesterase activity was depressed four times .among 13
workers. Depression was detected seven times in 1962 among 15 workers
and six times in 1963 among 11 workers.
Although Plant B was a modern plant, it had to stop production in
1960 because of the occurrence of poisoning cases. The air compressor
in this plant supplied air to the workers and was used simultaneously
for forcing concentrates to the mixer. In 1961 seven cases of poisoning
and nine depressions in cholinesterase activity were observed in 23
workers. The picture did not improve until 1963. In that year, a com-
pressor was provided for each operation; the number of poisoning cases
fell to zero and only three instances of depressed cholinesterase
activity were observed.
JY Hartwell, W. V., and G. R. Hayes, Jr., "Respiratory Exposure to
Organic Phosphorus Insecticides," Arch. Environ. Health, 11:
564-568 (1965).
74
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A study has been made of the contamination of special clothing and
skin coverings of workers in the manufacture of methyl parathion
(Trefilov et al., 197ll/). In general, the permissible concentration
of methyl parathion in the air was not exceeded. The workers wore gas
masks during the shifts. Dermal contamination was picked up from con-
taminated equipment. Residues were picked up around the wrists. Lesser
residues were found on the chest and forehead areas. A significant de-
pression of cholinesterase was found in the workers. Heinz bodies were
found in the erythrocytes and p_-nitrophenol was detected in the urine.
Accidents - Methyl parathion is one of the pesticides most fre-
quently cited in incidents involving accidental exposure to pesticides.
Preliminary data from the EPA Pesticide Accident Surveillance System
(PASS)* shows that methyl parathion is the fifth most frequently cited
pesticide for all episodes reported in 1973. Based on an analysis of
PASS data, Osmun (1974)1' stated that for 1972 and 1973, about 7870 of
the episodes reported related to agricultural jobs and involving
pesticides for which reentry times have been proposed involved methyl
parathion and/or parathion.
There are a number of limitations, however, in attempting to use
PASS data. First of all, the cause-effect relationship between the
pesticides cited and the effects observed have generally not been es-
tablished. Second, generally only data for 1972 through about January
1974 have been computerized and are readily available for retrieval.
Third, a large portion of the data provided to PASS comes from California.
This skewed distribution probably represents bias caused by the efficient
level with which the State of California documents pesticide information.
During our review of PASS files, data in addition to the preliminary in-
formation found on the pesticide episode reporting form (Form ACEC-1
Dec 1972) were found on only nine of the approximately 125 episodes in-
volving methyl parathion. Further duplicate entries in PASS have been
noted for a few incidents.
* Episodes reported include those involving humans, animals, plants,
and area contamination.
I/ Trefilov, V. N., Jr., I. S. Faernan, Jr., and E. P. Borisona, Jr.,
"The Degree of Contamination of the Special Clothing and Skin
Coverings of Workers in the Manufacture of Metaphos and Chlorophos,"
Gigiena Truda I Prof. Zobolevoniga, 15(2):51-53 (1971).
2f Osmun, J. V., Internal EPA Memo to Ed Johnson, "PASS Information Re-
lating to Agricultural Jobs" (I.April 1974).
75
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Some 125 episodes involving methyl parathion are included in the
PASS computerized system. Approximately 45, 30, and 1570 of these
episodes were reported from EPA Regions IV, VL , and IX, respectively.
This distribution is not inconsistent with that of the domestic con-
sumption pattern discussed later under the subsection "Production and
Use."
On 10 June 1974, protection standards for agricultural workers in
fields treated with methyl parathion became effective (Quarles, 19741/).
These standards prohibit application of methyl parathion when unpro-
tected workers are in the area being treated, and require that unpro-
tected workers not enter fields treated with this pesticide for at
least 48 hr.
Summary of Toxic Effects Other Than Acute, Subacute, and Chronic
Toxicity
In one study on the effect of methyl parathion on reproduction
(rats), it was noted that reproductive performance was not reduced at
a dosage of 10 ppm, but was consistently reduced at 30 ppm. In another
study it was shown that a daily intake of 60 ppm reduces the hatchability
of quail eggs.
The teratogenic effects of methyl parathion have been studied in
rats. In one study no gross anomalies were produced in the embryo or
in the young when the mothers were injected with 4 and 6 mg/kg of methyl
parathion. Another investigation did not indicate any malformation of
young rats when the dosage was raised to 15 mg/kg of body weight.
Lethality, suppression of growth and some teratogenic effects were pro-
duced in the young of mice when the injected dosage was raised to 60
mg/kg. The significant malformation was cleft palate at the 60 mg/kg
of body weight dose level. Some incidence of cervical rib variation
occurred at 60 mg/kg, and it was significant at the 5% level«
There was no data found on avian embryotoxicity. There were also
no reports found on the possible oncogenic effects of methyl parathion.
I/ Quarles, J., "Worker Protection Standards for Agricultural Pesticides,"
"" Federal Register. 39(62):16888-16891 (10 May 1974).
76
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Methyl parathion does affect cell growth in tissue culture after
treatment with 25 to 100 ug/ml. At the higher level (100 ug/ml) all
the cells die in 1 day. /
No chromosome aberrations were found in bone marrow cells of mice
that had been injected with 5, 10, and 20 mg/kg of body weight of
methyl parathion.
The number of reports that have been published in the literature
on the effect of methyl paraithion in humans is surprisingly small. No
information was found to indicate the lethal dose of -methyl parathion
for man. It is known that humans can tolerate 20 mg of methyl parathion
daily for 4 weeks without any significant changes in plasma or RBC
cholinesterase levels.
The depression of blood cholinesterase activity is a sensitive
diagnostic tool; pathology observed at autopsy is not gross in nature.
No information was final with regard to controlled dermal or in-
halation exposure to humans.
The symptoms of methyl parathion poisoning have been delineated
in a number of reports. The progress of the symptomatology appears
to be quite similar to other organosphosphorus compounds. The symptoms
are of an acute nature, and chronic symptoms are only mild manifesta-
tions of the acute symptoms.
It has been shown that there are exposure hazards to workers if
sprayed cotton fields are entered shortly after an application of methyl
parathion. Very little information is available on the hazards that may
prevail in manufacturing operations. It is reasonable to assume that
the wearing of protective clothing and efficient respirators along with
the observance of good manufacturing practice will eliminate to a
significant extent the risk involved in these operations.
77
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78
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83
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SUBPART II. C. FATE AND SIGNIFICANCE IN THE ENVIRONMENT
CONTENTS
Page
Effect on Aquatic Species 86
Fish ' 86
Laboratory Studies 86
Field Studies 89
Lower Aquatic Organisms 92
Laboratory Studies 92
Field Studies 93
Effects on Wildlife 98
Laboratory Studies 98
Field Studies 99
Effects on Beneficial Insects 102
Interactions with Lower Terrestrial Organisms 103
Residues in Soil 105
Laboratory Studies 105
Field and Combined Field-Laboratory Studies 107
Monitoring Studies 107
Summary 110
Residues in Water 110
Laboratory and Field Studies 110
Residues in Air >:'. 112
Residues in Nontarget Plants 113
84
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CONTENTS (Continued)
7 Page
Bioaccumulation, Biomagnification 114
Environmental Transport Mechanisms 114
References 116
85
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This section contains data on the environmental impact of methyl
parathion. Laboratory and field studies investigated effects on aquatic
species, lower aquatic organisms and wildlife. Studies also evaluated
methyl parathionfs effects on beneficial insects, interactions with lower
terrestrial organisms and effects on residues in soil, water, air and
nontarget plants. The section summarizes rather than interprets data
reviewed.
Effects on Aquatic Species
Fish -
Laboratory studies - The toxicity of methyl parathion to fish has
been tested in a large number of species (Table 14). The scientific
names are given in Table 15.
Of the species tested, the range in sensitivity of freshwater fish
to methyl parathion (96-hr LC5Q values) is from the most sensitive (blue-
gill LC50 1.9 ppm) to the least sensitive (fathead minnow LCso 8 to 10.4
ppm and the carp LC^Q 7.13 ppm). There was one high value (LDso 24 hr)
reported for pumpkinseed sunfish ( 2,500 mg/kg). It should be noted
that this LDso value was obtained through an intraperitoneal injection
technique and cannot be considered comparable to either LCso values or
to conventional LD5Q values derived from introducing a chemical direction
into the stomach via gavage.
For estuarine and saltwater fishes tested, the range in 96-hr LCcQ
values is from 5.7 ppm for the Atlantic silverside to 75.8 ppm for the
Northern puffer.
The relationship of brain AChE inhibition to death after exposure
to methyl parathion was determined by Coppage (1972)!/ following single
exposure to acute doses that killed 40 to 60% of sheepshead minnows.
I/ Coppage, D. L., "Organophosphate Pesticides: Specific Level of Brain
AChE Inhibition Related to Death in Sheepshead Minnows," Trans.
Am. Fish. Soc.. 101(3):534-536 (1972).
86
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Table 14. ACUTE TOXICITY TO FISH
Toxlcity level
Exposure Toxicity effect measured as
time (hr) calculated by (ppm) Reference
Fish
Bluegill
Bluegill
Bluegill
Bluegill
Rainbow trout
Brown trout
Yellow perch
Redear sunfish
Sunfish (pumpkin-
seed)
Largemouth bass
Coho salmon
Channel catfish
Channel catfish
Black bullhead
Carp
Fathead minnow
Fathead uinnow
Fathead minnow
Goldfish
Goldfish
Guppy
Atlantic silverside
Bluehead
Striped killifish
Mummichog
Northern puffer
Northern puffer
Siamese fighting
fish
American eel
Mosquitofish
Golden shiner
Green sunfish
96
24
96
96
96
96
96
96
24
96
96
96
24
96
96
96
96
96
96
96
96
96
96
96
96
96
16 Days
120
96
96
48
48
LC55
TLm
TLm
TLm
TLm
TLm
TLm
1.6
6.47
5.72
1.90
2.75
4.74
3.06
5.17
I/
*/
b/
!/
b/
b/
b/
b/
LDSO
LC50
TL,,,
TLm
TLm
TLm
TLm
LC50
LC50
LC50
LC50
LC50
Total mortality
LC50
LC50
LC50
LC50
LC50
>2,500 ppm
.22
.30
.71
.36
.64
.13
8.90
8.0
10.4
9.0
9.6
7.8
5.7
12.3
13.8
58.0
75.8
0.02
(20.2 ppb)
7.6
16.9
0.005
75.0
>5.0
b/
£/
I/
*/
8
zl
&!
k/
_a/ McCann, J. A., and R. L. Jasper, "Vertebral Damage to Bluegills
Exposed to Acutely Toxic Levels of Pesticides," Trans. Am. Fish.
Soc.. 101(2):317-322 (1972).
b/ Macek, K. J., and W. A. McAllister, "Insecticide Susceptibility of
Some Common Fish Family Representatives," Trans. Am. Fish. Soc..
99(1):20-27 (1970).
c/ Pickering, Q. H., C. Henderson, and A. E. Lemke, "The Toxicity of
Organic Phosphorus Insecticides to Different Species of Warm-
Water Fishes," Trans._Am._Fish._Joc., 91(2) : 175-184 (1962).
d/ Benke, G. M., K. L. Cheever, F. E. Mirer, and S. D. Murphy, "Com-
parative Toxicity Anticholinesterase Action and Metabolism of
Methyl Parathion in Sunfish and Mice," Toxicol. Appl. Pharmacol.,
28:97-109 (1974).
ej Carter, F. L., "In vivo Studies of Brain Acetylcholinesterase
Inhibition by Organophosphate and Carbamate Insecticides in Fish,"
Piss. Abstr.. 32(5):27, 2-73 (1971).
f/ Henderson, D., and Q. H. Pickering, "Toxicity of Organic Phosphorus
Insecticides to Fish," Trans. Am. Fish. Soc.. 87:39-51 (1958).
£/ Eisler, R., "Acute Toxicities of Organochlorine and Organophos-
phorus Insecticides to Estuarine Fishes," Technical Papers of
the Bureau of Sport Fisheries and Wildlife. No. 46, pp. 1-12
(March 1970a).
h/ Eisler, R., "Tissue Changes in Puffers Exposed to Methoxychlor and
Methyl Parathion," Technical Papers of the Bureau of Sport Fish-
eries and Wildlife. No. 17, pp. 1-15 (September 1967).
il Welsh, M. J., and C. W. Hanselka, "Toxicity and Sublethal Effects
of Methyl Parathion on Behavior of Siamese Fighting Fish (Betta
splendens)." Tex. J. Sci.r 23(4):519-529 (1972).
J/ Muncy, R. J., and A. D. Oliver Jr., "Toxicity of 10 Insecticides to
the Red Crawfish, Procambarus dark (Girard). Trans. Am. Fish. Soc..
92:428-431 (1963).
k/ Minchew, C. D. and D. E. Ferguson, "Toxicities of Six Insecticides to
Resistant and Susceptible Green Sunfish and Golden Shiners in Static
Bioassays," J. Miss. Acad. Sci.. 15:29-32 (1970).
I/ Carter, F. L., and J. B. Graves, "Measuring Effects of Insecticides
on Aquatic Animals." LA Agr.. 16(2):14-15 (1973).
87
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Table 15. COMMON AND SCIENTIFIC NAMES OF FISH USED IN CONTROLLED
TOXICITY TESTS WITH METHYL PARATHION
Common name
American eel
Bluegill sunfish
Rainbow trout
Brown trout
Yellow perch
Redear sunfish
Pumpkinseed sunfish
Largemouth bass
Coho salmon
Channel catfish
Black bullhead
Carp
Fathead minnow
Goldfish
Guppy
Atlantic silverside
Bluehead
Striped killifish
Mummichog
Northern puffer
Tilapia
Siamese fighting fish
Mosquitofish
Green sunfish
Golden shiner
Scientific name
Anguilla rostrata
Lepomis macrochirus
Salmo gairdneri
Salmo trutta
Perca flavescens
Lepomis microlophus
Lepomis gibbosus
Micropterus salmoides
Oncorhynchus kisutch
Ictalurus punctatus
Ictalurus melas
Cyprinus carpio
Pimephales promelas
Carassius auratus
Lebistes reticulatus
Menidia menidia
Thalassoma bifasciatum
Fundulus majalis
Fundulus heteroclitus
Sphoeroides maculatus
Tilapia aurea
Betta splendens
Gambusia affinis
Lepomis cyanellus
Notemigonus crysoleucas
-------
In exposures up to 72 hr, the lethal brain AChE level was determined to
be 18% of normal. Further, Coppage stated that "... . AChE activity be-
low this level (18% of normal) indicates death from organophosphate
poisoning has occurred or will occur within about 24 hr."
In general the signs and pathology following methyl parathion
poisoning of fish are similar to those induced by other organic-phos-
phorus insecticides (e.g., parathion). From the description in two fish
studies (Henderson and Pickering, 1958;!/ Carter, 1971)!/ the following
changes can be expected to occur in fish after ingestion or exposure
to a lethal dose of methyl parathion: darkening of the skin, hyper-
activity, body tremors, lethargy, scalosis, loss of equilibrium,
opercular or gaping paralysis, and death.
One response that may be considered to be somewhat characteristic
of acute poisoning of fish with methyl parathion (and perhaps other
organic-phosphorus insecticides) is the extreme forward position of the
pectoral and pelvic fins when the fish are intoxicated.
McCann and Jasper (1972)A/ observed hemorrhaging in bluegill fin-
ger lings exposed to methyl parathion at levels ranging from 3.9 to 6.9
ppm. Fractures of the caudal vertebrae were associated with the
hemorrhaging. The injuries were observed at dose levels both above
and below the LC^Q (6.47 ppm). The excitability of the fish was also
affected. Disturbance of the fish in the early hours of exposure led
to increased mortality and increased hemorrhage rate.
Field studies - Most of the data available on the toxicity of methyl
parathion to fish under field conditions orginate from the use of this
insecticide for the control of the Clear Lake gnat (Chaoborus astictopus),
in Clear Lake, Lake County, California.
Hazeltine (1963)—' determined the following toxicity data for methyl
parathion: newly hatched first instar Clear Lake gnat larvae, 24-hr ex-
posure, LCgo* 0.0015 ppm; fourth instar larvae, 24-hr exposure, 0.021 ppm;
bluegill sunfish, 10-day exposure, LC5Q, 0.115 ppm. The bluegill sunfish
(Lepomis macrochirus) was selected as the test organism because it had
been shown in previous tests to be the species most susceptible to
organophosphate insecticides in the lake fish population. These data
indicated a substantial safety margin between the rate of methyl parathion
necessary for insect control and concentrations that would harm .fish.
I/ Hazeltine, W. E., "The Development of a New Concept for Control of the
Clear Lake Gnat," J. Econ. Entomol. 56(5):621-626 (1963).
2/ Henderson, C., and Q. H. Pickering, "Toxicity of Organic Phosphorus
Insecticides to Fish," Trans. Am. Fish. Soc.. 87:39-51 (1958).
3/ Carter, F. L., "In vivo Studies of Brain Acetylcholinesterase Inhibition
by Organophosphate and Carbamate Insecticides in Fish," Piss. Abstr.
32(5):27, 2-73 (1971).
.47 McCann, J. A., and R. L. Jasper, "Vertebral Damage to Bluegills Exposed
to Acutely Toxic Levels of Pesticides," Trans. Am. Fish. Soc.. 101
(2):317-322 (1972).
89
-------
Methyl parathion was subsequently applied repeatedly to Clear Lake
at doses of .0023 and .0033 ppm. Cook and Conners (1963)!./ made extensive
studies on the effects of these methyl parathion treatments on fish and
other aquatic organisms in the treated area. They gave no numerical
data, but concluded that the insecticide treatments had minimal or no
adverse effect on some 20 species of fish that had been recorded to be
present in the lake in previous studies.
Cook (1965)—' reported that none of the species of fish in Clear
Lake utilized gnat larvae as their principal food item, with the pos-
sible exception of the Sacramento perch (Archoplites interruptus) based
on the examination of over 2,000 stomach contents from all species of
fish in the lake.
Mulla et al. (1963) -/ investigated the toxicity of methyl parathion
and other insecticides to some aquatic wildlife species, including the
mosquitofish. (Gambusia affinis). Methyl parathion was applied to 1/16-
acre field ponds at a volume of 8 gal/acre as an aqueous spray prepared
from an emulsion concentrate containing 7.5 Ib Al/gal. At the rate of
0.8 Ib Al/acre, methyl parathion produced 10% mortality of mosquitofish
1 and 2 days after treatment. At the rate of 0.4lb Al/acre, mosquitofish
mortality was zero 1 day after treatment, 2% after 2 days. All mosquito
fish survived a methyl parathion application at the rate of 0.1 Ib AI/
acre.
Macek and McAllister—' (1970) conducted 96-hour static bioassays
using several pesticides, including methyl parathion, on several
representative species of four fish families to determine the relative
susceptibility of these species to different pesticides. Reconstituted,
deionized water at a temperature of 13i0.5 C for salmonids and 18^0.5 C
for other fish was used. Weight of test fish ranged from 0.6 to 1.7
grams. All LC5Q values are based on the active ingredient of the
formulations used. Results are presented in Table 14.
I/ Cook, S. F., Jr., and J. D. Conners, "The Short-Term Side Effects of
the Insecticidal Treatment of Clear Lake, Lake County, California,
in 1962," Annals of the Entomol. Soc. of America, 56(6):819-824
(1963).
2/ Cook, S. F., Jr., "The Clear Lake Gnat: Its Control, Past, Present,
and Future," California Vector Views. 12(9):43-47 (1965).
3_/ Mulla, M. S., L. W. Isaak, and H. Axelrod, "Field Studies on the
Effects of Insecticides on Some Aquatic Wildlife Species," J^
Econ. Entomol., 56(2):184-188 (1963).
4/ Macek, K. J., and W. A. McAllister, "Insecticide Suspectibility of
Some Common Fish Family Representatives," Trans. Am. Fish. Soc.,
99(1):20-27 (1970).
90
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Ferguson and Boyd (1964)i/ exposed mosquitofish (Gambusia affinis)
from two different locations to various rates of methyl parathion. Re-
sistance of mosquitofish to chlorinated hydrocarbon insecticides had
been reported in populations living near heavily sprayed cotton fields
in western Mississippi. The mosquitofish population from an area of
heavy use of cotton insecticides (Leflore County, Mississippi) was con-
siderably less susceptible to methyl parathion than a control population
known to be nonresistant at least to chlorinated hydrocarbon insecticides.
Carter!/ showed, in a field study of channel catfish, Ictalurus
punctatus, in waters in a drainage area of a cotton-soybean agroecosystem
receiving 8 to 16 yearly applications of methyl parathion (0.45 to 0.89
kg/ha), fish contained residues of methyl parathion and he showed brain-
AChE inhibition in other fishes.
The Federal Water Pollution Control Administration's publication
"Water Quality Criteria" (1968)1/ places methyl parathion in the cate-
gory "other pesticides." This group includes approximately 100 pesti-
cides in general use for which data on the acute toxicity to aquatic
organisms are available. "These chemicals are either not likely to
reach the marine environment, or if used as directed by the registered
label, probably would not occur at levels toxic to marine biota. It is
presumed that criteria established for these chemicals in freshwater
will protect adequately the marine habitat."
The 48-hr TLm of methyl parathion to bluegill is listed as 8,000
ug/liter (8 ppm), compared to 47 ug/liter (0.47 ppm) for parathion
(Federal Water Pollution Control Administration, 1968).
Minchew and Ferguson-t/ (1970) studied acute effects of several
pesticides, including methyl parathion, on susceptible and resistant
populations of green sunfish (Lepomis cyanellus) and golden shiner
(Notemigonus crysoleucas) by running 48-hr static bioassays.
For each concentration tested, 20 fish were placed in each of two
30 1 aquaria. Four or five concentrations were tested to calculate each
median lethal concentrations (LC50). Tap water was used in all bioassays;
water temperature was 68 "t 4 F (20 ± 2.2C). Estimated LC5Q values were
greater than 5 ppm for susceptible populations of both green sunfish and
golden shiner.
I/ Ferguson, D. E., and C. E. Boyd, "Apparent Resistance to Methyl Para-
thion in Mosquitofish, Gambusia affinis," Copeia No. 4:706 (1964).
2J Carter, F. L., "In vivo Studies of Brain Acetylcholinesterase Inhibi-
tion by Organophosphate and Carbamate Insecticides in Fish," Piss.
Abstr., 32(5):27, 2-73 (1971).
3_/ Federal Water Pollution Control Administration, Water Quality Criteria,
Report of the National Technical Advisory Committee, p. 37 (1968).
4/ Minchew, C. D. and D. E. Ferguson, "Toxicities of six insecticides to
resistant and susceptible green sunfish and golden shiners in static
bioassays." J. Miss. Acad. Sci., 15:29-32 (1970).
91
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In a study reported by Kennedy and Eller (1969)i/ the chronic tox-
icity of methyl parathion was determined for catfish and goldfish. One
hundred fish of each species were stocked in separate ponds. The ponds
were treated with 200 ppb (0.2 ppm) methyl parathion and sampled at the fol-
lowing times: pretreatment, 1, 3, 7, 14, 28, 56, and 84 days. During the
experimental period the total fish loss was 6% for goldfish and 8% for
catfish. This was considered normal mortality and presumably compared
favorably with observed mortality in the untreated ponds.
None of the fish showed signs of distress after treatment. The
pathology of catfish liver was characterized by marked cytoplasmic
vacuolization of hepatic cells. A sharp increase in cytoplasmic gran-
ularity of hepatic cells characterized liver damage in the goldfish.
Examination of control fish and fish given multiple exposures of methyl
parathion were incomplete at the time of presentation of the data.
These data indicate that methyl parathion is considerably less
toxic to fish than parathion.
Lower Aquatic Organisms -
Laboratory studies - In a study on red crawfish, Muncy and Oliver
(1963).2/ reported that there was no detectable difference in the toxicity
of methyl parathion to male or female crawfish although methyl parathion
was found to be very toxic to these crustaceans (Table 16). They re-
ported that the reaction to the presence of methyl parathion was evi-
dent in red crawfish at less than 1 ppm and that death occurred in less
than 3 hr. The 72-hr median tolerance limit (TLm) was determined to be
0.04 ppm.
I/ Kennedy, H. D., and L. L. Eller, "Chronic Effects of Methyl Parathion
and Endrin on Channel Catfish and Goldfish in Ponds," in Progress
in Sport Fishery Research: 1968, U. S. Bureau of Sport Fisheries
and Wildlife, Division of Fishery Research, Resource Publication
No. 77, 103-107 (1969).
2J Muncy, R. J., and A. D. Oliver, Jr., "Toxicity of 10 Insecticides
to the Red Crawfish, Procambarus clarki (Girard)," Trans. Am.
Fish. Soc., 92:428-431 (1963).
92
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The acute toxicity values (LC50 96 hr) of methyl parathion for the
sand shrimp, grass shrimp, freshwater shrimp, and for the hermit crab
(Eisler, 1969 I/ and 1970b) was 0.002, 0.003, 0.011, and 0.007 ppm, re-
spectively.
In contrast to the lability of methyl parathion on crops, Eisler
(1970a) reported that in brackish water a concentration of methyl
parathion of 0.5 ppm remained toxic for young blue crabs and juvenile
brown shrimp for at least 45 days.
Albaugh (1972) 2/ studied the difference in susceptibility of cray-
fish (Procambarus acutus) taken from clean water as compared to cray-
fish taken from water containing runoff from cotton fields. The 48-hr
LC5Q for the clean area crayfish was 2.4 ppb (.0024 ppm) (range 1.9 to
.0034 ppm) while that for crayfish from the cotton field area was 3.4 ppb
(range 3.0 to 4.0). The small difference presumably results from selective
pressure due to environmental exposure rather than true resistance to
methyl parathion.
.Field studies - The Federal Water Pollution Control Administration's
publication Water Quality Criteria (1968) 3/ lists the 48-hr TLm values
of methyl parathion to the water flea (Daphnia magna) as 4.8 ug/liter
(.0048 ppm).
If Eisler, R., "Acute Toxicities of Insecticides to Marine Decapod Crus-
taceans," Crustaceana, 16(3):302-310 (1969).
2/ Albaugh, D. W., "Insecticide Tolerances of Two Crayfish Populations
(Procambarus acutus) in South-Central Texas," Bull. Environ.
Contain. Tpxicol., 8(6):334-338 (1972).
3/ Federal Water Pollution Control Administration, "Water Quality
Criteria," Report of the National Tectenfreal Advisory Committee,
p. 37 (1968).
93
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Table 16. ACUTE TOXICITY - AQUATIC INVERTEBRATES
Fish*/
Exposure Toxicity effect
time (hr) calculated by
Toxicity level
measured by
(ppm)
References
Red crayfish
Red crayfish
Red crayfish
Sand shrimp
Grass shrimp
Hermit crab
Freshwater
shrimp
Daphnia magna
White River Crayfish
Procambarus acutus
24
48
72
96
96
96
*
24
48
96
48
n.
TI^
TLm
LC50
LC50
LC50
LDso
TLm
LC50
LC50
0.05
0.04
0.04
0.002
0.003
0.007
0.011
0.0048
0.003
0.0024 and
0.0034
b/
w
b/
c/
£/
£./
d/
e/
f/
sJ
al Common and scientific names of aquatic species other than fish:
Hermit crab
Blue crab
Brown shrimp
Freshwater shrimp
Water flea
White river crayfish
(not given)
Pagurus longicarpus
Callinectes sapidus
Penaeus aztecus
Palaemonetes kadiakensis
Daphaia magna
Procambarus acutus
b/ Muncy and Oliver, op. cit. (1963).
cj Eisler, op. cit. (1969).
d/ Naqvi, S.M., and D.E. Ferguson, "Levels of Insecticide Resistance in
Freshwater Shrimp, Palaemonetes kadiakensis," Trans. Am. Fish. Soc.,
99:696-699 (1970).
e/ Federal Water Pollution Control Administration, Water Quality Criteria.
Report of the National Technical Advisory Committee, p. 37 (1968).
f_/ Carter, F.L., and J.B. Graves, "Measuring Effects of Insecticides on
Aquatic Animals," LA Agr.. 16(2):14-15 (1973).
£/ Albaugh, D.W., "Insecticide Tolerances of Two Crayfish Populations
acutus) in South-Central Texas," Bull. Environ.
Contain. Toxicol., 8 (6): 334-338 (1972).
94
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A study of the acute (5 day) toxicity of methyl parathion to Louisiana
red crawfish (Procambarus clarki) was performed by Hendrick and Everett
(1965). _!/ The 5-day median tolerance limit (TLm) was determined to be
< 10 ppt.
There is little information on the symptoms of methyl parathion
poisoning in aquatic animals other than fish. One report describes
some of the symptoms exhibited by clams when exposed to methyl para-
thion (Eisler, 1970b 2/). An excessive production of mucus will occur,
the siphons will be extended, there will be gaping valves and sluggish-
ness which can be determined by lack of response to mechanical stimula-
tion.
Carter and Graves (1973) 3/ (Table 16) studied the toxicity of
methyl parathion to White River crawfish, three species of fish (Table 14),
and bullfrog tadpoles. Bullfrog tadpoles had a 96 hr LC50 of 6.4 ppm.
Crawfish were most sensitive to methyl parathion and other pesticides
tested, while the bullfrog tadpoles were least sensitive. When LCgg's
were compared, methyl parathion was 2,033 times more toxic to crawfish
than to the tadpoles. Among the fish species tested, bluegill was the
most sensitive. The authors concluded that higher animals are less sen-
sitive to the insecticides tested than are lower forms, and that responses
vary by species.
Naqvi et al (1969)4_/ investigated the toxicity of methyl parathion
to four populations of the fresh-water shrimp (Palaemonetes kadiakensis).
Ten shrimp were placed in 3.79 liter glass jars. Three replicates were
made to obtain average mortality for 30 shrimp at each concentration
tested.
Of the fresh-water shrimp populations tested, three were from
areas of high pesticide usage. They were (1) a drainage ditch near
Hollandale, Mississippi; (2) a 0.5 acre pond near Belzini, Mississippi;
and (3) a 640 acre lake (Sky Lake), Mississippi.
These were compared to fresh-water shrimp from Bluff Lake on the
Noxubee National Wildlife Refuge. The 24-hr median lethal concentra-
tion (ppm) for the different populations are given below;
I/ Hendrick, R. D., and T. R. Everett, "Toxicity to the Louisiana Red
Crawfish of Some Pesticides Used in Rice Culture," J. Econ,
Entomol.. 58:958-961 (1965).
2/ Eisler, R., "Latent Effects of Insecticide Intoxication to Marine
Molluscs." Hydrobiologia, 36:345-352 (1970b).
3J Carter, F. L., and J. B. Graves, "Measuring Effects of Insecticides
on Aquatic Animals," LA Agr., 16(2):14-15 (1973).
4/ Naqvi, S. M., and D. E. Ferguson, "Levels of Insecticide Resistance
in Freshwater Shrimp, Palaemonetes kadiakensis," Trans. Am. Fish.
Soc., 99:696-699 (1970).
95
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Naqvi and Ferguson (1969) !/ collected tubificfd worms (Tubifex
tubifex) from an area of high pesticide use (Belzoni, Mississippi).
After separation from the bottom mud, they were exposed in tap water
for 72 hours to concentrations of 6 ppm methyl parathion. No mor-
talities occurred at this concentration.
The author suggested that animals (i.e. Tubifex) which are able
to tolerate and presumably store large body burdens of toxicants such
as methyl parathion may present a hazard to higher trophic levels.
Two of the three exposed population have higher median lethal
concentrations than the one relatively unexposed population (Bluff
Lake). One (Sky Lake) has a lower median lethal concentration. The
author concluded that generally resistance was absent or weak toward
organophosphorus insecticides as compared with organochlorine and
carbamate insecticides tested.
Bluff Lake Hollandale Belzoni Sky Lake
0.0037 0.0141 0.230 0.0025
Mulla et al. (1963) —' studied the toxicity of methyl parathion
and other insecticides to the tadpoles of the Western toad (Bufo boreas),
and Hammond's spadefoot toad (Scaphiopus hammondi). Methyl parathion
was applied to 1/16-acre field ponds at a volume of 8 gal/acre as an
aqueous spray prepared from an emulsion concentrate containing 7.5 Ib
Al/gal. At application rates of 0.1 and 0.4 Ib Al/acre, methyl parathion
caused no mortalities to the tadpoles on 24-hr exposure.
Cook and Conners (1963) —' studied the effects on the lake biota of
mosquito control applications of methyl parathion at the rate of 3 ppb
(0.003 ppm) to Clear Lake, Lake County, California, to control the
Clear Lake gnat (Chaoborus astictopus). In the summer of 1962, methyl
parathion was applied to the lake three times, once each in June, July,
and August. Open lake water was sampled for plankton by a standard
plankton tow net. In the laboratory, the plankton was identified,
usually to genus, and visual estimates were made as to the relative
frequency of each. Samples were then spun down in a clinical centrifuge
where the phytoplankton and zooplankton would separate due to their dif-
ferent densities. Benthic samples were taken by means of an Eckman
dredge. Bottom mud was sifted and the benthic fauna transferred to a
collecting jar and counted.
I/ Naqvi, S. M. and D. E. Ferguson. "Pesticide tolerances of selected
freshwater invertebrates", J. Miss. Acad. Sci., 14:121-127
(1969).
2/ Mulla, M. S., L. W. Isaak, and H. Axelrod, "Field Studies on the Effects
of Insecticides on Some Aquatic Wildlife Species," J. Econ. Entomol.t
56(2):184-188 (1963).
3/ Cook, S. F., Jr., and J. D. Conners, "The Short-Term Side Effects of the
Insecticidal Treatment of Clear Lake, Lake County, California, in 1962",
Ann. Entomol. Soc-. Am. » 56(6) :819-824 (1963).
96
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Because there was only one other year in which data were collected
pertaining to plankton and benthic organisms, it could not be determined
whether observed variations are within the normal range of variability
that could be expected under these environmental conditions. However,
there was an immediate decrease in zooplankton population following the
second and third treatments. The zooplankton also failed to exhibit the
population explosion which was evident during September and October the
previous year. During this period of lower-than-expected zooplankton
populations, there was a bloom of the phyloplankton species Anabaena.
It is not known whether further studies were done to clarify if
variations in the zooplankton populations were within the normal range
of population variation or were a result of the methyl parathion ap-
plications. Further study is needed on the effects of methyl parathion
on zooplankton, especially to Daphnia and Cyclops. The TLm reported
earlier (Fed. Water Poll. Adm., 1968) for Daphnia magna as .0048 ppm,
is close to the concentration applied (.003 ppm).
From the data previously collected on benthic organisms, especially
the midge Chaoborus, there seemed to be no significant change in benthic
populations.
No harmful effects to fish populations were observed. There was no
significant increase in mortality of adults or fry and no significant
depression of brain cholinesterase levels after applications of methyl
parathion occurred.
The authors conclude from the wealth of data acquired in this manner
that the methyl parathion treatments of Clear Lake had generally a minimal
influence on the biota of the lake, with the exception of the target in-
sect, the Clear Lake gnat, and perhaps species of the zooplankton.
Hendrick et al (1966)i/ studied the effect of methyl parathion on
the red crayfish (Procambarus^ clarki) in a flooded rice field at
Crowley, Louisiana, where the rearing of crayfish in rice fields is of
considerable commercial importance. Four replicate plots, 41 by 41
feet, were used. Each has separate drainage and is separated from
adjacent plots by an 18-inch levee and fence, which effectively restricts
the test plots. Alkalinity, ph, dissolved oxygen, and C02 were recorded
and showed no difference resulting from treatments in any sampling period.
Data on weight and length were taken eight times between August,15, 1963
and April 28, 1964. Ground operated spray equipment was used to deliver
4 gallons of methyl parathion solution per acre on August 23, 1963. This
delivered 0.25 Ib. methyl parathion per acre, which resulted in a cal-
culated concentration of more than 100 ppb in 6 acre-in of rice field water,
— Hendrick, R. D.,.T. R. Everett, and H. R.^Caffey. "Effects of some
insecticides on the survival, reproduction and growth of the Louisiana
red crawfish." J. Econ. Entomol. 59;188-192 (1966).
97
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No symptoms of acute toxicity were observed during the test period.
An analysis of the data showed no significant difference in either the
number or weight of crayfish harvested form treated and control plot.
The author concluded that applications of methyl parathion resulted in
no measurable effect on survival* growth, and reproduction of the red
crayfish at the rate tested.
Additional reports on the interactions between methyl parathion
and lower aquatic organisms were not found. The data that was reviewed
in this section indicates that the pattern of toxicity of methyl para-
thion to aquatic organisms is similar to that of parathion. Methyl
parathion appears to be extremely toxic to aquatic insects, toxic to
the lower aquatic fauna, and relatively nontoxic to the lower aquatic
flora. Methyl parathion is considerably less persistent than parathion
in lake, river and field waters. Thus, its effects on lower aquatic
organisms would be expected to be less prolonged than those that might
be caused by comparable rates of parathion.
Effects on Wildlife
Laboratory Studies - There are only a few references to studies on the
toxicity of methyl parathion to wildlife; these references relate only
the susceptibility of birds.
Toxicity (LDgg) of methyl parathion for redwing blackbirds and for
starlings was reported by Schafer (1972)i/ to be 10 mg/kg and 7.5 mg/kg,
respect ively .
Tucker and Crabtree (1970)2/ report U>5o' s for mallards and pheasants
to be 10.0 mg/kg (range 6.12 to 16.3) and 8.21 mg/kg (range 5.69 to 11.9)
of body weight, respectively.
In a study of comparative subacute dietary toxicities of pesticide
to birds, Heath et al. (1972)—' reported that (1) Japanese quail were
more susceptible to methyl parathion than bobwhite quail, (2) that both
quail species were more sensitive than pheasant and (3) that the mallard
I/ Schafer, E. W., "The Acute Oral Toxicity of 369 Pesticidal, Pharma-
ceutical and Other Chemicals to Wild Birds," Toxicol. Appl. Pharmacol.,
21:315-330 (1972).
2/ Tucker, R. K., and D. G. Crabtree, "Handbook of Toxicity of Pesti-
cides to Wildlife," U.S. Department of the Interior, Fish and Wild-
life Service, Denver Wildlife Research Center, Resource Publication
No. 84 (1970).
3/ Heath, R. G., J. W. Spann, E. F. Hill, and J. F. Kreitzer, "Compara-
tive Dietary Toxicities of Pesticides to Birds," Special Scien-
tific Report, Wildlife No. 152, Bureau of Sport Fisheries and
Wildlife (1972).
98
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duck was the least susceptible of all four species. The LC5Q values re-
ported in the study were:
LC5Q - ppm in feed
Japanese quail 46
Bobwhite quail 90
Pheasant 116
Mallard duck 682
Shellenberger et al. (1968)!/ found that egg production of Japanese quail
was inhibited. Hatchability was reduced by 60 ppm methyl parathion. This
was in contrast to parathion1s reduction of hatchability at 27 ppm.
Field Studies - Robel et al. (1972)—' reported on the effects of methyl
parathion and other insecticides on populations of wild rodents in Kansas,
based on observations made from 1965 to 1969. The study was conducted
on two sites in Ellis County, Kansas, in a newly created irrigation dis-
trict that had not been extensively cultivated or treated with insecti-
cides prior to 1965. No insecticidal residue were found in samples of
water, soil, plants, or animals collected from the study sites prior to
initiation of the study in 1965.
Methyl parathion was applied to one field (the second field served
as an untreated control) at recommended and commonly used rates of appli-
cation as follows: 0.38 Ib Al/acre in 1966; 0.5 in 1967; 0.53 in 1968.
Live rodents were trapped in the treated and control fields from 1965
through 1969. A total of 4,661 rodents were captured, of which 162 were
analyzed for residues.
No methyl parathion residues were found in any of these specimens.
The species composition of the trapped rodents was similar for the
treated and the untreated study area, as were the population levels of
Peromyscus maniculatus which comprised about 74% of the total rodent
population in the two areas. Average minimal longevity for P_.
maniculatus and monthly survival between June and September did not
differ significantly between the treated and the untreated areas. Thus,
none of the parameters observed in this study indicated any effects on
the wild rodent population from the use of methyl parathion at field
rates over a 3-year period.
I/ Shellenberger, T. E., J. B. Gough, and L. A. Escuriex, "Comparative
Toxicity Evaluation of Organophpsphate Pesticides with Wildlife,"
Ind. Med. Sure.. 37:537 (1968).
21 Robel, R. J., C. D. Stalling, M. E. Westfahl, and A. M. Kadoum,
"Effects of Insecticides on Populations of Rodents in Kansas -
1965-1969," Pest. Monit. J.. 6(2):115-121 (1972).
99
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Mclntyre and Causey (1971)— collected bobwhite quail in the field
in or very near to insecticide-treated soybean fields. Methyl parathion
was commonly applied to these fields along with other pesticides, but
no organophosphate residues were detected in the birds, while they showed
very high (average 17.08 ppm) residues of DDT.
Culley and Applegate (1967)2J determined insecticide residues in
representative species of reptiles, birds, and wild mammals from
Presidio, Texas. The Presidio Valley where this sampling was conducted
has approximately 384,000 acres of land, of which 2,900 acres are under
cultivation and pesticide treatments. The valley is at an elevation of
2,600 ft, surrounded by mountains in the United States and in Mexico
rising above 7,000 to 8,000 ft. The area represents a point source of
insecticide application within a large enclosed area.
Specimens of reptiles, birds, and mammals were obtained by shooting
or trapping from insecticide-exposed and nonexposed areas. All speci-
mens were kept frozen until processing and analysis. During 1965 when
this study was conducted, commercial growers used 15,900 Ib of methyl
parathion active ingredient on the cultivated acres in the valley.
Residues of methyl parathion were found in all environmental samples
analyzed, including lizard tail muscle, brain tissue, liver, coelom fat,
and stomach contents; sparrow breast muscle, brains, liver, and gizzards;
and in leg muscles and livers of pocket mice and kangaroo rats. Methyl
parathion residues generally ranged from 0.1 to 1.0 ppm; higher levels
were found in a few lizard tail muscles (4.4 and 4.9 ppm); in a few
samples of coelom fat of lizards (3.7 and 4.2 ppm); in lizard eggs
(11.6 ppm); in all samples of sparrow breast muscle (1.6 and 5.5 ppm);
in a few samples of sparrow brains (2.6, 2.8 and 3.2 ppm); and in some
samples of pocket mice and kangaroo rat leg muscles (2.9, 4.0 and 4.6
ppm). In general, the farther the specimens were collected from the
cotton fields, the less were the insecticide concentrations that they
carried.
About 2,000 Ib of parathion were used in the Presidio Valley in
1965, that is only about one-eighth of the quantity of methyl parathion
used. However, residues of parathion found in the same specimens were
in all instances very similar to those of methyl parathion, indicating
considerably greater environmental persistence of parathion as compared
to methyl parathion.
17 Mclntyre, S. C., Jr., and M. K. Causey, "Insecticide Residues in
Bobwhite Quail Associated with Alabama Soybean Production," J.
Alabama Acad. Sci., 42(1):28-33 (1971).
2j Culley, Dudley D., and Howard G. Applegate, "Insecticide Concentra-
tions in Wildlife at Presidio, Texas." Pest. Mpnit. J., 2:21-28
(1967).
100
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Applegate (1970)i/ collected samples of soil, vegetation, birds,
rodents, and lizards from a large area of the Big Bend National Park,
Texas, and analyzed them for insecticide residues. Samples were placed
in an ice chest as quickly as possible after collection, maintained under
refrigeration, and taken to Presidio, Texas, 3 to 5 days later where they
were placed in deep freezers and held for 10 to 14 days in frozen storage
until processing and analysis.M Methyl parathion residues were found in
six out of nine samples of surface soil, ranging from 0.01 to 6.34 ppm;
in four out of nine samples of leatherstem (Jatropha dioica), ranging
from 0.01 to 0.09 ppm; in 12 out of 20 samples of muscle tissue of rodents,
ranging from 0.01 to 3.23 ppm; in 9 out of 19 samples of whole lizards,
ranging from 0.01 to 0.70 ppm; and in 10 out of 19 samples of bird muscle,
ranging from 0.01 to 7.54 ppm.
There were no known direct applications of methyl parathion in the
park. The nearest areas using insecticides are all south of the park in
Mexico where methyl parathion and other pesticides are being routinely
applied to cotton fields. It is not known how the surprisingly high and
ubiquitous methyl parathion residues in the soil and in the different ani-
mal species sampled were acquired. Drift from cotton fields, use within
the park by campers or other visitors, and/or spillage in the course of
unauthorized movement across the border may be responsible.
The purpose of this study was to establish a baseline for further
investigations to show possible changes in the level of pesticide pollu-
tion of this park.
No other data was found on the toxicity of methyl parathion
under field conditions. The data on the oral acute toxicity of
methyl parathion to mallards and pheasants summarized by Tucker
and Crabtree (1970) indicates that methyl parathion is significantly
less toxic to these two species than its ethyl homolog, parathion.
2 /
The summary on parathion and methyl parathion by Pimentel (1971)—
includes one additional brief report on wildlife toxicity. In a U.S.
Department of Interior study (1966) ,3.7 methyl parathion was applied at
rates of 0.5 and 3.0 Ib Al/acre. Pheasant mortality was about 2% at
the lower rate, about 25% at the higher one.
i/ Applegate, H. G., "Insecticides in the Big Bend National Park,"
Pest. Monit. J.. 4(1):2-7 (1970).
!/ 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, D.C. (1971).
3_/ United States Department of the Interior, "Wildlife Research; Prob-
lems, Programs and Progress, Pesticide-Wildlife Relations," Fish
Wildlife Service, Bureau of Sport Fish. Wildlife Circular, No. 43,
117 pp. (1966).
101
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Methyl parathion labels carried the warning: "Poisonous to wildlife.
This product is toxic to wildlife. Birds and other wildlife in treated
areas may be killed."
Effects on Beneficial Insects
- The Handbook of Toxicology, Vol. Ill - Insecticides (Negherbon, 1959)i/
lists the LD5Q of methyl parathion by topical application to adult worker bees
(Apis mellifera) at 0.5 Ug/g. In comparable tests, parathion LDCQ'S were
determined at 0.147 ug/g in one test, 3.5 P-g/g in another.
2/
Johansen (1972)— investigated the toxicity of field-weathered resi-
dues of methyl parathion and other insecticides to different species of
bees. Methyl parathion from a 4-lb/gal emulsifiable liquid was applied
to alfalfa at the rate of 0.5 lb Al/acre. Three kinds of bees were
exposed to the methyl parathion residues 10 hr after application. Bee
mortality was determined after 24 hr and ranged from 48 to 89% (41 to
66% for parathion under the same conditions).
These data indicate that methyl parathion is highly toxic to bees,
and that its order of toxicity to this species is in the same range as
that of parathion. Methyl parathion labels state: "This product is
highly toxic to bees exposed to direct treatment or residues on crops."
Cooperative Agricultural Extension Service recommendations in many states
provide specific warnings and advice applicable to local conditions
intended to prevent bee damage from the use of methyl parathion.
There is little data available regarding the effects of methyl
parathion on parasites and predators.
One important report is that by Lingren et al. (1972)i/ who studied
the toxicity of methyl parathion and other insecticides to two species of
parasitic wasps, i.e., Apanteles marginiventris and Campoletis perdistinctus.
I/ Negherbon, William 0., "Insecticides," The Handbook of Toxicology,
Vol. Ill, Tech. Report No. 55-16, W. B. Saunders, Phil., Pa.
(1959).
2/ Johansen, C. A., "Toxicity of Field-Weathered Insecticide Residues
to Four Kinds of Bees," Environ. Entomol.. 1(3):393-394 (1972).
102
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The U>5o of methyl parathion to adult C. perdistinctus (topical application)
was 0.0004 ug/insect to males, 0.0025 ug/insect to females. In this test,
methyl parathion was six times more toxic to male £. perdistinctus than para-
thion; a comparable toxicity value of parathion for female £. perdistinctus
is not given. The 1^59 of methyl parathion to A. marginiventris (mixed
sexes) was 0.0004 ug/insect.
When the insecticides were applied topically to cocoons of the two
wasp species, methyl parathion produced 9% mortality of £. perdistinctus
cocoons at 0.04 ug/cocoon. In similar tests on A. marginiventris, methyl
parathion produced 37% cocoon mortality at 0.03 ug/cocoon.
Methyl parathion was also highly toxic to adult male £. perdistinctus
confined on caged cotton plants treated at 0.5 and 1.5 Ib Al/acre in the
field.
These data indicate and the field experiences of many cotton ento-
mologists confirm that methyl parathion at commercial use rates is highly
detrimental to wasps, as well as to other important parasites and
predators.
Interactions with Lower Terrestrial Organisms
Matsumura and Boush (1971)—' recently reviewed the metabolism of
insecticides by microorganisms. They point out that organophosphate
insecticides (including methyl parathion) have thus far apparently nei-
ther presented serious problems in soils as regards undesirable persis-
tence, nor demonstrated an extraordinary affinity for fat with resulting
concentration in food chains. Although considerable variation exists
between individual organophosphates, most of them are readily degraded
in soil, mainly by hydrolytic and oxidative means. A number of reports
are cited which show that specific microorganisms degrade one or more
organophosphates under laboratory conditions, but none of these publica-
tions deal specifically with methyl parathion.
^/ 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).
2J Matsumura, F., and G. M. Boush, "Metabolism of Insecticides by Micro-
organisms," Soil Biochemistry. 2:320-336, Marcel Dekker, New York
(1971).
103
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The authors point out that no one has yet demonstrated whether or
not such microbiological degradation actually occurs in nature, or even
that any of these pesticides serve as nutritional or energy sources for
organisms. "There are no reports as yet that these chemicals have been
shown to serve as sole nutritional carbon sources."
Several publications by Naumann (1970a, 1970b, 1970c, 1971)!lV deal
with the effects of methyl parathion on the soil microflora. Methyl para-
thion in the form of a wettable powder was mixed with loess black soil in
field and greenhouse tests continued over a 5-year period. Methyl para-
thion was found to cause a significant increase in the total content of
bacteria and actinomycetes at dosages 200 times higher than the concentra-
tion that would be obtained by normal field application. The bacterial
stimulation following application of methyl parathion was influenced by
soil temperature and humidity. Low soil temperature and low soil humid-
ity delayed the stimulation of the bacteria. At normal application
rates, the total bacterial population of the soil would be influenced
only slightly by methyl parathion.
Soil applications of methyl parathion at 550 ppm or greater initially
decreased the soil respiration rate as measured by the Warburg technique.
However, after a few hours, the oxygen consumption increased, surpassing
the respiration of untreated soil. Stimulation of oxygen consumption by
methyl parathion was greater in sand and compost soil than in loam soil.
In loam soil, the mineralization of glucose was increased by the addition
^/ Naumann, K., "The Dynamics of Soil Microflora Following the Applica-
tion of Plant Protection Agents. I. Field Experiments on the Effect
of Methyl Parathion on the Bacterial and Ray Fungi Population of
the Soil," Zentr. Bakteriol. Parasitenk.,. Abt. II: Naturw., 124(7):
743-754 (1970a).
21 Naumann, K., "The Dynamics of Soil Microflora Following the Applica-
tion of Plant Protection Agents. II. The Reaction of Various
Physiological Groups of Soil Bacteria to the Application of Methyl
Parathion in the Field," Zentr. Bakteriol. Parasitenk., Abt. II:
Naturw., 124(7):755-765 (1970b).
3/ Naumann, K., "The Dynamics of the Soil Microflora after Application
of Plant Protective Agents. IV. Investigations on the Effects of
Methyl Parathion on Respiration and Dehydrogenase Activity of the
Soil," Zentr. Bakteriol. Parasitenk.. Abt. II: Naturw., 125:119-133
(1970c).
4/ Naumann, K., "Changes in the Composition of the Soil Microflora Follow-
ing Application of Plant Protection Agents to the Soil," Zentr.
Bakteriol. Parasitenk. Infektionskr. Hyg.. Abt. II: 126(5):530-544
(1971).
104
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of methyl parathion. Repeated methyl parathion applications at high rates
showed that after the third application there was no further stimulation
of the oxygen consumption per hour. The author attributes this to reaching
the toxic limit. The dehydrogenase activity in loam soil treated with high
rates of methyl parathion was almost completely blocked.
The effects of methyl parathion on different types of soil bacteria
were studied in a 21-week test. Higher rates of methyl parathion showed
more marked effects on the ammonifying and nitrifying bacteria, and lesser
effects on cellulose-decomposing, anaerobic and spore-forming bacteria.
The methyl parathion treatments did not affect the denitrifying bacteria
or the soil algae significantly.
It appears that these effects of methyl parathion on different soil
microorganisms occurred only at concentrations many times higher than
those that would be encountered in normal insect control use.
Our search of the literature and of other sources failed to yield
any publications dealing with the effects of specific microorganisms on
the persistence of methyl parathion in the soil. However, there is
every reason to believe that the soil organisms shown by a number of
authors to degrade parathion will also degrade methyl parathion. Methyl
parathion, like parathion, appears to be subject to both chemical and
biological degradation in the soil.
Residues in Soil
Laboratory Studies - Baker and Applegate (1970).L/ determined the persis-
tence of methyl parathion (and other pesticides) in three alkaline soils
(Houston Black clay, Pima silty clay, and Final gravelly loam) in growth
chambers at two temperatures (30 and 50°C), with and without exposure to
biologically effective ultraviolet radiation. The pesticides were added
to 20-g soil samples in glass Petri dishes at 5, 20 and 1,000 ppm. Pesti-
cide residues were determined by gas chromatography at different intervals
after treatment. The Soxhlet extraction method employed recovered 95 to
99% of the added pesticide.
Soils treated with methyl parathion at 5 ppm lost 46 to 48% of the
initial quantity in 50 days at 30°C. Under radiation, additional losses
of 10 to 14% methyl parathion occurred. After 50 days at 50°, 64 to 65%
methyl parathion had disappeared; radiation increased the loss by 14 to 17%.
I/ Baker, R. D., and H. G. Applegate, "Effect of Temperature and Ultra-
violet Radiation on the Persistence of Methyl Parathion and DDT
in Soils," Agron. J.. 62(4):509-512 (1970).
105
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Losses after 60 days from soils treated with methyl parathion at
20 ppm were as follows: At 30°C, 51 to 68% without radiation, an addi-
tional 9 to 11% with radiation; at 50°C, 70 to 80% without radiation, an
additional 5 to 10% under radiation. At this treatment level (20 ppm),
the Houston Black clay retained more methyl parathion than the other two
soils.
The soils treated at 1,000 ppm were analyzed qualitatively for break-
down products, but none were found in the methyl parathion series.
Nayshteyn et al. (1973)i' studied the stability and decomposition of
methyl parathion and several other pesticides in artificially acidified
and alkalinized soils with pH ranges of 3 to 4.6 and 8.7 to 9.6. Methyl
parathion was applied at 2 and 200 mg/kg at a soil temperature of 18 to
20°C. Methyl parathion was more stable in the acidic soils, and it was
generally more stable than two other organic phosphates studied (not
including parathion). The authors report that the rate of decomposition
of all three organic phosphate insecticides was comparable in native and
in sterile soils. They concluded that the role of soil microorganisms
in the degradation of methyl parathion (and of the other two organophos-
phates) is of secondary importance compared to chemical hydrolysis..
King and McCarty (1968)^/ developed a chromotagraphic model for pre-
dicting pesticide migration in soils. For several insecticides including
methyl parathion, theoretical elution curves based on chromotagraphic
theory were developed and compared with experimental degradation and
leaching data. Four soil types (Hugo, Elkhorn, Sweeney, and Tierra) and
different column lengths and pesticide application rates were employed.
Methyl parathion was applied to the four soil types at application
rates ranging from 1.0 to 50.0 Ib Al/acre. Its half-life ranged from
3 to 11 days. In the Hugo and Elkhorn soils, the application rate did
not appreciably affect the half-life. In the Sweeney and Tierra soils,
the half-life at 1.0 Ib Al/acre was 3 and 5 days, respectively; at 10 Ib
Al/acre, it was 11 and 8 days, respectively. Parathion was also included
in this test series. Its half-life under the same conditions was gener-
ally two to four times longer than that of methyl parathion.
If Nayshteyn, S. Y., V. A. Zhulinskaya, and Y. M. Yurovskaya, "The Sta-
bility of Certain Phosphororganic Pesticides in the Soil," Gig.
Sanit., 38(7):42-45 (1973).
2/ King, P., and P. L. McCarty, "A Chromatographic Model for Predicting
Pesticide Migration in Soils," Soil Sci.. 106(4):248-261 (1968).
106
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Field and Combined Field-Laboratory Studies - Lichtenstein and Schulz
(1964)!/ applied methyl parathion at 5 Ib/acre to Carrington silt loam
field plots. Residue levels of methyl parathion of approximately 0.1
ppm (3.1% of the applied dosage) were reached under field conditions
within 30 days after the insecticidal application to the soil (90 days
in the case of methyl parathion).
Under laboratory conditions (30°C), 95% of an applied methyl para-
thion dose (200 ppm) was lost within 12 days after application to a loam
soil (only 30% of a comparable parathion dose was lost under the same
conditions) .
Baida (1970).?/ investigated the persistence of methyl parathion and
other organic phosphate pesticides in the soil in irrigated field plots
at the experimental station of the Kazak Institute of Plant Protection,
USSR. A cabbage crop was treated four to five times during the growing
season with the. insecticides and irrigated six to eight times. Methyl
parathion at the rate of 56 Ib Al/acre of a 2.5% dust was applied twice,
once in July and once in August. Soil samples were taken from the 0 to
4 in. and the 4 to 8 in. soil horizons 15, 30 and 60 days after the last
treatment. The results showed that the organophosphorus pesticides dis-
appeared rapidly from the soil which was high in organic matter content.
Methyl parathion was still detectable 2 weeks after the second treatment
of the cabbage, but residues had declined to nondetectable levels by 4
weeks. Leaching to lower soil horizons was insignificant with all insec-
ticides tested. The author concludes that the rapid disappearance of
methyl parathion and the other organic phosphates prevented their accumu-
lation and contamination of the soil.
Monitoring Studies - Stevens et al. (1970)2J reported on a pilot study
conducted 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 pesticide
use. This study was obviously aimed primarily at chlorinated hydrocarbon
I/ 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).
21 Baida, T. A., "Soil Pollution by Organophosphorus Pesticides,"
Zdravookhr. Kazakstana. 30(7):72 (1970).
3/ Stevens, L. J., C.. W. Collier, and Donald W. Woodham, "Monitoring
Pesticides in Soils From Areas of Regular, Limited, and No Pesti-
cide Use," Pest. Monit. J., 4(3):145-164 (1970).
107
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pesticides; only those.organophosphates that were amenable to chlorinated
pesticide clean-up methods were detected, and no concerted efforts were
made to quantitate metabolites or oxygen analogs of the organophosphates.
Pesticide use records indicated that methyl parathion had been used at a
number of the sites sampled, but the report does not include any single
detection of methyl parathion.
In the National Soils Monitoring Program for Pesticides, 1,729 samples
of cropland soils from 43 states were collected in 1969 (Wiersma et al.,
197217). Of these, 66 samples were analyzed for organic phosphate residues,
but not a single detection of methyl parathion was reported. In the same
program in 1969, 199 samples of noncropland soil were also obtained, but
none of these were analyzed for organophosphate residues.
In the National Soils, Monitoring Program for Pesticides in 1970
(Crockett et al., 1970.2/) , soil and crop samples were collected from
1,506 cropland sites in 35 states. Pesticide use records indicated that
methyl parathion had been used at 44 of 1,346 sites sampled, that is
3.27% of all sites. The mean application rate of methyl parathion was
4.16 Ib Al/acre. No analyses of soil samples for methyl parathion resi-
dues 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. Residues
of methyl parathion were found in 9 of 18 samples of cotton stalks and
green bolls, ranging from 0.13 to 6.20 ppm, mean 0.58 ppm; and in 7 of 37
samples of cotton seed, ranging from 0.01 to 0.08 ppm, mean 0.01 ppm. No
residues of methyl parathion were detected in any of the other commodities
analyzed.
Wiersma et al. (1972b)^./ monitored pesticide residues in commercially
grown onions and in the soil on which these onions were grown in 1969. A
total of 76 sites in 10 major onion-producing states were sampled. Accord-
ing to pesticide use records, methyl parathion was not used at all in any
of the onion fields sampled. However, methyl parathion residues were found
I/ Wiersma, G. B., H. Tai, and P. F. Sand, "Pesticide Residue Levels in
Soils, FY 1969 - National Soils Monitoring Program," Pest. Monit. J..
6(3): 194-228 (1972).
"LJ 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).
3/ Wiersma, G. B., W. B. Mitchell, and C. L. Stanford, "Pesticide Residues
in Onions and Soil - 1969," Pest. Monit. J.. 5(4):345-347 (1972).
108
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in 11.8% of the soil samples, ranging from 0.09 to 1.90 ppm, average 0.08
ppm. No residues of methyl parathion (or of any of the other pesticides)
were detected in onions. The origin of the methyl parathion residues in
the soil samples where it was detected is not clear.
There are limitations in National Soils Monitoring Program data. No
information is provided on the relationships between time of pesticide
application, time of sampling, and time of processing and analysis of the
samples. No data is available on the effects of shipping and storage of
the samples on the methyl parathion residues that may have been present
at the time of sampling.
The California Department of Water Resources (1969, 1970)!z2/ reported
pesticide concentrations determined in surface and subsurface drain efflu-
ents in the San Joaquin Valley. In 1969, 14 samples of surface drain efflu-
ents were analyzed for organophosphates. No methyl parathion was found in
any of these samples. Eight samples contained "unknown" organophosphate
residues that were not further identified. No methyl parathion residues
were identified in 41 samples of subsurface drain effluents analyzed for
organophosphates in the same year (1969). Organic phosphate "unknowns"
were found in 19 of these 41 samples, but no further identification was
made.
In 1970, 18 samples of surface drain effluents were analyzed for
organophosphate compounds. Methyl parathion was positively identified
in three of these, at concentrations ranging from 10 to 190 ppt (parts
per trillion), averaging 13 ppt in all samples analyzed, 72 ppt in the
positive samples. In the same year (1970), 60 samples of subsurface
drain effluents were analyzed for organophosphates. Methyl parathion
was detected in eight of these, at concentrations ranging from 10 to
170 ppt, averaging 29 ppt in all samples analyzed, 76 ppt in the posi-
tive samples.
These data show that only very small quantities of methyl parathion
(and of other organophosphate insecticides) were present in these effluents.
^/ California Department of Water Resources, San Joaquin Valley Drainage
Monitoring Program, 1969 Summary, Sacramento, California (1969).
(In: Li and Fleck, 1972.)
21 California Department of Water Resources, San Joaquin Valley Drainage
Monitoring Program, 1970 Summary, Sacramento, California (1970).
(In: Li and Fleck, 1972.)
109
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Summary - The data on the residues and fate of methyl parathion in the
soil reviewed in this section show that methyl parathion is generally
several times less persistent in the soil than parathion. Methyl para-
thion soil residues resulting from crop protection uses at recommended
dosage levels appear to be degraded in the soil very quickly.
As with parathion, the soil degradation of methyl parathion is prob-
ably temperature dependent. Data presented in next subsection of this
scientific review on "Use patterns of methyl parathion in the United.
States," show that only very small quantities of methyl parathion are
used in the Northeastern, North Central and Northwestern states of the
U.S. An estimated 98% of the total quantity of methyl parathion used
in the U.S. in 1972 was used in the Southeastern, South Central and
Southwestern states where higher temperatures would promote rapid degra-
dation of methyl parathion in the soil.
Soil monitoring data currently available are totally inadequate to
show whether or not these theoretical expectations are true. Likewise,
no data are available on the fate of the initial degradation products
of methyl parathion, especially £-nitrophenol and amino-methyl parathion,
or on the effects of these breakdown products on organisms other than
mammals and insects.
Residues in Water
Laboratory and Field Studies - Lichtenstein et al. (1966)^' studied the
persistence of methyl parathion and several other insecticides in lake
water and soil water over a 1-year period. Lake water was collected
from the surface and near the shore line of Lake Mendota, Madison,
Wisconsin, and soil water was obtained by percolating 3,000 ml of dis-
tilled water through a 45.0 by 7.5 cm column of Carrington silt loam
untreated with insecticides. Volumes of 1,200 ml of both types of water
were treated with methyl parathion at the rate of 1 ppm, using 10 ml of
acetone containing 1.2 mg of the insecticide. The water samples were
then kept at 28°C in darkness. They were bioassayed for toxicity to mos-
quito larvae, and subjected to chemical analysis at different intervals.
Methyl parathion in lake water produced 10% mortality of mosquito
larvae after 3 months, 07o after 4 months. In the soil water, methyl
parathion produced 10070 mosquito larvae mortality after 0.5 months, but
I/ Lichtenstein, E. P., K. R. Schulz, R. F. Skrentny, and Y. Tsukano,
"Toxicity and Fate of Insecticide Residues in Water," Arch. Environ.
Health, 12:199-212 (1966).
110
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was nontoxic to the mosquito larvae after 1 month. By gas chromatographic
analysis, no methyl parathion residues were detected in either water after
7 months. By bioassay as well as by chemical analysis, methyl parathion
was considerably less persistent in this test than parathion. Methyl para-
thion (as well as parathion) persisted longer in lake water than in soil
water.
Eichelberger and Lichtenberg (1971)i' investigated the persistence
of methyl parathion and a number of other common pesticides in raw river
water over an 8-week period. Aliquots of 10 ug/liter of methyl parathion
from a freshly prepared 0.1% solution in acetone were injected into sam-
ples of raw water from the Little Miami River, a relatively small stream
receiving domestic and industrial wastes and farm runoff. The spiked raw
river water was kept in the laboratory in closed glass containers at room
temperature, exposed to natural and artificial light. Only 80% of the
initial concentration of methyl parathion remained after 1 hr; 25% after
1 week; 10% after 2 weeks, 0% after 4 weeks. When methyl parathion was
added to distilled water in the same manner, it remained completly stable
for an observation period of 3 weeks.
With the use of thin layer chromatography, it was determined that
methyl parathion was hydrolyzed to p_-nitrophenol and dimethylthiophos-
phoric acid.
Under the same experimental conditions, parathion was about two to
three times more persistent than methyl parathion in the river water.
Hazeltine (1962)!/ reported that in lake water (Clear Lake, California)
methyl parathion degraded rapidly. After application of rates effective
for the control of the Clear Lake gnat, Chaoborus astictopus. 2.5 and 3.3
ppb, 50% degradation occurred in less than 2 days.
\J Eichelberger, J. W., and J. J. Lichtenberg, "Persistence of Pesticides
in River Water," Environ. Sci. Technol.. 5(6):541-544 (1971).
21 Hazeltine, W. E., "Safety of Wildlife is Important to Planners of
Gnat - Control Program," Agr. Chem.. pp. 12-14, 76 (1962).
Ill
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Residues in Air
There is little data available on the origin, presence and per-
sistence of methyl parathion residues in air.
Stanley et al. (1971)!/ conducted a pilot study to establish a system
for measuring the extent of atmospheric contamination of the air by pesti-
cides in nine localities throughout the United States. Samples were ana-
lyzed for 19 pesticides and metabolites, including methyl parathion. Methyl
parathion was found at three of the nine sampling locations, i.e., Dothan,
Alabama (rural), Orlando, Florida (rural), and Stoneville, Mississippi
(rural). At Dothan, nine of 90 samples contained detectable amounts of
methyl parathion, the maximum level found was 29.6 ng/m^ of air. At
Orlando, three of 99 samples contained methyl parathion; the maximum
level was 5.4 ng/m3. At Stoneville, 40 of 98 samples contained methyl
parathion; the maximum level was 129 ng/m3. Higher pesticide levels
were usually associated with pesticide spraying. The authors point out
that the levels of pesticide found in the ambient air were almost entirely
far below levels that might add significantly to the total human intake
of pesticides.
2 /
Tessari and Spencer (1971) —' analyzed air samples from human environ-
ments in the Greeley, Colorado, area for pesticide residues. Nylon chiffon
cloth screens were exposed to the indoor and outdoor air at the homes of
12 men (farmers and pesticide formulators) occupationally exposed to pesti-
cides. Over a period of 1 year, the screens were exposed to the atmosphere
in these environments for 5 days each month, after which residues were
extracted from them with suitable solvents and determined by gas chromato-
graphic analysis.
Methyl parathion was found in 13 of 52 indoor air samples from for-
mulators1 households. In the positive samples, methyl parathion residues
ranged from 0.04 to 9.40 ug/mz of filter; the mean was 1.04 ug/m^. In
samples of outdoor air near formulators1 households, methyl parathion was
found in three of 53 samples. In the positive samples, residues ranged
from 0.15 to 0.71 ug/m^; the mean was 0.35 ug/m^. No methyl parathion
residues were found in the indoor or outdoor air near farmers' households.
Parathion which was also included in this investigation was found in
a much higher percentage of the samples tested, generally at considerably
higher concentrations.
I/ Stanley, C. W., J. E. Barney, II, M. R. Helton, and A. R. Yobs,
"Measurement of Atmospheric Levels of Pesticides," Environ. Sci.
Technol., 5(5):430-435 (1971).
21 Tessari, J. D., and D. L. Spencer, "Air Sampling for Pesticides in
the Human Environment," J. Assoc. Offic. Anal. Chem., 54(6):1376-
1382 (1971).
112
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Adair et al. (1971)i/ studied the drift of methyl parathion following
aerial application of an emulsifiable concentrate formulation containing
4 Ib Al/gal applied either undiluted (TJLV), or diluted in water at a
volume of 2 gal/acre (LV). Both sprays were applied at the rate of 1.0
Ib Al/acre from an airplane flying at a height of 5 ft at 80 mph. Each
treatment was repeated three times. Insecticidal deposits were sampled
in the swath and downwind from it at various intervals down to 1/2
mile with filter paper sheets and oil-sensitive cards. Aerial drift was
studied in air samples taken at several locations downwind of the swath
with cascade impactors.
The ULV-applied methyl parathion spread over a wider swath and was
deposited on the ground sample sheets in higher concentrations downwind
from the swath than the LV applications. The cascade impactor studies
showed that the amount of airborne drift downwind at the 5 ft sampling
height was much greater from the ULV application than from the LV appli-
cations at the 100 and 330 ft sites, and slightly greater at the 660- to
2,640-ft sites. For all applications studied, the total amount of methyl
parathion recovered in the target area and within 2,640 ft downwind from
it represented about 40 to 50% of the amount applied. These data show
that a large share of the material applied in this manner may become
quickly airborne and possibly move permanently into the atmosphere with
very little material falling to the ground downwind.
The reports reviewed indicate that methyl parathion residues may
be present in the atmosphere. The material balance studies by Adair
et al. indicate that at least under the conditions of their study,
about one-half of the quantity of methyl parathion applied by air did
not impinge in the target area or within 2,640 ft downwind from it;
apparently the methyl parathion met an unknown fate and destination.
Residues in Nontarget Plants
In accordance with the work plan for this project, residues and metab-
olism of methyl parathion in food and feed commodities are not covered in
this subsection, but the subsection on chemistry.
With the exception of a report by Applegate (1970).i/ there were no
reports found on methyl parathion residues in nontarget plants. Applegate
sampled the leaves of leatherstern (Jatropha dioica), a wild plant in the
Big Bend National Park in Texas. Residues of methyl parathion were found
in four out of nine samples of leatherstem leaves analyzed, ranging from
0.01 to 0.09 ppm. These residues are considerably below those encountered
on target plants following insecticidal applications of parathion. However,
they were found in plants growing in a park not subject to insecticide
treatments.
I/ Adair, H. M., F. A. Harris, M. V. Kennedy, M. L. Laster, and E. D.
Threadgill, "Drift of Methyl Parathion Aerially Applied Low Volume
and Ultra Low Volume," J. Econ. Entomol;, 64(3):718-721 (1971).
2f Applegate, H. G., "Insecticides in the Big Bend National Park,"
Pest. Monit. J., 4(1):2-7 (1970).
113
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In a report on insecticide concentrations in wildlife at Presidio,
Texas, Culley and Applegate (1967) expressed the opinion that methyl para-
thion could accumulate in leatherstem because leaves of this perennial
plant had higher methyl parathion concentrations in June than did leaves
of cotton, an annual plant.
Bioaccumulation, Biomagnification
There was no data found specifically on the possible bioaccumulation
of methyl parathion. The physical, chemical, and biological properties
of methyl parathion make it unlikely that biomagnification in food chains
or food webs occurs, and there is no evidence that it does. Methyl
parathion is neither lipophilic or chemically stable, the two properties
whose combination produces the biomagnification phenomenon described for
chlorinated hydrocarbon insecticides and other chemicals. However,
Butler I/ has found 59- ppb methyl parathion in spotted seatrout, Cynoscion
nebulosus, ovaries collected near Arroyo City, Texas. Although measure-
ments of residues of the parent compound are necessary and of interest
environmentally, the insidious effects are probably the greatest threat
environmentally. It must be noted that organophosphates inhibit brain
cholinesterase in fishes at concentrations much lower than the short
term LCc.
Environmental Transport Mechanisms
Freed et al. (unpublished data quoted from von Rumker and Horay,
1972,2^) determined the propensity of methyl parathion for volatilization
and leaching under simulated field conditions for loam soils at 25°C at
an annual rainfall of 59 in. (150 cm). 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 studied in this manner may
or may not parallel a chemical's vapor pressure.
By this method, methyl parathion rated a volatilization index of
three, indicating an estimated median vapor loss from treated areas of
_!/ Butler, P.A., Data from U.S. Environmental Protection Agency, National
Estuarine Monitoring Program. (Unpublished).
2J von Rumker, R., and F. Horay, "Pesticide Manual," Department of State,
Agency for International Development, 1:173, 268 (1972).
114
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4.45 Ib/acre/year. This index number indicates a relatively high poten-
tial for volatilization of methyl parathion from traated soils, compared
to many other pesticides.
Leaching index numbers for pesticides indicate the approximate dis-
tance that the chemical would move through the standardized loam soil
profile under an annual rainfall of 59 in. (150 cm). Under these condi-
tions, methyl parathion rated a leaching index of two, indicating move-
ment of 4 to 8 in.
These volatilization and leaching index numbers for methyl parathion,
along with the laboratory and field observations reviewed above, indicate
that volatilization appears to be an important environmental transport
mechanism for this insecticide. Surface runoff in water or adsorbed on
solids may also occur, but methyl parathion is relatively unstable in the
presence of soil or field water. Leaching of methyl parathion through
soil profiles does not occur readily, and it is not likely that contami-
nation of subsoil or groundwater could occur from normal use because of
the relatively low leaching propensity, and the short persistence of
methyl parathion in the soil.
115
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References
Adair, H. M., F. A. Harris, M. V. Kennedy, M. L. Laster, and E. B.
Threadgill, "Drift of Methyl Parathion Aerially Applied Low Volume
and Ultra Low Volume," J. Econ. Entomol., 64(3):718-721 (1971).
Albaugh, D. W., "Insecticide Tolerances of Two Crayfish Populations
(Procambarus acutus) in South-Central Texas," Bull. Environ.
Contam. Toxicol.. 8(6):334-338 (1972).
Applegate, H. G., "Insecticides in the Big Bend National Park," Pest.
Monit. J., 4(1):2-7 (1970).
Baida, T. A., "Soil Pollution by Organophosphorus Pesticides,"
Zdravookhr. Kazakstana, 30(7):72 (1970).
Baker, R. D., and H. G. Applegate, "Effect of Temperature and Ultraviolet
Radiation on the Persistence of Methyl Parathion and DDT in Soils,"
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116
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121
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SUBPART II. D. PRODUCTION AND USE
CONTENTS
Page
-i
Registered Uses of Methyl Parathion 123
Federally Registered Uses 123
State Regulations 124
Production and Domestic 'Supply 143
Volume of Production 143
Imports 144
Exports 144
Domestic Supply 145
Formulations 145
Use Patterns of Methyl Parathion in the United States 146
General 146
Methyl Parathion Use Patterns by Regions 147
Methyl Parathion Use Patterns by Crops 149
Methyl Parathion Uses in California 149
Summary 151
References 173
122
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This section contains data on the production and uses of methyl
parathion. It is organized according to three subject areas: registered
uses, production and domestic supply, and use patterns. The section
summarizes rather than interprets scientific data reviewed.
Registered Uses of Methyl Parathion
Federally Registered Uses - Methyl parathion has a broad spectrum of
effectiveness against insects. Efficacy claims also include some
species of mites. Methyl parathion is registered and recommended in
the United States for use on a large number of crops, including impor-
tant field, forage and vegetable crops.
Tolerances for residues of methyl parathion have not been established,
but all residue tolerances established,for its ethyl homolog, parathion,
have been declared applicable to methyl parathion.
All registered uses of methyl parathion by crops, target pests, dos-
age rates, formulations, type of use, established tolerances, and use,
timing, and pre-harvest interval limitations are summarized in the EPA
Compendium of Registered Pesticides. III-D-41.1 through 41.40. It is
interesting to note that this 40-page section on methyl parathion is only
one-fourth as long as the comparable section on parathion, demonstrating
the fact that methyl parathion is registered and recommended for a much
smaller spectrum of crop protection and related uses than its ethyl
homolog.
The registered uses of methyl parathion are illustrated in the
following tables:
1. Table 17. Methyl parathion — Summary of registered uses of crops,
application rates, and rate and time restrictions.
2. Table 18. Pest — Insects and mites against which methyl parathion
is recommended (in alphabetical order by common names).
3. Tables 19 Registered uses of one of the common formulations
and 20. of methyl parathion, i.e., emulsifiable liquid
containing 4 Ib of AI per gallon, by crops; insects
and other pests controlled on each crop; recommended
dosage rates; and general specific directions
for, and limitations of use.
123
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Methyl parathion is also available to users in the form of emulsi-
fiable liquids containing 2.0, 3.2, and 4.25 Ib of AI per gallons;
in the form of a 2% liquid, and in the form of 70 and 80% technical
solutions. A few formulators offer methyl parathion dusts. There are
no methyl parathion pressurized sprays or granular formulations on the
market.
In addition to these formulations containing methyl parathion as
the only active ingredient, there are several formulations combining
it with other insecticides. For instance, a formulation containing
6 Ib of parathion and 3 Ib of methyl parathion AI per gallon is offered
by several major producers.
For most registered uses of methyl parathion, the rate of active
ingredient recommended per acre or per volume of spray for a given use
is the same, regardless of the type of formulation in which the product
is applied.
State Regulations - In many of the states that currently regulate the
use of pesticides, methyl parathion is subject to use restrictions.
For instance, in California, methyl parathion is one of 42 pesticides
that have been designated as "injurious or restricted materials." The
use of these pesticides is subject to special restrictions under regu-
lations administered by the California State Department of Agriculture.
A permit from the County Agricultural Commissioner must be obtained for
the use of methyl parathion. The product may not be applied in any
location where damage, illness or injury may result (from direct
application, drift, or residue) to persons, other crops, or animals
(including honeybees) other than the pest(s) which the application is
intended to destroy.
Before methyl parathion is applied, warning must be given to all
persons known to be on the property. After any formulation containing
methyl parathion has been applied at a rate greater than 1 Ib of active
ingredient per acre, adequate warning must be given to persons who enter
the treated property at the point or points of normal entry. The warning
notice must be readable at a distance of 25 ft.
124
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Table 17. METHYL PARATHION - SUMMARY OF REGISTERED USES BY CROPS, APPLICATION RATES
AND RATE AND TIME RESTRICTIONS
N>
Ol
Target crops
Agricultural crops
Alfalfa
Alfalfa (seed)
Almonds—'
Apples
Apricots
Artichokes
Barley
Beans (dry,
green and
lima
Beets
I/
Black eyed peas-
Broccoli
Brussels sprouts
Cabbage
Carrots
Cauliflower
Celery
Rate per
application
(Ib/AI)
0.23 - 1.25/acre
0.23 - 1.25/acre
0.12 - 1.0/100 gal
0.12 - 0.25/100 gal
0.5 - 1.0/acre
0.12 - 0.75/acre
0.46 - 1.0/acre
0.25
0.25
0.25
0.46
0.25
1.5/acre
1.5/acre
1.5/acre
1.0/acre
1.5/acre
Maximum
permissible
AI rate
(Ib/acre)
6.0
2.5
Minimum time, last
treatment to harvest (days)
15 day 0.23 thru 1.0/acre
15 day 0.23 thru 1.0/acre
20 day>1.0 thru 1.25/acre
14 day thru 6.0 Ib/acre
14 day thru 2.5 Ib/acre
7 day 0.5 thru 1.0/acre
0 day 0.12 thru 0.25/acre
15 day>0.25 thru 0.75/acre
15 day 0.5 thru 1.5/acre
15 day 0.5
21 day>0.50 thru 1.5 acre
15 day 0.46 thru 1.0/acre ,
21 day 0.46 thru 1.0/acre^-'
0.46 - 1.0/acre
7 day 0.
21 day>0
7 day 0.
21 day>0
10 day 0.
21 day> 0
15 day 0.
7 day 0.
21 day>0
15 day 0.
25 thru 0
.50 thru
25 thru 0
.50 thru
25 thru 0
.5 thru 1
46 thru 1
25 thru 0
.50 thru
46 thru 1
.5/acre
1.5/acre
.5/acre
1.5/acre
.5/acre
.5/acre
,0/acre
.5/acre
1.5/acre
.0/acre
-------
Table 17. (Continued)
Isj
ON
Target crops
Agricultural crops
(continued)
Cherries
Clover
Collards
Corn
Cotton
Cucumbers
Eggplant!./
Gooseberries
Grapes
Grass (hay and
pastures
Hops
Kale
Kohlrabi
Lettuce
Melons!/
Mustard greens
Nectarines-
Oats
Rate per
application
(Ib/AI)
0.125 - 25/100 gal
0.25 - 1.25/acre
0.5 - 1.5/acre
0.25/acre
0.12 - 3.0/acre
0.25/acre
0.12 - 0.25/acre
0.25 - 1.0/100 gal
0.75/acre
0.5 - 1.0/acre
0.25 - 1.5/acre
0.25 - 1.5/acre
0.46 - 1.0/acre
0.25 - 1.5/acre
0.12 - 0.75/acre
Maximum
permissible
AI rate
(Ib/acre)
2.5
0.75
Minimum time, last
treatment to harvest (days)
14 day thru 2.5 Ib/acre
15 day 0.25 thru 1.0/acre
20 day >1.0 thru 1.25/acre
10 day 0.5/acre *v
21 day >0.5 thru 1.5/acre
12 day 0.25/acre
7 day 0.12 thru 3.0/acre
15 day 0.25/acre
15 day 0.12 thru 0.25/acre
14 day thru 0.75 Ib/acre
15 day 0.75/acre
15 day 0.5 thru 1.0/acre
10 day 0.25 thru 0.5/acre
21 day >0.5 thru, 1.5/acre
7 day 0.25 thru 0.5/acre
21 day >0.5 thru 1.5/acre
21 day 0.46 thru 1.0/acre
7 day thru 2.0/acre
10 day 0.25 thru 0.5/acre
21 day >0.5 thru 1.5/acre
0 day thru 0.25/acre
15 day >0.25 thru 0.75/acre
-------
Table 17. (Continued)
Target crops
Agricultural crops
(continued)
Onions
Peaches
Peanuts
Pears
Peas
Peppers
Plums, prunes
Potatoes-,
Pumpkins-
Rice
Rutabagas
Rye
Safflower^'
Sorghum
Soybeans
Spinach
Squash—^
Strawberries
Sugar beets
Rate per
application
(Ib/AI)
0.25 - 0.87/acre
0.12 - 1.0/100 gal
0.375/acre
0.12 - 0.5/100 gal
0.46 - 1.0/acre
0.46 - 1.0/acre
0.12 - 1.0/100 gal
0.25 - 1.5/acre
0.25 - 0.75/acre
0.5 - 1.5/acre
0.12 - 0.75/acre
0.5/acre
0.5 - 1.0/acre
.0.25 - 1.0/acre
0.46 - 1.0/acre
0.5 - 0.75/acre
0.25 - 0.375/acre
Maximum
permissible
AI rate
(Ib/acre)
4.0
3.0
4.0
Minimum time, last
treatment to harvest (days)
15 day thru 0.87/acre
14 day thru 4.0/acre
15 day thru 0.375/acre
14 day thru 3.0/acre
10 day 0.46 thru 0.5/acre
15 diay >0.5 thru 1.0/acre
15 day thru 1.0/acre"
14 day thru 4.0/acre
5 day thru 1.5/acre
10 day thru 0.25/acre
15 day >0.25 thru 0.75/acre
7 day thru 0.5/acre
21 day >0.5 thru 1.5/acre
0 day 0.12 thru 0.25/acre
15 day >0.25 thru 0.75/acre
21 day 0.5 thru 1.0/acre
20 day 0.25 thru 1.0/acre
14 day 0.46 thru 0.5/acre
21 day >0.5 thru 1.0/acre
14 day 0.5 thru 0.75/acre
20 day 0.25 thru 0.375/acre
-------
Table 17. (Continued)
H
Ni
00
Target crops
Agricultural crops
(continued)
Sunflowers
Sweet potatoes
Tobacco
Tomatoes
Turnips
Vetch
Wheat
Ornamentals
Christmas tree
plantations (pine)
Forest, nonagricultural
and wastelands
Fine forests
Rate per
application
(Ib/AI)
Maximum
permissible
AI rate
(Ib/acre)
1.0/acre
0.75/acre
0.25 - 0.5/acre
0.12 - 1.5/acre
0.25 - 0.80/acre
0.25 - 1.25/acre
0.12 - 0.75/acre
0.I/acre
Minimum time, last
treatment to harvest (days)
30 day
15 day
15 day
10 day
15 day
7 day
15 day
15 day
20 day
0 day
15 day
None
thru 1.0/acre
thru 0.75/acre
0.188 thru 0.5/acre
0.12 thru 0.5/acre
>0.5 thru 1.5/acre
thru 0.25/acre
>0.25 thru 0.8/acre
0.25 thru 1.0/acre "
>1.0 thru 1.25/acre
thru 0.25/acre
?0.25 thru 0.75/acre
1.0/acre
None
I/ Use only in formulations with parathion.
2J 21-day preharvest interval thru 1.016/acre if tops are to be fed to livestock.
3/ Do not apply after flowering thru 0.5/acre.
Compiled from the EPA Compendium of Registered Pesticides, Vol. III.
-------
Table 18. PEST INSECTS AND MITES AGAINST WHICH METHYL PAEATHION
IS RECOMMENDED (IN ALPHABETICAL ORDER BY COMMON NAMES)
Common name
Alfalfa caterpillar
Alfalfa seed chalcid
Alfalfa weevil
*Aphids
Armyworm
Artichoke plume moth
Black grass bugs
Bean leaf beetle
Beet armyworm
Blister beetle
Boll weevil
Bollworms
Cabbage looper
Chinch bug
Clover leaf weevil
Clover seed chalcid
Coding moth
Corn earworm
Corn rootworm
Cotton leafperforator
Cotton leaf worm
Cowpea curculio
*Cutworms
European pine shoot moth
Egyptian alfalfa weevil
Fall armyworm
False chinch bug
Flea beetles
Fleahoppers
Grape leaffolder
Grass bugs
Grasshoppers
Green cloverworm
Green June beetle
Imported cabbage worm
Leafhoppers
Leaf miners
*Leafrollers
Lygus bugs
Mexican bean beetle
Mites
Mosquitoes
Nantucket pine tip moth
Oriental fruit moth
Peachtree borer
Scientific name
Colias eurytheme
Bruchophagus roddi
Hypera postica
Family Aphididae
Pseudaletia unpuncta
Platyptilia carduidactyla
Family Miridue
Cerotoma trifurcata
Spodoptera exigue
Family Meloidae
Anthonomus grandis
Heliothus spp.
Trichoplusia ni
Blissus leucopterus
Hypera punctata
Bruchophagus platypera
Laspeyresia pomonella
Heliothis zea
Diabrotica spp.
Bucculatrix thurberiella
Alabama argillacea
Chalcodermus aeneus
Family Noctuidae
Rhyacionia buoliana
Hypera brunneipennis
Spodoptera frugiperda
Family Lygaeidae
Family Chrysomelidae
Family Miridae
Demsia funeralis
Family Miridae
Family Acrididae
Plathyaena scabra
Cotinis nitida
Pieris rapae
Family Cicadellidae
Class Insecta
Class Insecta
Lygus sp.
Epilachna varivestis
Order Acarina
Family Culicidae
Rhyacionia frustrana
Grapholitha molesta
Sanninoidea exitiosa
129
-------
Table 18. (Continued)
Common name
Plant bugs
Plum cureulio
Potato psyllid
Rice leafminer (Calif, only)
Saltmarsh caterpillar
*Scales
Seedcom maggot
Sorghum midge
Stink bugs
Sunflower moth
Tadpole shrimp (Calif, only)
Threecolored alfalfa hopper
*Thrips
Velvetbean caterpillar
Vetch bruchid
*Webworms
Yellow striped armyworm
Scientific name
Family Miridae
Conotrachelus nenuphar
Paratrioza cockerelli
Hydrellia griseola
Estigmene acrea
Family Coccoidae
Hylemya platura
Contarinia sorghicola
Family Pentatomidae
Homoeosoma electellum
Order Notostraca
Spissistilus festinus
Order Thysanop tera
Anticarsia gemmatalis
Bruchus brachialis
Order Lipdoptera
Spodoptera ornithogalli
For specific pests see EPA Compendium of Registered Pesticides,
Volume III.
130
-------
Table 19. REGISTERED USES OF METHYL PARATHION EMULSIFIABLE LIQUID
(4 LB ACTIVE INGREDIENT PER GALLON) - CROPS AND OTHER USES,
PESTS, DOSAGE RATES AND USE LIMITATIONS^/
INSECTICIDE BY
Monsanto.
Emulsifiable insecticide for
controlling certain insects
on the listed field, forage,
fruit and vegetable crops.
NOT FOR HOME USE
Complete Directions for Use
USDA Reg. No. 524-128
Use only according to these label instructions.
READ "LIMIT OF WARRANTY AND LIABILITY" BE-
FORE BUYING OR USING. IF TERMS ARE NOT
ACCEPTABLE RETURN AT ONCE UNOPENED.
RESEALABLE BAG
tPull flaps apart to open.
Press along ridge to close.
Keep out of reach of children.
DANGER! fcPOISON^
See antidote statement and other required warning
statements on pages 6,7 and 8.
POISONOUS BY SKIN CONTACT, INHALATION, OR
SWALLOWING.
RAPIDLY ABSORBED THROUGH SKIN.
REPEATED EXPOSURE MAY, WITHOUT SYMPTOMS,
BE INCREASINGLY HAZARDOUS.
Do not get on skin, in eyes, on clothing.
Do not breathe dust vapor, or spray mist
Do not store near food or feed products.
Do not use or store near heat or open flame.
In case of fire, use water spray, foam, dry chemical
orCOi.
ACTIVE INGREDIENTS:
*0,0-dimethyl 0-p-nitrophenyl
phosphorothioate 45.3%
Aromatic petroleum derivative solvent . 48.0%
INERT INGREDIENTS: 6.7%
100.0%
•Equivalent to 4.0 Ibs. of 100%
methyl parathion per gallon.
Hazards and Ingredients
a/ Sample label of Monsanto Company, St. Louis, Mo.
EPA Registration No. 524-128.
This formulation is not currently marketed by Monsanto, but
the label is being made available to Monsanto's formulator
customers for methyl parathion technical (Personal
Communication, May 10, 1974).
131
-------
Table 19. (Continued)
limit of Warranty and Liability
Hazards and Safeguards
LIMIT OF WARRANTY AND LIABILITY
Monsanto Company warrants that this material con-
forms to the chemical description on the label and
is reasonably fit for the purposes referred to in the
directions for use. This product is sold subject to
the understanding that the buyer assumes all risks
of use or handling which may result in loss or dam-
age which are beyond the control of the seller, such
as for example incompatibility with other products,
the manner of its use or application, or the presence
of other products or materials in or on the soil or
crop. MONSANTO MAKES NO OTHER EXPRESS OR
IMPLIED WARRANTY OF FITNESS OR MERCHANT-
ABILITY. The'exclusive remedy of the user or buyer,
and the limit of the liability of Monsanto Company
or any other seller for any and all losses, injuries or
damages resulting from the use or handling of this
product shall be the purchase price paid by the user
or buyer for the quantity of this product involved.
The buyer and all users are deemed to have accepted
the terms of this notice which may not be varied by
any verbal or written agreement
ATTENTION
Do not use in any manner other than recommended
on this label.
To avoid excessive residues of methyl parathion
on food or forage crops, always observe the state-
ments found under "Directions for Use," limiting
the time before harvest when methyl parathion may
be applied.
POISONOUS TO WILDLIFE
This product is toxic to wildlife. Birds and other
wildlife in treated areas may be killed. Keep out of
any body of water. Do not apply when weather
conditions favor drift from treated areas. Do not
apply where runoff is likely to occur. Do not con-
taminate water by cleaning equipment or disposal
of wastes.
Combustible: Do not store or use near heat or open
flame. In case of fire, use water spray, foam, dry
chemical or CCh.
Keep out of reach of children.
DANGER!
POISONOUS BY SKIN CONTACT,
INHALATION, OR SWALLOWING.
RAPIDLY ABSORBED THROUGH
SKIN.
REPEATED EXPOSURE MAY,
WITHOUT SYMPTOMS, BE IN-
CREASINGLY HAZARDOUS.
DO NOT GET ON SKIN, IN EYES, ON CLOTHING:
Wear heavy natural rubber gloves and goggles. Wear
clean waterproof or freshly-laundered protective
clothing (coveralls, rubber boots, cap, etc.). Destroy
and replace gloves frequently.
Wash thoroughly with soap and warm water before
eating or smoking.
Bathe immediately after work and change all cloth-
ing. Wash clothing thoroughly with soap and hot
water before re-use.
In case of contact immediately remove contamin-
ated clothing and wash skin thoroughly with soap
and water; for eyes, flush with water for 15 minutes.
DO NOT BREATHE DUST, VAPOR, OR SPRAY MIST:
Wear a mask or respirator of a type passed by the
VS. Department of Agriculture for METHYL PARA-
THION protection. Airplane pilots should wear full-
face canister-type mask.
If handled indoors, provide mechanical exhaust
ventilation.
Do not apply or allow drift to areas occupied by
unprotected humans or beneficial animals.
DO NOT STORE NEAR FOOD OR FEED PRODUCTS:
Keep out of reach of children and domestic animals.
Not for use or storage in or around the home.
Bury spillage; clean up area with strong lye solution.
POISON
ATROPINE IS AN ANTIDOTE.
CONSULT PHYSICIAN FOR
EMERGENCY SUPPLY.
FIRST AID
CALL A PHYSICIAN AT ONCE IN ALL CASES OF
SUSPECTED METHYL PARATHION POISONING.
If symptoms or signs of poisoning include blurred
vision, abdominal cramps, and tightness in the chest
do not wait for a doctor but give two atropine tablets
(each 1/100 grain or 0.65 milligrams) at once. (One
tablet to children under five years of age.)
Safeguards and First Aid _ 7
132
-------
Table 19. (Continued)
First Aid and Antidote
8
Move patient immediately from the area where
methyl parathion is present.
Remove contaminated clothing and wash the skin
clean with plenty of soap and water to remove all
traces of methyl parathion. If swallowed, induce
vomiting by giving salty or soapy warm water. Have
victim lie down and keep quiet.
NEVER GIVE ANYTHING BY MOUTH TO AN
UNCONSCIOUS PERSON.
PHYSICIANS NOTE: This product is a cholinesterase
inhibitor. Warning symptoms include weakness,
headache, tightness in the chest blurred vision,
non-reactive pin-point pupils, salivation, sweating,
nausea, vomiting, diarrhea, and abdominal cramps.
TREATMENT: Large doses of atropine are required.
For adults, give 2.0 mg. to 4.0 mg. of atropine, pref-
erably by intravenous injection, at once and repeat
every 10 to 15 minutes until pupils dilate. In addition
to atropine, if 2-PAM Chloride (pralidoximechloride)
is available, administer according to manufacturer's
directions. Never give morphine. Clear chest by
postural drainage. Artificial respiration or oxygen
administration may be necessary. Observe patient
continuously 48 hours. Repeated exposure to
cholinesterase inhibitors may, without warning,
cause prolonged susceptibility to very small doses
of any cholinesterase inhibitor. Allow no further
exposure until time for cholinesterase regeneration
has been allowed as determined by blood tests.
TO PREVENT PERSONAL INJURY AND POSSIBLE
FATALITIES:
Keep all persons and animals out of treated areas
for 48 hours.
Vacated areas should not be re-entered until drifting
insecticide and volatile residues have dissipated.
Because this material is poisonous by skin contact,
inhalation or swallowing it should not be used in
such a manner or under weather conditions as will
permit drift of the spray onto areas not intended
to be sprayed.
This product is highly toxic to bees exposed to direct
treatment or residues on crops. Protective informa-
tion may be obtained from your Cooperative Agri-
cultural Extension Service.
DISPOSAL OF EMPTY CONTAINER-Do not re-use
this container. Completely empty the contents and
bury the unused chemical at least 18 inches deep
in an isolated location away from water supplies.
Rinse out the inside of the container with water to
which has been added detergent and caustic soda.
Carefully discard the rinse solution by burying at
least 18 inches deep in an isolated area away from
water supplies. Puncture and crush empty metal
container and bury at least 18 inches deep in a
supervised public or private dump.
Directions for Use
10
DIRECTIONS FOR USE
Be sure to read the precautionary statements before
using!
This product is designed for application after dilu-
tion with water and for use by trained operators
using airplane or power ground equipment. The
hazards and precautions for handling the product in
this container are equally applicable to it after dilu-
tion with water for spray application. Add the con-
centrate to the spray tank while filling with water,
and mix thoroughly either by means of a tank agi-
tator or pump by-pass. For best results, thoroughly
cover all surfaces to be treated with spray. Rates of
application given below should not be exceeded.
Never apply later than indicated to assure residue
levels it harvest are below tolerances established
by the Food and Drug Administration.
Consult the State Agricultural Extension Service or
Experiment Station for specific recommendations
regarding application, dosage and timing of sprays.
For application by ground equipment, add the de-
sired amount of concentrate to sufficient water to
apply at least 3 gallons of water per acre. For appli-
cation by aircraft, add the amount of concentrate
desired per acre to % to 3 gallons of water con-
sistent with crop growth and good coverage. Greater
quantities of water may be required to give sufficient
coverage of orchard trees.
Prevent Injury and Container Disposal
133
-------
Table 19. (Continued)
CEREAL
BARLEY, OATS, RYE AND WHEAT-For barley thrips.
use H to K pint per acre. For aphids, armyworms
up to third instar. leafhoppers and winter grain
mites, use % to 1H pints per acre. For climbing
cutworms use % to 1 pint per acre. For chinch bugs,
false chinch bugs and Say's plant bugs, use 1H pints
per acre. For western or brown wheat mites, use 1
pint per acre. Do not use more than % pint per acre
within 15 days of harvest.
CORN—For control of armyworms up to third instar.
climbing cutworms, com leaf aphids, com rootworm
adults, fall armyworms and stink bugs, use % pint
per acre. Do not apply within 12 days of harvest.
RICE—For rice stink bugs, use % to 1 pint per acre.
Do not apply within 15 days of harvest Shrimp,
crabs and crayfish may be killed. Do not apply where
these are important resources.
SORGHUM—For com leaf aphids and mites, use 1
pint per acre. For sorghum midges, use 1 pint to
1 quart per acre, 2 applications, 3 to 5 days apart
when approximately 90% of the heads have com-
pletely emerged from the boot or not later than start
of blooming. Do not apply closer than 21 days before
harvest Leaf injury may occur on some hybrid va-
rieties of sorghum. Spray a few rows a week or so
before booting to test effects upon plants.
GRASS (Forage)—For control of armyworms up to
third instar, crested wheat bugs, false chinch bugs,
grasshoppers and leafhoppers, use 1W pints per
acre. Do not apply within 15 days of harvest or
grazing.
HOPS—For control of aphids and spider mites, use
1 quart per acre. Do not treat closer than 15 days
before harvest
SOYBEANS—For control of climbing cutworms and
three-cornered alfafa hoppers, use ft pint per acre.
For control of garden webworms, use H to 1 pint
per acre. For control of aphids, blister beetles, Mexi-
can bean beetles, stink bugs, two-spotted mites and
velvet bean caterpillars, use 1 pint per acre. For
bollworms. cabbage loopers, fall armyworms up to
third instar, and green cloverworms, use 1 quart per
acre. Do not apply closer than 20 days before har-
vest or grazing.
SUGAR BEETS—For aphids, armyworms up to third
instar, flea beetles, leafhoppers, Lygus bugs, stink
bugs and webworms, use % pint per acre. Do not
treat closer than 20 days before harvest, 60 days if
tops are to be fed to livestock.
TOBACCO—For control of green peach aphids, use
H pint per acre. For control of surface feeding or
climbing cutworms, use % to 1 pint per acre.
CAUTION—When necessary to enter treated tobacco
fields within 24 hours after application, protective
clothing should be worn. Do not apply within 5 days
of priming tobacco or within 15 days of cutting
tobacco. Avoid contact with plant juices when prim-
ing or cutting tobacco.
Cereal Insects
11
Reid and Forage Insects cont'd.
13
Field and Forage Insects
12
FIELD AND FORAGE CROPS
ALFALFA AND CLOVER-For control of alfalfa weevil
larvae, aphids (including spotted alfalfa aphids) and
climbing cutworms, use V> to 1 pint per acre. For
alfalfa caterpillars, alfalfa adult weevils, armyworms
up to third instar, clover leaf weevils and webworms,
use 1 pint per acre. For Egyptian alfalfa weevils,
leafhoppers, Lygus bugs and spider mites, use 1 to 2
pints per acre. Do not treat closer than 15 days
before harvest, cutting, or grazing. In California and
Nevada do not use more than V pint per acre.
COTTON—For control of thrips, use % to % pint per
acre. For cotton leafworms, use % to K pint per
acre. For grasshoppers and fall armyworms up to
third instar, use Vi pint per acre. For spider mites
(does not control all species), use M to H pint per
acre. For control of fleahoppers, Lygus and other
minds, use K pint to 1 quart per acre. For boll
weevils, aphids and garden webworms, use K to 1
pint per acre. For false chinch bugs, use 1 pint per
acre. For cabbage loopers and cutworms, use 1 to 2
pints per acre. For bollworms, salt-marsh caterpil-
lars, armyworms up to third instar, cotton leaf
perforators and stink bugs, use 1 quart per acre.
Applications should be made at 4 to 5 day intervals
until control is obtained. At above dosages, appli-
cation may be made up to the day before harvest,
if harvest will be with mechanical pickers.
CAUTION—When necessary to enter treated cotton
fields within 24 hours after application, protective
clothing should be worn Do not apply within 5 days
of handpicking cotton.
Field, Forage and Fruit Insects
14
VETCH—For control of aphids, armyworms up to
third instar, climbing cutworms, leafhoppers, Lygus
bugs, spider mites and vetch bruchids, use 1 to 2
pints per acre. Do not treat closer than 15 days
before harvest or grazing.
FRUIT
APPLY AT THE RATES INDICATED FOR THE
FOLLOWING CROPS. MAKE NO APPLICATION
CLOSER THAN 14 DAYS BEFORE HARVEST.
APPLY AS FREQUENTLY AS NEEDED TO
CONTROL INSECTS.
APPLES—For control of aphids, codling moths, plum
curculjo, scales and red-banded leaf rollers, use H
pint to 1 quart per 100 gallons of water. For codling
moths, plum curculio and red-banded leaf rollers,
apply at petal fall and 3 to 4 applications, 8 to 14
days thereafter, to maintain control. Do not use
more than 6 quarts of this product per acre.
GRAPES—For control of aphids, grape leaf folders
and grape leafhoppers, use W pint to 1 quart per
100 gallons of water. Do not use more than Hi
pints of this product per acre.
134
-------
Table 19. (Continued)
PEACHES, PLUMS AND PRUNES-For control ot
aphids, peach tree borers, plum curculio and Orien-
tal (ruit moths, use K pint to 1 quart per 100 gallons
of water. Spray tree trunks at time of moth flight to
conrol peach tree borers. For plum curculio and
Oriental fruit moths, apply at petal fall or shuck
split and 3 to 4 applications. 8 to 14 days thereafter,
to maintain control. Do not use more than 1 gallon
of this product per acre.
STRAWBERRIES-For control of aphids, use 1 to IV,
pints per acre.
OIL SEED CROPS
SAFFLOWER—For aphids and Lygus bugs, use 1
pint per acre before flowering. Do not apply after
flowering.
SUNFLOWER—For control of sunflower moth, use
1 quart per acre. Make no more than 3 applications
at 5-day intervals. Do not apply within 30 days of
harvest
BRUSSELS SPROUTS—For control of aphids, army-
worms up to third instar, flea beetles, leafhoppers
and mites, use 1 to 3 pints per acre. For cabbage
loopers and stink bugs, use 2 to 3 pints per acre.
Rates above 1 pint should not be applied closer than
21 days before harvest.
CAULIFLOWER—For control of aphids, armyworms
up to third instar, flea beetles, leafhoppers and
mites, use 1 to 3 pints per acre. For cabbage loopers
and stink bugs, use 2 to 3 pints per acre. Rates above
1 pint should not be applied closer than 21 days
before harvest.
KOHLRABI—For control of aphids, armyworms up to
third instar, flea beetles, leafhoppers and mites, use
1 to 3 pints per acre. For cabbage loopers and stink
bugs, use 2 to 3 pints per acre. Rates above 1 pint
should not be applied closer than 21 days before
harvest.
RUTABAGAS—For control of aphids, armyworms up
to third instar, flea beetles, leafhoppers and mites,
use 1 to 3 pints per acre. For cabbage loopers, use
2 to 3 pints per acre. Rates above 1 pint should not
be applied closer than 21 days before harvest.
Fruit and Oil Seed Insects
15
Vegetable Insects cont'd.
17
Vegetable Insects
16
Vegetable Insects conf d.
18
VEGETABLES
APPLY AT THE RATES INDICATED FOR THE
FOLLOWING CROPS. MAKE NO APPLICATIONS
CLOSER THAN 5 DAYS BEFORE HARVEST.
POTATOES—For control of aphids, armyworms up
to third instar, cabbage loopers, false chinch bugs,
flea beetles, leafhoppers. mites and shield bugs,
use IK quarts per acre.
SWEET POTATOES—For control of aphids, army-
worms up to third instar, surface feeding and climb-
ing cutworms, flea beetles, leafhoppers and mites,
use V quart per acre.
APPLY AT THE RATES INDICATED FOR THE
FOLLOWING CROPS. MAKE NO APPLICATIONS
CLOSER THAN 7 DAYS BEFORE HARVEST.
ARTICHOKE—For control of aphids, armyworms up
to third instar, surface feeding and climbing cut-
worms, flea beetles, leafhoppers, mites and artichoke
plume moths, use 1 quart per acre.
BROCCOLI—For control of aphids, armyworms up to
third instar, flea beetles, leafhoppers and mites, use
1 to 3 pints per acre. For cabbage loopers and stink
bugs, use 2 to 3 pints per acre. Rates above 1 pint
should not be applied closer than 21 days before
harvest
APPLY AT THE RATES INDICATED FOR THE
FOLLOWING CROPS. MAKE NO APPLICATIONS
CLOSER THAN 10 DAYS BEFORE HARVEST.
CABBAGE—For control of aphids, armyworms up to
third instar, tlea beetles, leafhoppers and mites, use
1 to 3 pints per acre. For cabbage loopers and stink
bugs, use 2 to 3 pints per acre. Rates above 1 pint
should not be applied closer than 21 days before
harvest
COUARDS, KALE AND MUSTARD-For control of
aphids, armyworms up to third instar, flea beetles,
leafhoppers and mites, use 1 to 3 pints per acre.
For cabbage loopers and stink bugs, use 2 to 3
pints per acre. Rates above 1 pint should not be
applied closer than 21 days before harvest
PEAS—For control of aphids, armyworms up to
third instar, flea beetles, leafhoppers, Lygus bugs
and mites, use 1 to 2 pints per acre. For cabbage
loopers, cowpea curculio, surface feeding and climb-
ing cutworms and stink bugs, use 2 pints per acre.
Rates above 1 pint should not be applied closer than
15 days before harvest
TOMATOES—For control of aphids, armyworms up
to third instar, flea beetles, leafhoppers, mites and
psyllids, use 1 to 3 pints per acre. For cabbage loop-
ers, use 2 to 3 pints per acre. Rates above 1 pint
should not be applied closer than 15 days before
harvest
135
-------
Table 19. (Continued)
APPLY AT THE RATES INDICATED FOR THE
FOLLOWING CROPS. MAKE NO APPLICATIONS
CLOSER THAN 15 DAYS BEFORE HARVEST.
BEANS (Dry and Green)—For control of aphids,
armyworms up to third instar, flea beetles, leafhop-
pers, Lygus bugs and mites, use 1 to 3 pints per
acre. For cowpea curculio, surface feeding and climb-
ing cutworms and stink bugs, use 2 to 3 pints per
acre. Rates above 1 pint should not be applied closer
than 21 days before harvest
BEETS (Red)—For control of aphids, armyworms up
to third instar, cabbage loopers, flea beetles, leaf-
hoppers, Lygus bugs, mites and stink bugs, use 1
quart per acre. If tops are to be used for food or
feed do not apply closer than 21 days before harvest
CARROTS—For control of aphids, armyworms up to
third instar, surface feeding and climbing cutworms,
flea beetles, leafhoppers and mites, use 1 quart
per acre. Do not feed tops.
CELERY—For control of aphids, armyworms up to
third instar, cabbage loopers, flea beetles, leafhop-
pers, Lygus bugs, mites and stink bugs, use 1 quart
per acre.
CUCUMBERS—For control of aphids and two-spotted
mites, use % pint per acre. Do not apply before
vining.
ONIONS—For control of thrips, use % pint per acre.
Vegetable Insects cont'd.
20
Vegetable Insects cont'd.
19
PEPPERS—For control of aphids, armyworms up to
third instar, surface feeding and climbing cutworms,
flea beetles, leafhoppers and mites, use 1 quart
per acre.
SPINACH—For control of aphids, armyworms up to
third instar, flea beetles, leafhoppers, mites, seed
corn maggots in crown and crown mites, use 1 to 2
pints per acre. For cabbage loopers, use 2 pints per
acre. Rates above 1 pint should not be applied closer
than 21 days before harvest.
TURNIPS—For control of aphids, armyworms up to
third instar, flea beetles, leafhoppers, leaf miners
and mites, use 1 to 1% pints per acre. For cabbage
loopers, use 1V4 pints per acre. If tops are to be
used for food or feed do not apply closer than 21
days before harvest
APPLY AT THE RATES INDICATED FOR THE
FOLLOWING CROPS. MAKE NO APPLICATIONS
CLOSER THAN 21 DAYS BEFORE HARVEST.
LETTUCE—For control of aphids, armyworms up to
third instar, cabbage loopers, flea beetles, leafhop-
pers and mites, use 1 quart per acre.
896.11-000.17/53 (USDA Reg. No. 524-128)
MONSANTO COMPANY
AGRICULTURAL DIVISION
ST. LOUIS, MO. 63166
136
-------
Table 20. REGISTERED USES OF METHYL PARATHION EMULSIFIABLE LIQUID
(4 LB ACTIVE INGREDIENT PER GALLON) - CROPS AND OTHER USES,
PESTS, DOSAGE RATES AND USE LIMITATIONS*/
STOP - READ THE LABEL
POISON
See Side Panels
for Antidote &
Precautions
DANCER
Keep Out of
Reach of
Children
METHYL
PAHATHION 4-E
EMULSIFIABLE
LIQUID
ORGANOPHOSPHORUS INSECTICIDE
Active Ingredients:
O.O-dimethyl O-p-nitrophenyl phosphoro-
thioate 45.4%
Xylene-range aromatic solvent .48.2%
Inert Ingredients 6.4%
Contains 4 Ib. Methyl Parathion/Gal.
Do not use, pour, spill or store near heat or open flame.
Read Label Folder for additional use precautions,
directions for use, recommendations and container
disposal. E.P.A. Reg. No. 476-1078-AA
NOT FOR HOME USE
See side panels for poison precautions, symptoms,
first aid treatment, information for physician and
posting treated areas.
NOTICE: Stauffer Chemical Company makes no war-
ranties, express or implied, including the warranties
of merchantability and/or fitness for any particular
purpose concerning this material, except those which
are contained on Stauffer's label. A-1
Stauffer
Made in USA By
STAUFFER CHEMICAL COMPANY
x WESTPORT, CT O6BBO
5 GAL. NET
a/ Sample label of Stauffer Chemical Company.
I EPA Registration No. 476-1078-AA.
137
-------
Table 20. (Continued)
DANCER-POISON-PRECAUTIONS
POISONOUS IF SWALLOWED
Even in small amounts!
Do not store near food or feed.
DON'T TOUCH ji
4
POISONOUS BY SKIN CONTACT
Poisonous if touched by hands or spilled or
splashed on skin, in eyes or on clothes (liquid
goes through clothes).
POISONOUS IF BREATHED
Poisonous if vapor or mists from sprays are
breathed. Vapors are not visible. Never work
with methyl parathion or in methyl parathion
treated areas without protective clothing and
equipment.
POISONOUS TO FISH & WILDLIFE: Toxic to fish and wildlife. Birds and other wildlife in
treated areas may be killed. Shrimp and crab may be killed at application rates recom-
mended on this label. Do not apply where these are important resources. Keep out of any
body of water. Do not apply when weather conditions favor drift from treated areas. Do
not apply where run-off is likely to occur.
138
-------
Table 20. (Continued)
WORK SAFETY RULES
USE ONLY WHEN WEARING THE FOLLOWING PRO-
TECTIVE CLOTHING AND EQUIPMENT: (1) Wear water-
proof pants, coat, hat, rubber boots or rubber overshoes.
(2) Wear safety goggles. (3) Wear mask or respirator ap-
proved by the U. S. Bureau of Mines for methyl parathion
protection. (4) Wear heavy duty natural rubber gloves.
Keep unprotected persons and children away from treat-
ed area or where there is danger of drift.
Do not rub eyes or mouth with hands. Do not smoke.
Before removing gloves, wash them with soap and water.
If you feel sick in any way STOP work and get help right
away. Tell foreman or have someone call him. Call a
physician, clinic or hospital immediately.
ALWAYS wash hands, face and arms with soap and wa-
ter before smoking, eating or drinking.
AFTER WORK, take off all work clothes and shoes.
Shower, using soap and water. Wear only clean clothes
when leaving job. DO NOT wear contaminated work
clothing.
All protective clothing and equipment should be washed
with soap and water after each use. Respirators should
be cleaned and filter replaced according to instructions
included with respirator.
POISON SIGNS (Symptoms)
Methyl parathion is a very dangerous poison. It rapidly
enters the body on contact with all skin surfaces, eyes
and by contact with skin through wet clothes. Worker who
shows any of the following poisoning signs must receive
immediate medical treatment or he may die.
Signs and Symptoms of Poisoning Are: Headache, nau-
sea, vomiting, cramps, blurred vision, pin-point pupils,
tightness of chest, labored breathing, weakness, nervous-
ness, sweating, watering of eyes, drooling or frothing
of mouth and nose, muscle spasms and coma.
POSTING TREATED AREA: Consult state regulatory
agencies for posting regulations and requirements.
FIRST AID TREATMENT
Speed is essential to stop absorption of poison.
It possible, one person should make telephone
calls while another begins treatment.
Call a physician, clinic or hospital immediately in all
cases of suspected poisoning. Explain victim exposed
to methyl parathion; describe his condition. Until medical
help is available take following steps.
IF BREATHING HAS STOPPED, start artificial respiration
immediately and continue until physician sees victim.
IF SWALLOWED and victim is awake (conscious) make
him vomit quickly. First, give soapy water or strong
salty water to drink then stroke back of throat with
finger to make victim vomit. Repeat by giving more water
and make vomit again until vomit fluid is clear. Never
give anything by mouth to an unconscious person. Have
victim lie down and keep quiet.
IN CASE OF SKIN CONTACT, immediately remove wet
clothing and shoes and flush skin with water for at least
15 minutes.
EYE CONTACT: If splashed in eyes, immediately flush
eyes with water for at least 15 minutes.
After first aid is given and physician can
not come take victim to clinic or Hospital.
Bring "Label Folder." Give to physician.
NOTE TO PHYSICIAN
ANTIDOTE—Administer atropine sulfate in large doses,
2.0 to 4.0 mg. intravenously or intramuscularly as soon
as cyanosis is overcome. Repeat at 5 to 10 minute inter-
vals until signs of atropinization appear. 2-PAM chloride
is also antidotal and may be administered in conjunction
with atropine. Do not give morphine or tranquilizers.
Methyl parathion is a strong cholinesterase inhibitor af-
fecting the central and peripheral nervous system, pro-
ducing cardiac and respiratory depression.
At first signs of pulmonary edema, the patient should be
given supplemental oxygen and treated symptomatically.
Continued absorption of the poison may occur and fatal
relapses have been reported after initial improvement.
Very close supervision is indicated for at least 48 to
72 hours.
139
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Table 20. (Cont inued)
Staufter
LABEL FOLDER
CONTAINS
ALL DIRECTIONS FOR USE
METHYL PARATHION
4-E
Organophosphorus Insecticide
Emulsif iable Liquid
POISON
DANGER
NOT FOR
HOME USE
Before Using Read All Precautions
and Directions for Use
EPA Reg. No. 476-1078 A-l
RESEALABLE BAG
I Pull flaps apart to open.
y Press along ridge to close.
IMPORTANT
SEE REVERSE SIDE OF FOLDER.
CONTAINS SAFETY LABELING
INFORMATION.
• Active Ingredient Statement
• Primary Statements of Hazard, Precaution-
ary Instructions
• Fish and Wildlife Precautions
• Work Safety Rules
• Poison Symptoms
• First Aid Treatment
• Note to Physician
8TAUFFER CHEMICAL COMPANY
WESTPORT, CT. 06880
USE PRECAUTIONS
READ ALL PRECAUTIONS AND DIRECTIONS BEFORE
USING.
Use only for crops and claims recommended.
This product is toxic to fish and wildlife. Keep out of
lakes, streams, and ponds. Birds and other wildlife in
treated areas may be killed. Do not apply when weather
conditions favor drift from areas treated. Do not con-
taminate water by cleaning of equipment or disposal of
wastes.
This product is highly toxic to bees exposed to direct
treatment or residues on crops. Protective information
may be obtained from your Cooperative Agricultural Ex-
tension Service.
In order that pesticide residues on food and forage crops
will not exceed Federal tolerances, use only at recom-
mended rates and intervals, and do not apply closer to
harvest than specified. Do not apply or allow to drift to
areas occupied by unprotected humans, or beneficial ani-
mals or onto adjoining food, fiber or pasture crops. The
grower is responsible for residues on his crops as well as
for damages caused by drift from his property to that of
others.
CONTAINER DISPOSAL
Destroy Empty Container—Never Re-Use
Completely empty contents and bury unused chemical 18
inches deep in an isolated location away from water
supplies.
Glass Container: Break container and bury 18 inches
deep.
Metal Containers: 1 gal. drum: Pour 1 quart of water into
empty drum. Add 1 tablespoon of household detergent.
Rotate drum carefully until all inner surfaces are wet.
Bury rinse solution 18 inches deep. Punch holes in top
and bottom of container, crush and bury. 5 gal. drum:
Pour 2 quarts of water into empty drum. Slowly add ¥2
cup caustic soda (lye) and 2 tablespoons of household
detergent, follow the same rinsing, destruction and burial
procedures given for 1 gal. drum. 55 gal. drum: Follow
same procedures as for 5 gal. drum except use 5 gal. wa-
ter, 2 Ib. of lye and cup of detergent.
CAUTION: Do not get rinse solution on hands, in eyes or
on clothing. Wear protective clothing and equipment. In
case of contact wash immediately with soap and water.
DIRECTIONS FOR USE
Application can be made by aircraft (except when not
recommended for certain tree fruits) or ground power
equipment by trained personnel only using approved pro-
tective equipment. Do not apply with hand equipment.
Pour specified amount of this product into nearly filled
spray tank. Add balance of water to fill tank. Keep agita-
140
-------
Table 20. (Continued)
tor running during filling and spraying operations. If
mixture does not mix readily, but tends to separate as an
oily layer, do not use as injury to plants may result. Do
not combine with wettable powders unless previous use
of the mixture has proven physically compatible and safe
to plants. Always thoroughly emulsify this product with
at least half of total water before adding wettable powder.
SUGGESTED WATER RATES FOR
AIRCRAFT AND GROUND EQUIPMENT
The actual rate required to provide thorough, uniform
coverage varies with plant growth at time of application.
Except as specified for certain uses, the following rates
are therefore intended to cover a broad range of condi-
tions.
Crop
Gal. Water/ Acre
Aircraft Ground
Vegetable and Field Crops 5-20 20- 125
Orchard 10-40 —
Orchard Crops (See exceptions below) — 300- 800
Citrus — 500-3000
Maximum permissible rate per acre, expressed as METHYL
PARATHION 4-E, is given in parenthesis ( ), after each
crop claim. Maximum permissible rates per acre and cor-
responding limitations are listed as a ready reference
of legal limits for occasions when rates higher than those
recommended are necessary to control unusual infesta-
tions. Consult State Agricultural Experiment Stations or
Cooperative State Extension Services for additional in-
formation as the timing of applications may vary with
local conditions.
IMPORTANT: Regardless of the type of equipment used
and the volume of water required to make full coverage
sprays for tree fruit and nut crops, or to make uniform
applications on vegetable and field crops, do not apply
more than the maximum permissible rate per acre as
specified for each crop claim.
RECOMMENDATIONS
FRUIT CROPS
Before reading the following crop claims, rates and re-
strictions, first read the labeling section titled DIREC-
TIONS FOR USE.
Do not use on apples, apricots and pears when foliage
is wet and under slow drying conditions, especially when
aircraft or concentrate sprays are used.
Unless otherwise specified, rates are given in terms of
METHYL PARATHION 4-E per 100 gal. of water for thor-
ough coverage application.
APPLES: European red mite (apply twice at 5 day inter-
vals), woolly apple aphid, rosy and green aphids.' Use Vz
pt. Injury to fruit and foliage may occur on Mclntosh,
Courtland and related varieties. Consult State Agricul-
tural Extension Service. Do not apply within 14 days of
harvest. (12 pt.)
APRICOTS: European red mite (apply twice at 5 day in-
tervals), and green peach aphid. Use Vz pt. Do not apply
within 14 days of harvest. Do not apply until danger of
bee poisoning has passed. (5 pt)
CHERRIES: European red mite, black cherry aphid. Use
Vz pt. Apply as needed at 7 to 10 day intervals. Do not
apply within 14 days of harvest. (5 pt.)
PEACHES: European red mite (apply twice at 5 day
intervals), green peach aphid. Use Vz pt. Do not apply
within 14 days of harvest. (8 pt.)
PEARS: Aphids. Use Vz pt. Apply twice at 5 day inter-
vals. Do not apply within 14 days of harvest. (6 pt)
PLUMS, PRUNES: European red mite (apply twice at 5
day intervals), green peach aphid and mealy plum aphid.
Use Vz pt. Do not apply within 14 days of harvest. (8 pt)
VEGETABLE, FIELD AND SPECIAL
USES
(ALSO READ DIRECTIONS FOR USE)
Unless otherwise indicated, dosages are given in pints
per acre in sufficient water to provide thorough cover-
age. Begin applications when insects first appear and
repeat at 7 to 10 day intervals as needed to maintain
control, but observe use limitations given for specific
crops.
EXPLANATORY COMMENTS
ARMYWORMS — Recommendation applies only for con-
trol up to 3rd instar stage.
ALFALFA HAY: Alfalfa weevil larvae, aphids, armyworms,
flea beetles, leafhoppers. Use 1 pt (Calif, use % pt. only)
per acre. For weevil control apply when 75% of terminals
show feeding damage. Do not apply within 15 days of
harvest. (Areas other than Calif., 2Vz pt Do not apply
this rate within 20 days of harvest. Calif., % pt.)
CAUTION — Do not apply during bloom to avoid injury
to bees. Birds and other wildlife in treated areas may be
killed.
ALFALFA (FOR SEED): Alfalfa chalcid, aphids, army-
worms, flea beetles, leafhoppers, lygus, mites and stink-
bugs. Use Vz-lVz pt. per acre by aircraft or ground equip-
ment at first sign of infestation. Do not apply within 15
days of harvest. Water Rates per Acre: Aircraft — 5 to 10
gal.; ground — 25 to 100 gal. (2Vz pt)
CAUTION — When applied to seed crops, treat in early
morning or late evening to avoid injury to pollinators.
ALFALFA, CLOVER, VETCH: Spotted alfalfa aphids. Use
Vz to 1 pt (Calif, use % pt. only). Apply in early spring.
Follow state recommendations. For the control of aphids,
armyworms, leafhoppers and mites. Use 2Vz pt. per acre
(% pt only in Calif.). Do not apply within 20 days of
harvest (15 days in Calif.). (Areas other than Calif., 2%
pt; Calif., under % pt.)
CAUTION —* Do not apply during bloom. Birds and other
wildlife in treated areas may be killed.
ARTICHOKES: Aphids, armyworms, artichoke plume moth
(use 2 pt. by air in a minimum of 10 gal. water per acre),
141
-------
Table 20. (Continued)
flea beetles, mites. Use 1V4 pt. Do not apply within 7
days of harvest. (2 pt.)
BEANS, DRY: Aphids, armyworms, flea beetles, mites.
Use 2 pt. Do not apply within 15 days of harvest. (3 pt.)
BEANS, GREEN AND LIMA: Aphids, armyworms, flea bee-
tles, mites. Use 1 to 2 pt. Rate and use limitation: 1 pt,
15 days of harvest; over 1 pt. to 2 pt., 21 days of harvest.
(3 pt.)
BEETS: Aphids, armyworms, flea beetles, leafhoppers,
mites. Use 1 to 1% pt. per acre. Do not apply within 15
days of harvest (21 days if tops are to be used as food).
(2 pt.)
CABBAGE: Aphids, armyworms, flea beetles. Use 1 to
IVz pt Do not apply within 21 days of harvest. (3 pt)
CARROTS: Aphids, armyworms. Use 1 to IVi pt. Do not
apply within 15 days of harvest. Do not use treated tops
for food or feed. (2 pt.)
CELERY: Aphids, armyworms. Use 1 to l'/4 pt Do not
apply within 15 days of harvest. (2 pt.)
COLE CROPS (Broccoli, Brussels sprouts, cauliflower, col-
lards, kale, kohlrabi): Aphids, armyworms, flea beetles.
Use 1 pt. Do not apply within 10 days of harvest on col-
lards and kale; 7 days on broccoli, Brussels sprouts,
cauliflower and kohlrabi. (1 pt)
CORN (fodder and grain, including field, sweet and pop-
corn): Aphids, armyworms, flea beetles, mites. Use Vz pt
Repeat application if necessary. Workers entering treated
fields the day of application should wear protective cloth-
ing. Do not apply within 12 days of harvest. (Vz pt.)
COTTON: Aphids, boll weevil, cotton leafworm, fleahopper,
lygus, red spider mites, thrips. Use Vz to 1 pt. Application
should be made at 4 to 5 day intervals until control is ob-
tained. For the control of cotton leaf perforator, army-
worms use 2Vz pt.
Cotton bollworm control (Calif, only): Apply 2 to 6 pt by
aircraft in 3 to 5 gal. of water per acre. Make this applica-
tion 2 or 3 times at 3 to 4 day intervals. Depending on in-
festation, repeat this series of 2 or 3 applications in 7
to 10 days or more, as needed to maintain control. Do not
sprinkle irrigate during the 3 to 4 day application inter-
vals. Late afternoon or evening treatments are preferred.
Cotton bollworm, tobacco budworm (cotton south): Use
2pt.
Workers entering treated fields within 24 hours of appli-
cation should wear protective clothing. Do not apply with-
in 7 days of hand picking or harvest. (6 pt)
GOOSEBERRIES: Aphids. Use Vz pt. Do not apply within
15 days of harvest. (Vz pt)
HOPS: Aphids, armyworms, leafhoppers, mites. Use 1 pt
Do not apply within 15 days of harvest. (2 pt.)
LETTUCE: Aphids, armyworms. Use 1 to IVfe pt. Do not
apply within 21 days of harvest. (2 pt.)
ONIONS: Onion thrips. Use 1 pt. in 15 gal. of water for
aircraft application; 10 to 25 gal. by ground equipment
Repeat at weekly intervals. Do not apply within 15 days
of harvest. (1% pt.)
PEANUTS: Leafhoppers, lesser cornstalk borer, red-
necked peanutworm, spider mites, three-cornered alfalfa
hopper, webworm. Use 1-3/5 pt Do not apply within 15
days of harvest. (1-3/5 pt.)
POTATOES: Aphids, armyworms, flea beetles, mites. Use
2 pt Do not apply within 5 days of harvest. (3 pt)
PEAS: Aphids, armyworms. Use 1 pt. Do not apply within
10 days of harvest. (1 pt)
PEPPERS: Aphids, armyworms. Use 1 to 2 pt. Do not use
within 15 days of harvest (2 pt)
RICE (Calif, only): Rice leaf miner and tadpole shrimp.
Apply at the first sign of infestation after planting using
IVz pt. in 5 to 10 gal. water by aircraft. Restrict spill from
rice fields for 5 days. Do not apply within 15 days of har-
vest CAUTION: Do not use within 14 days of applica-
tion of Stam F-34 or Rogue. Injury may result Shrimp
and crab may be killed at these rates. Do not apply where
these are important resources. (IVz pt.)
SAFFLOWER: Aphids and lygus bugs. Use 1 pt. Do not
apply after flowering. (1 pt.)
SMALL GRAINS (Barley, oats and wheat): Aphids (green
bug), black grass bug (Irbisia), brown wheat mite (Petro-
bia), and stink bugs. Apply Vz to 1 pt. For armyworms and
leafhoppers apply 2Vz pt. Use limitations: Vz pt — none;
over Vz and up to IVz pt, 15 days.
SOYBEANS: Stink bugs, three-cornered alfalfa hopper
and velvet bean caterpillar. Use % to 1 pt Do not apply
more than 2 applications per growing season. Do not ap-
ply within 20 days of grazing or harvest (2 pt)
SPINACH:: Aphids, armyworms. Use 1 to 2 pt. Rate and
use limitation: 1 pt — do not apply within 14 days of
harvest; over 1 pt. to 2 pt, 21 days of harvest. (2 pt.)
TOBACCO: Green June beetle. 1 pt Do not apply within
5 days of priming tobacco or within 15 days of cutting
tobacco. Avoid contact with plant juices when priming or
cutting tobacco. Workers entering treated fields within 24
hours after application should wear protective clothing.
(1 Pt.)
TOBACCO PLANT BED DRENCH: Green June beetle. %
pt per 100 gal. water. Apply 100 gal. of drench per 100
sq. yd. Apply to plant beds with sprinkling can. Applica-
tion should be made only by trained operator. Do not
apply within 5 days of transplanting.
TOMATOES: Aphids, armyworms, flea beetles, russet
mite. Use Vz to 1 pt Rate and use limitation: 1 pt, do
not apply within 10 days of harvest; over 1 pt to 3 pt,
15 days of harvest. (3 pt.)
TURNIPS (Coastal area of Calif.): (Foliage treatment)
cabbage aphids. Apply IVz pt. when aphids are present
and colonies are abundant. Repeat as necessary to main-
tain control but do not apply within 15 days of harvest
(21 days if tops to be used for food or feed). (1-3/5 pt)
FOREST AND CHRISTMAS TREE PLANTINGS: To control
European pine shoot moth and Nantucket pine tip moth
use 2 pt per acre in 5 to 50 gal. water. Repeat applica-
tions if necessary.
142
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It is unlawful in California to sell or deliver methyl parathion-
containing pesticide products to any person required to be in possession
of a permit under this code, unless the person or his agent signs a state-
ment that he indeed has a valid permit to use the product.
Similar restrictions on the use of methyl parathion are in effect in
a number of other states.
Details of the pesticide use and application laws in each of the
states that regulate pesticides have been summarized by EPA, Office of
Pesticide Programs, in a publication entitled Guide for Analyzing Laws.
This pesticide law digest is being kept current by addition and replace-
ment pages issued to holders from time to time.
In addition to these statutory restrictions on the use of methyl
parathion imposed by Federal and state laws, many states amplify methyl
parathion product labels by issuing further, more specific use recommen-
dations or suggestions designed to accommodate local or regional require-
ments. These are usually issued jointly by the State Agricultural
Experiment Station and Extension Service in cooperation with the U.S.
Department of Agriculture. These state insecticide use recommendations
or suggestions are issued or revised annually.
Production and Domestic Supply
Volume of Production - The United States Tariff Commission 1972 final
report on synthetic organic chemicalsi/ listed the following production
volumes of methyl parathion for the period 1967-1972.
Production volume
Year (active ingredient)
1967 33,344,000 Ib
1968 38,163,000 Ib
1969 50,572,000 Ib
1970 41,353,000 Ib
1971 37,226,000 Ib
1972 51,076,000 Ib
I/ U.S. Tariff Commission, Synthetic Organic Chemicals, U.S. Production
and Sales, 1972, TC Publication 681 (1973).
143
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The Tariff Commission named four basic producers of methyl para-
thion in the United States: Monsanto Company, Stauffer Chemical Company,
Kerr-McGee Chemical Corporation, and Velsicol Chemical Corporation.
i / v
According to Midwest Research Institute^' estimates, Monsanto pro-
duced about 25 million pounds of methyl parathion in 1972; Stauffer
about 15 million pounds; Kerr-McGee about 8 million pounds; and Velsicol
about 3 million pounds.
Imports - Imports of pesticides classified as "benzenoid chemicals"
(including methyl parathion) are repprted in a 1973 U.S. Tariff Commission
annual report2,/. According to the report, 1,102,300 Ib of methyl parathion
were imported into the United States in 1972.
Exports - Pesticide exports are reported by the Bureau of the Census
annually. Technical (unformulated) methyl parathion and parathion
are included in this report in Schedule B, Section 512.0652. Formulations
of methyl parathion (and of all other cyclic and acyclic organic phosphate
insecticides) are included in Schedule B, Section 599.2035, entitled
"Organic Phosphate Containing Pesticidal Preparathions, Except Household
and Industrial and Except Fly Sprays and Aerosols.1—'
Total exports of organic phosphate insecticides in these two cate-
gories for 1972 were as follows:
Section 512.0652 (methyl parathion and parathion technical) 16,533,940 Ib
Section 599.2035 (organic phosphate containing formulations) 15,898,884 Ib
To derive the 1972 export volume of methyl parathion from these com-
posite 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
if Midwest Research Institute/RvR Consultants, "Production, Distribution,
~ Use, and Environmental Impact Potential of Selected Pesticides"
(draft), Council on Environmental Quality, Contract No. EQC-311
(15 March 1974).
2/ U.S. Tariff Commission, Imports of Benzenoid Chemicals and Products,
~" TC Publication 601 (1973).
3/ U.S. Bureau of the Census, U.S. Exports, Schedule B, Commodity by
Country, Report FT 410.
144
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against existing knowledge of the crop protection problems and the pesti-
cide trading patterns of the countries of destination. Additional infor-
mation was obtained from confidential sources, from the U.S. Agency for
International Development (AID), and from other sources. Based on this
data the 1972 export volume of methyl parathion is estimated at 12.5
million pounds of active ingredient.
Domestic Supply - The information presented in the preceding three sections
permits an estimate of the domestic supply of methyl parathion in the U.S.
in 1972. Adding imports to production, and subtracting exports, Midwest
Research Institute estimates that 39,700,000 Ib of methyl parathion active
ingredient were used domestically in 1972.
Comparable estimates for 1973 cannot be made at this time because
the U.S. Tariff Commission Report on the production and sales of pesti-
cides and related products in 1973 was not available at the time of
review.
Formulations - Methyl parathion is available to users in the United States
in several different formulations, and through a considerable number of
suppliers. The basic producers of technical methyl parathion sell a
large share of their production to formulator-customers in the form of
an 80% technical solution. Formulators then prepare and sell formulations
containing methyl parathion under their own labels and brand names to
end users, either directly, or through wholesalers and/or retailers.
In areas of heavy use of methyl parathion-toxaphene combinations,
the two ingredients are often mixed and formulated in bulk and dispensed
into spray equipment directly from bulk tanks in the field, thus bypassing
drums, cans, and the problem of disposal of these containers after use.
Frear (1972)1/ lists more than 30 pesticide products containing
methyl parathion as the only active ingredient. These include 27 spray-
able formulations, 3 dust formulations, and 4 manufacturing concentrates.
No granular or aerosol formulations of methyl parathion are listed (or
registered). Among the spray formulations, those containing concentra-
tions offered are 2%; 2 lb/gal.; 3.2 Ib/gal.; and 4.25 Ib/gal. Also
offered, are 70 and 80% technical solutions and at least one 25% wet-
table powder formulation.
I/ Frear, D. E. H., Pesticide Handbook - Entoma. 24th Edition, College
Science Publishers, State College, Pennsylvania (1972).
145
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In addition, there are a considerable number of liquid and some dry
formulations containing methyl parathion in combination with other insec-
ticides and/or fungicides. Among these combination formulations, an emul-
sifiable liquid containing 3 Ib of methyl parathion and 6 Ib of parathion
per gallon has recently made considerable gains in volume of use. It is
the only formulated parathion or methyl parathion product currently marketed
by Monsanto, the largest U.S. producer of both products. Similar parathion-
methyl parathion emulsifiable liquids are offered by at least two other
formulators.
Use Patterns of Methyl Parathion in the United States
General - The entire volume of methyl parathion used in the United States
in 1972 (the most recent year for which sufficient data for such estimates
are available) was used in agriculture. There were no significant uses
of methyl parathion by industrial, commercial, or institutional pesticide
users; by Federal, state, county, local or other governmental agencies;
or by home and garden users.
Surveys on the use of pesticides by farmers in the United States
were conducted by the U.S. Department of Agriculture in 1964, 1966, and
1971 (Agricultural Economic Reports No. 131, published in 1968; No. 170,
published in 1970; and No. 252, in press and soon to be published). Data
on the uses of methyl parathion in 1972 were obtained by RvR Consultants.
The following farm uses of methyl parathion were reported:
Year Source Farm Use
1964 USDA 9,985,000 Ib of active ingredient
1966 USDA 8,002,000 Ib of active ingredient
1971 USDA 27,563,000 Ib of active ingredient
1972 RvR 39,700,000 Ib of active ingredient
These figures indicate a sharp upward trend in the rate of use of
methyl parathion by farmers between 1964-66 and the present.
As outlined in detail in the first part of this subsection, methyl
parathion controls a considerable number of insect pests, and some mite
species. The 40-page section on methyl parathion in the "EPA Compendium
of Registered Pesticides," Vol. Ill, pages D-41.1 through 41.40, includes
62 crops and other uses for which methyl parathion is registered.
Table 21 presents a breakdown of the estimated uses of methyl para-
thion in the United States in 1972 by regions and major crops. The
following information sources were used in arriving at these estimates:
1. The 3 USDA surveys of pesticide uses by farmers mentioned above.
146
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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
parathion 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 these diverse sources were carefully analyzed, correlated,
cross-checked and cross-validated. The resulting estimates as summarized
in Table 21 are believed to be the best and most up-to-date information on
the use patterns of methyl parathion in the United States currently
available.
Methyl Parathion Use Patterns by Regions - Close to 80% of the estimated
total domestic use of methyl parathion, i.e., about 31 million pounds of
AI, were used in 1972 in the South Central Region, primarily on cotton.
An estimated 2.1 million pounds of the product were used on soybeans in
the East South Central states, and much smaller quantities on a variety
of other field and vegetable crops.
The Southeastern states used an estimated 5.0 million pounds of methyl
parathion. Of this total", about 3.7 million potinds were used on cotton,
about 900,000 Ib on soybeans, the balance (400,000 Ib) on a variety of
other crops.
147
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Table 21. ESTIMATED USES OF METHYL PARATHION IN THE U.S.
BY REGIONS AND MAJOR CROPS, 1972
00
Crop
, -
Region
Northeast^./
Southeast^-/
North Central^/
East South Centra l£/
West South Centra IS/
Northwest!/
Southwest^/
Totals, 50 states
Cotton
w w»
3,700
Negl.
13,500
14,600
__
1,700
33,500
Soybeans
Thousands
_ _
900
100
2,100
Negl.
--
3,100
i
Other
field
crops
of pounds
Negl.
100
Negl.
100
100
450
500
1,250
Vegetables
of active
Negl.
100
Negl.
100
100
100
500
900
All other
crops and
uses
ingredient
Negl.
200
Negl.
200
200
150
200
950
Totals,
all
uses
Negl.
5,000
100
16,000
15,000
700
2,900
39,700
Sources: 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, Michigan, Wisconsin, Minnesota, Iowa, Missouri, North Dakota, South Dakota,
Nebraska, Kansas, Illinois
jd/ Kentucky, Tennessee, Arkansas,. Louisiana, Mississippi, Albania
_e/ Oklahoma, Texas
I/ Montana, Idaho, Wyoming, Colorado, Utah, Washington, Oregon, Alaska
£/ New Mexico, Nevada, Arizona, California, Hawaii
-------
An estimated 2.9 million pounds of methyl parathion were used in the
Southwestern states. Again, cotton accounted for the largest share of
this total (1.7 million pounds), while the remaining 1.2 million pounds
were used on field, vegetable, and other crops.
An estimated 700,000 Ib of methyl parathion AI were used in the
Northwest in 1972, primarily on field crops (small grains, alfalfa, sugar
beets), the balance going on vegetable and other crops.
An estimated 100,000 Ib of methyl parathion were used in the North
Central states in 1972, primarily on soybeans.
There were no significant uses of methyl parathion in the Northeast
in 1972.
Methyl Parathion Use Patterns by Crops - Methyl parathion is primarily
a cotton insecticide. Cotton accounts for about 85% of the total quan-
tity of methyl parathion used in the United States in 1972. Methyl para-
thion is registered and recommended against 20 different insect and mite
pests on cotton. In 1972, many pesticide suppliers in the "cotton south"
reported selling record quantities of cotton insecticides that year,
especially toxaphene and methyl parathion. Methyl parathion was short
in supply in many places.
An estimated 3.1 million pounds of methyl parathion AI were used
on soybeans in 1972. The largest share of this total was used in the
East South Central states, followed by the Southeastern states, with
only about 100,000 Ib used on Northern soybeans. Methyl parathion
use on soybeans was probably much larger in 1973 because of an out-
break of the green cloverworm in the Northern soybean growing areas.
Other field crops (including small grains, alfalfa, sugar beets, rice,
and others), vegetable crops (including artichokes, tomatoes, lettuce,
beans, and others), and other crops and uses account for the remaining
quantities of methyl parathion used in the United States in 1972.
Methyl Parathion Uses in California - The State maintains detailed records
of pesticide uses by crops and commodities which are published quarterly
and summarized annually. Table 22 summarizes the uses of methyl parathion
in California by major crops for the 4-year period 1970-1973. The total
volume of methyl parathion used during this period varied from about
730,000 Ib in 1973 to 1,011,000 Ib in 1971. Quantities used on individual
crops showed even greater variations. For instance, the use of methyl
parathion on cotton declined from 224,000 Ib in 1970 to 90,000 Ib in 1973.
Methyl parathion quantities used on artichokes varied from 77,000 Ib in
1971 to 151,000 Ib in 1973.
Methyl parathion has also been used extensively for vector control
(mosquito larvae) in California. However, quantities used have declined
from 221,000 Ib in 1970 to 34,000 Ib in 1973.
149
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Table 22.* METHYL PARATHION USES IN CALIFORNIA BY
MAJOR CROPS AND OTHER USES, 1970-1973
Year
Crop 1973 1972 1971 1970
Thousands of pounds of active ingredient
Almonds
Artichokes
Beans
Tomatoes
Lettuce
Cotton
Sugar beets
Alfalfa
Rice
Vector control
All other uses
Totals
151
31
94
70
90
53
49
32
34
121
730^
199
39
62
54
145
59
51
23
52
84
769
77
30
87
53
346
87
106
30
63
132
1,011
114
17
49
73
224
37
62
15
221
118
930
*California Department of Agriculture, Pesticide Use Reports for 1970, 1971,
1972, and 1973.
a/ Quantity used on almonds in 1973 and 1973 total reduced by
474,000 Ib to adjust for apparent system error; see text.
150
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Tables 23 and 24 present methyl parathion uses in California by crop,
number of applications, pounds of active ingredient, and number of acres
treated, for 1972 and 1973, respectively, the two most recent years for
which such data are available. In both years, methyl parathion was used
in California on about 75 different crops.
Regarding the California Department of Agriculture's reported figure
of 478,595 pounds of methyl parathion used on the state's almond crops
in 1973 (Table 24), available figures for the three preceeding years
show that methyl parathion uses on almonds were considerably lower:
1970, 422 Ib; 1971, 86 Ib; 1972, 979 Ib. Based on an analysis of past
level of use and the number of acres treated in 1973, Midwest Research
Institute has revised the reported 1973 figure for methyl parathion uses
on almonds. (See Table 22.) *
At the present time, no other state records or publishes pesticide
use data in a form or detail comparable to that of California. Limita-
tions of time and resources did not permit development for this review
of estimates on the uses of methyl parathion by crops and states.
Summary - In 1972, almost 40 million pounds AI of methyl parathion were
used in the United States. Of this total, about 85% (33.5 million pounds)
were used on cotton; 3.1 million pounds on soybeans; the balance on other
field crops, vegetables, and on other crops and for other purposes,
including control of mosquito larvae.
Geographically, about three-fourths of the total quantity of methyl
parathion used in the U.S. in 1972 was used in the South Central states.
The remaining one-fourth of the total methyl parathion volume was used
(regions listed in decreasing order of volume of use) in the Southeast;
the Southwest; the Northwest; and in the North Central states. There
were no significant uses of methyl parathion in the Northeast in 1972.
In California, methyl parathion was used on about 75 different crops,
and for the control of mosquito larvae. However, total use of methyl
parathion in California amounted to less than 2% of the national total.
* In a personal communication, the California Department of Agriculture
agree that the reported figure of 478,595 Ib was most likely erroneous.
The agency did not account for the discrepancy.
151
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Table 23. USE OF METHYL PARATHION IN CALIFORNIA IN 1972
. BY CROPS, APPLICATIONS, QUANTITIES, AND ACRES TREATED
Commodity
Alfalfa
Alfalfa for seed
Almond
Anise
Apple
Apricot
Artichoke
Barley
Beans, dry edible
Beans, green or forage
Beans for seed
Beet
Broccoli
Brussels sprouts
Cabbage
Cantaloupe
Cardoni (cardoon)
Carrot
Cattle lot
Cauliflower
Celery
Chinese cabbage
Citrus
Cole crops
Conifer
Corn/ field
Corn/ sweet
Cotton
County or city parks
Crenshaw melon
Cucumber or pickle
Eggplant
Endive
Fallow (open ground)
flowers
Grape
Leek
Lemon
Lettuce/head
Lettuce/ leaf
Melons
Applications
988
123
10
1
3
9
2,498
23
526
18
3
147
120
163
219
8
4
294
1
276
803
2
16
2
1
68
63
2,016
1
2
1
2
13
16
11
3
7
2,397
76
3
Pounds
31,314.81
20,097.15
978.86
13.16
85.00
432.86
199,145.46
1,291.95
38,134.44
493.87
29.98
4,859.64
2,136.17
4,200.54
3,855.50
162.88
6.00
9,941.93
1.44
3,811.87
14,044.81
5.46
776.78
4.00
39.46
2,322.56
6,037.83
145,003.04
7.48
7.30
23.49
11.08
11.08
305.80
151.13
1,750.74
9.96
395.24
53,717.46
600.61
180.09
Acres
86,197.70
16,029.00
669.00
15.00
34.00
298.50
206,614.00
2,420.00
42,872.50
810.00
143.00
10,375.68
2,371.90
4,399.50
4,644.83
592.00
6.00
10,676.45
6.00
5,108.50
13,317.05
8.00
445.50
8.00
76.00
3,778.00
5,532.00
184,639.90
10.00
105.00
15.00
15.00
354.00
172.00
2,174.00
26.00
146.00
87,004.27
912.75
310.00
152
-------
Table 23.* (Continued)
Commodity
Nectarine
Non-Agricultural areas
Nursery stock
Oats
Olive
Onion/dry
Onion/green/spring/shallot
Orange
Ornamentals
Ornamental bedding plants
Other agencies
Pasture/rangeland
Peach
Pea
Pepper/bell
Plum
Potato
Prune
Pumpkin
Radish
Residential control
Rice
Rye
Saf flower
Salsify
Sorghum
Spinach
Squash, summer
Strawberry
Sudan grass
Sugar beet
Sunflower seed
Swiss chard
Tomato
Turf
Turnip
University of California
Vector control
Walnut
Water areas
Wheat
Total
*
Applications
50
8
1
2
20
134
26
78
14
2
16
41
15
31
37
253
10
1
4
232
1
2
1
32
68
4
13
2
1,688
1
1
1,118
16
3
3
2
7
14,874
Pounds
654.97
144.00
32.67
54.25
1,381.62
5,025.82
575.69
6,741.13
130.71
32.75
338.75
3,792.33
1,545.44
156.04
638.16
922.12
2,591.47
986.25
26.25
49.38
7.43
23,311.59
25.98
58.12
2.32
742.75
2,198.97
38.26
547.58
142.87
58,991.44
180.74
8.80
61,646.95
1,230.90
11.71
75.12
51,302.38
133.32
69.99
340.18
768,603.17
Acres
400.00
338.00
50.00
100.00
389.50
6,971.00
614.00
2,390.41
155.00
38.00
1,257.00
715.00
174.00
719.50
451.00
13,917.93
485.00
100.00
57.00
41,144.61
70.00
107.00
29.00
2,174.50
3,570.00
74.50
565.00
170.00
136,235.88
160.00
2.00
65,840.00
1,801.00
15.00
121.00
379.00
805.00
975,917.86
\ >
•*Ealifornia Department of Agriculture, Pesticide Use Report 1972.
153
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Table 24. USE OF METHYL PARATHION IN CALIFORNIA IN 1973
BY CROPS, APPLICATIONS, QUANTITIES, AND ACRES TREATED
Commodity
Alfalfa
Alfalfa for seed
Almond
Apple
Apricot
Artichoke
Asparagus
Avocado
Barley
Beans, dry edible
Beans, green or forage
Beet
Broccoli
Brussels sprouts
Cabbage
Cantaloupe
Cardoni (cardoon)
Carrot
Cattle lot
Cauliflower
Celeriac
Celery
Chinese cabbage
Citrus
Corn/field
Corn/ sweet
Cotton
Cucumber or pickle
Eggplant
Fallow (open ground)
Flowers
Grape
Leek
Lemon
Lettuce/head
Lettuce/leaf
Melons
Nectarine
Non-Agricultural areas
Nursery stock
Olive
Onion/dry
Applications
851
292
18
2
4
3,081
1
2
63
619
3
485
222
63
200
2
1
279
1
332
2
748
1
1
21
22
2,039
3
3
12
6
20
2
20
2,983
36
6
21
2
1
34
188
Pounds
30,426.49
18,132.82
478,595.34
37.25
160.69
151,268.62
25.99
124.20
5,216.31
30,734.31
51.65
14,496.72
3,820.23
1,940.60
3,389.81
14.78
6.93
10,255.21
31.19
5,435.99
66.80
14,000.19
4.74
62.50
656.58
547.07
89,932.62
70.20
33.24
410.75
1,023.60
869.36
11.86
1,994.01
69,817.69
343.29
88.48
440.71
80.72
3.16
2,458.36
8,544.64
Acres
77,405.30
23,197.00
2,859.58
27.00
81.50
173,033.31
30.00
155.00
13,470.00
42,822.05
141.00
38,376.40
4,144.14
1,903.00
4,662.50
20.00
5.00
10,926.72
36.00
5,839.24
46.00
12,222.17
5.00
25.00
1,772.00
2,364.00
186,202.64
98.00
45.00
163.25
871.00
1,670.00
27.00
312.00
123,893.98
615.18
285.00
249.50
205.00
10.00
617.50
10,393.00
154
-------
Table 24.* (Continued)
Commodity
Onion/green/spring/shallot
Orange
Ornamentals
Pasture/rangeland
Peach
Pear
Pea
Pepper/bell
Plum
Potato
Prune
Residential control
Rice
Safflower
Soil (fumigation only)
Sorghum
Spinach
Squash, summer
Squash, winter
State highway
Strawberry
Sudan grass
Sugar beet
Sunflower seed
Sweet potato
Swiss chard
Tangelo
Tomato
Turf
Turnip
University of California
Vector control
Walnut
Water areas
Wheat
Total
Applications
12
101
47
13
67
4
144
31
24
172
14
253
14
4
56
48
3
1
16
3
1,871
6
28
1
2
1,439
2
5
4
4
231
17,312
Pounds
252.01
9,275.04
621.20
264.94
3,729.29
6.50
450.23
653.02
597.63
11,435.73
1,608.05
.24
31,651.23
959.39
404.16
2,399.45
1,260.69
10.03
18.71
3.86
377.93
21.57
53,203.88
2,049.49
739.18
.26
40.50
94,371.80
76.64
27.91
72.83
34,197.97
50.89
216.07
7,349.05
1,204,023.07
Acres
295.00
3,955.00
743.00
1,772.00
2,382.75
13.00
669.50
827.50
257.50
12,246.50
745.25
42,167.00
2,534.00
194.00
3,244.00
1,710.06
13.00
100.00
437.00
96.00
151,892.78
1,680.00
1,574.00
2.00
13.00
101,472.60
290.00
41.00
64.00
1,224.00
14,156.00
1,088,038.40
California Department .of Agriculture, Pesticide Use Report 1973.
155
-------
PART III. MINIECONOMIC REVIEW
CONTENTS
Introduction 157
Cotton 159
Efficacy Against Pest Infestation 159
Cost Effectiveness of Pest Control 162
Sorghum 166
Efficacy Against Sorghum Midge Infestation 166
Cost Effectiveness of Sorghum Midge Control 166
Greenbug 167
Efficacy Against Greenbug Infestation 167
Cost Effectiveness of Greenbug Control 168
Wheat 168
Efficacy Against Greenbug Infestation 169
Cost Effectiveness of Greenbug Control ... 170
Sunflowers 170
Efficacy Against Pest Infestation 171
Cost Effectiveness of Pest Control 171
References 173
156
-------
This section contains a general assessment of the efficacy and cost
effectiveness of methyl parathion. Data on the production of methyl
parathion 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 this report. The 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 had 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 untreated test plot.
The difference in yield should be the increase due to the use of the pesti-
cide. 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. Midwest Research
Institute's review of the literature and EPA registration files revealed
that experimental tests comparing crops treated with specific pesticides
to the same crop without treatment are conducted by many of the state agri-
cultural experimental 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 condi-
tions, 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 .infestation
frequent pesticidal* use can result in a high yield increase because the
crop from the untreated test plot is practically destroyed. Conversely,
in a year of light (or insignificant) infestation, the yield increase will
be slight (or undetectable).
157
-------
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 17, 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 methyl parathion 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 methyl parathion
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 methyl parathion applied to generate the range
of economic benefits in dollars per acre.
Most of the studies concerning the efficacy and yield charges due
to the use of methyl parathion have been conducted on cotton crops for
the control of the bollworm, boll weevil and tobacco budworm. The
Texas Agricultural Experiment Station has conducted yearly studies which
provide a history of the changes in efficacy. Sufficient data were also
available from experiment stations in Louisiana, Mississippi, Georgia,
and South Carolina.
Other pest crop combinations for which we found literature that com-
pared yields with use rates included: the sorghum midge and greenbug on
sorghum, the greenbug on wheat and the sunflower moth on sunflowers.
These results are summarized in the following paragraphs.
\J 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).
158
-------
Cotton
The use of methyl parathion on cotton in 1972 is estimated at
33,500,000 Ib of active ingredient, i.e., 84.3% of the total domestic
consumption. It is primarily used to control the cotton boll weevil,
bollworm and tobacco budworm, but is also recommended for control of
thrips, cotton leafworms, grasshoppers, fall armyworms, spider mites,
fleahoppers, lygus bugs, aphids, garden webworms, false chinch bugs,
cabbage loopers and cutworms.
Methyl parathion can be applied by itself or in combinations with
other insecticides. Prior to the restriction of DDT a typical applica-
tion consisted of 0.5 gal/acre of a mixture of 4 Ib toxaphene, 2 Ib DDT
and 0.5 Ib of methyl parathion to control bollworms. The number of ap-
plications would vary depending upon the degree of infestation. A high-
use farmer might make 14 to 15 total applications, with one or two of
these applications consisting solely of methyl parathion to suppress
the late hatch of bollworms. Many states are now recommending a formu-
lation consisting of 6 Ib of toxaphene and 3 Ib of methyl parathion per
gallon at a rate of 1 to 2 qt/acre.
Efficacy Against Pest Infestation - The use of methyl parathion
expanded significantly as resistance of the tobacco budworm to DDT
increased. Adkisson et al. (1965)Jk/ found a high level of DDT resis-
tance in the budworm and bollworm. Tests showed that methyl parathion
killed 85% of the bollworm larvae when applied at 0.25 Ib/acre whereas
1.0 Ib/acre of DDT killed only 51%.
Wolfenbarger et al. (1971)27 found that methyl parathion killed 85%
of the bollworms and tobacco budworms. Yields in a test at Brownsville,
Texas, in 1967 increased 689 Ib of seed cotton over the check. Good con-
trol of the bollworm, tobacco budworm, and pink bollworm was achieved.
I/ Adkisson, Perry L., and Stanley Nemec, "Efficiency of Certain Insecti-
cides for Killing Bollworms and Tobacco Budworms," Progress Report
PR-2357, Texas Agr. Exp. Sta. (1965).
2f Wolfenbarger, D. A., and Rex McGarr, "Low Volume and Ultra-Low
Volume Sprays of Malathion and Methyl Parathion for Control of
Three Lepidopterous Cotton Pests," Production Research Report No.
126, U.S. Department of Agriculture and Texas Agr. Exp. Sta. (1971),
159
-------
. ,, Nemec et al. (1968)!/ evaluated ULV and CLV methyl parathion sprays
at College Station, Texas in 1966 and achieved 1007. kill of the boll-
worm and budworm 48 hr after application of 1.0 Ib/acre. They concluded
that ULV sprays should provide more effective and economical control.
t
Hopkins et al. (1970)^/ evaluated methyl parathion and other in-
secticides in 1968 and 1969 at Florence, South Carolina, and found that
methyl parathion gave good control of the bollworm and boll weevil.
Yields increased 1,629 Ib/acre in 1968 and 867 Ib/acre in 1969 compared
to the untreated checks. The yields from the untreated checks were 255
and 10 Ib/acre, respectively.
o /
Adkisson et al. (1967)— compared various insecticides and found that
methyl parathion at 1.0 Ib/acre killed 100% of the bollworm larvae after
48 hr and 89% kill was- achieved when methyl parathion was applied at 0.5
Ib/acre. They also found that 0.75 Ib/acre methyl parathion provided
97% kill of tobacco budworm larvae after 48 hr and 100% kill of the adult
boll weevil under the same conditions when 0.25 Ib/acre were applied.
These tests were conducted at College Station, Texas, in 1966.
McGarr et al. (1969)— evaluated insecticides at Brownsville, Texas,
in 1968 and reported that although methyl parathion was effective against
the budworm and bollworm it did not give adequate control. Yield increases
from three tests varied from 6 to 219 Ib/acre. When methyl parathion was
applied at 2.0 Ib/acre, better control was achieved and yields increased
845 Ib/acre.
In 1968, Nemec et al. (1968)—' noted that the tobacco budworm popula-
tion in the Lower Rio Grande Valley, and perhaps near College Station
I/ Nemec, S. J., P. L. Adkisson, and H. W. Dorough, "Laboratory Tests
of Ultra-Low Volume and Conventional Low Volume Sprays for Con-
trolling the Bollworm and Tobacco Budworm," J. Econ. Entomol.,
61:209-213 (1968).
2/ Hopkins, A. R., H. M. Taft, W. James, and C. E. Jernigan, "Evalu-
ation of Substitutes for DDT in Field Experiments fof Control of
the Bollworm and the Boll Weevil in Cotton, 1967-1969," J. Econ.
Entomol., 63:848-850 (1970).
3/ Adkisson, Perry L., and S. J. Nemec, "Insecticides for Controlling
the Bollworm, Tobacco Budworm, and Boll Weevil," MP-837, Texas
Agr. Exp. Sta. (1967).
47 McGarr, R. L., and D. A. Wolfenbarger, "Field Evaluations of Insecti-
cides for Control of Cotton Insects, Brownsville, 1968," Progress
Report PR-2670, Texas Agr. Exp. Sta. (1969).
5_/ Nemec, S. J., P. L. Adkisson, and H. W. Dorough, "Laboratory Tests of
Ultra-Low Volume and Conventional Low Volume Sprays for Controlling
the Bollworm and Tobacco Budworm," J. Econ. Entomol., 61:209-213 (1968)
160
-------
had developed a low-level resistance to methyl parathion: large doses
of the insecticide were needed to kill the budworms in laboratory tests,
The Lp^o values had also indicated a 2.0- to 2.5-fold increase over the
previous year. These tests showed a 97% kill in 48 hr when applied
at 2.0 Ib/acre on College Station larvae. This dropped to a 41% kill
rate when 0.5 Ib/acre was applied. There were no indications of re-
sistance in the bollworm or voll weevil.
Nemec conducted similar tests in 1969 (Nemec, 197Q1/) and found
that the U>5Q value for methyl parathion increased 1.5-fold over the
1968 value in budworms from the Brazos River Valley and twofold over
the 1968 value in the Welasco area. Methyl parathion at 2.0 Ib/acre
resulted in a 90% kill in 48 hr at College Station in 1969. At 0.5
Ib/acre it gave a 44% kill. In Welasco the results at the above rates
were 79% and 23%, respectively.
Nemec et al. (1973)—' summarized the yearly tests comparing the
effect of methyl parathion on the budworm and bollworm. He reported
that prior to 1968 when resistance was detected in the budworm the
cost of control was $28/acre. By 1972 the cost for control of the
bollworm complex averaged $60/acre due to higher rates and more fre-
quent applications of insecticides, greater populations of the budworm
and higher costs of certain insecticides.
The results of tests showed that the LDcjQ values for methyl para-
thion on the budworm increased 50-fold between 1964 and 1972 at College
Station, Texas. A fivefold increase from 1968 to 1972 was reported in
the Rio Grande Valley, Texas.
Some resistance of the bollworm to methyl parathion was also in-
dicated. The LD50 values at College Station were at the same level
from 1967 to 1971, but doubled in 1972. Bollworms in the Pecos area
were shown to be more tolerant to methyl parathion than those from
College Station.
I/ Nemec, S. J., "Topical Application and Caged Plant Evaluations of
Insecticide Toxicities to Bollworms, Tobacco Budworms and Boll
Weevils," Progress Report PR-2845, Texas Agr. Exp. Sta. (1970).
2/ Nemec, S. J., and P. L. Adkisson, "Organophosphate Insecticide
Resistance Levels in Tobacco Budworm and Bollworm Populations
in Texas, Investigations of Chemicals for Control of Cotton
Insects in Texas," Technical Report No. 73-20, pp. 18-25, Texas Agr.
Exp. Sta. (1973):
161
-------
Wolfenbarger et al. (1973)-=-' evaluated budworm resistance to
methyl parathion in'Texas, Mexico, Central America, Florida, and
Mississippi, and found the highest levels of resistance in the Mante
Tampico area of Mexico. They concluded that these insects in this
area and Brownsville, Texas were resistant to methyl parathion while
those in Mississippi, Southern and Western Mexico were susceptible. The
bollworms from Central America and Southern Mexico were resistant to
methyl parathion whereas the United States resident bollworms were sus-
ceptible.
Apparently, the resistance of the budworm to methyl parathion is
limited to the Texas area. Canerday (1974)—' showed that there were
no substantial and consistent differences in the response of bollworms
and budworms to methyl parathion in tests conducted in Georgia between
1970 and 1972.
Cost Effectiveness of Pest Control - Numerous studies have been con-
ducted comparing increased yields of methyl parathion treated cotton.
Most of these studies were made available from the Texas Agricultural
Experiment Station and were supplemented by tests conducted in Mississippi,
Louisiana, and South Carolina. The tests covered the period from 1956
to 1972. The 1972 price received by farmers for cotton was 24.0<:/lb for
lint. Additional income from cottonseed of 4.20/lb and government price
supports of 12.5C/lb brought the total income to 40.70/lb of cotton
(Agricultural Statistics, 19733/). Methyl parathion costs averaged
$l/lb in 1972 (Chambers and Miller, 1974A./).
The range of yield changes from all of the data reviewed varied
from a loss of 52 Ib/acre to an increase of 1,629 Ib when compared to
untreated test plots. The economic benefit after subtracting the cost
of the methyl parathion ranged from a loss of $30.16/acre to a gain of
$653.25/acre.
The results of the yield tests are tabulated in Table 25.
.!/ Wolfenbarger, D. A., M. J. Lukefahr, and H. M. Graham, "LDso Values
of Methyl Parathion and Endrin to Tobacco Budworm and Bollworms
Collected in the Americas and Hypothesis on the Spread of Resistance
in These Lepidopterans to These Insecticides," J. Econ. Entomol.,
66:211-216 (1973).
21 Canerday, T. D., "Response of Bollworm and Tobacco Budworm in Georgia
to Methyl Parathion," J. Econ. Entomol., 67:299 (1974).
3/ Agricultural Statistics, 1973, U.S. Department of Agriculture (1973).
bj Chambers, William, and Daniel Miller, Farmland Industries, Kansas
City, Missouri, personal communication with Mr. David F. Hahlen (1974).
162
-------
Table 25. RESULTS OF METHYL PARATHION APPLIED TO COTTON PESTS
Application
Date
1967
1956
1956
1959
1960
1961
1967
1967
1968
1969
1971
1971
1971
1971
1972
1973
1972
1971
1971
1963
1966
1969
1971
1971
1966
1966
1969
1973
1967
1968
1969
1968
1969
1967
1968
1968
1968
Rate
(Ib Al/acre)
1.25
0.3
0.25
0.25
0.25
0.25
0.25
0.75
1.0
1.0
0.25
0.125
0.25
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
0.75
0.75
0.75
0.75
1.0
1.0
1.0
1.0
1.0
0.75
2.0
2.0
1.25
1.25
1.0
0.75
No.
8
9
9
13
14
13
11
11
6
10
7
7
7
7
10
3
12
7
8
12
9
8
7
7
9
9
7
5
12
4
9
13
16
17
17
6
11
12
17
12
12
8 '
6
6
Yield
increase*
(Ib/acre)
436
1,530
476
68
265
290
487
194
119
775
122
158
97
255
197
34
366
337
499
350
165
547
376
460
177
75
773
220
201
157
801
1,629
867
689
576
219
175
6
845
800
636
419
629
411
Additional
income*
($/acre at
40.7c/lb)
177.45
622.71
193.73
27.67
107.86
118.03
198.21
78.96
48.43
315.42
49.65
64.31
39.48
103.79
80.18
13.84
148.96
137.16
203.09
142.45
67.15
222.63
153.03
187.22
72.04
30.53
314.61
89.54
81.81
63.90
326.01
663.00
352.87
280.42
234.43
89.13
71.23
2.44
343.91
325.60
258.85
170.53
256.00
167.28
Application
cos t (AI
$l/lb + 50C/
application)
14.00
7.20
6.75
9.75
10.50
9.75
8.25
13.75
9.00
15.00
5.25
4.38
5.25
10.50
15.00
4.50
18.00
10.50
12.00
18.00
13.50
12.00
10.50
10.50
13.50
13.50
10.50
7.50
15.00
5.00
11.25
16.25
24.00
25.50
25.50
9.00
16.50
15.00
42.50
30.00
21.00
14.00
9.00
7.50
Economic
benefit*
($)
163.45
615.51
186.98
17.92
97.36
108.28
189.96
65.21
39.43
300.42
44.40
59.93
34.23
93.29
65.18
9.34
130.96
126.66
191.09
124.45
53.65
210.63
142.53
176.72
68.54
17.03
307.11
82.04
66.81
58.90
319.76
647.25
328.87
354.92
208.93
80.13
54.73
(12.56)
301.41
295.60
237.85
156.53
247.00
159.78
Source
a/
b/
*
sJ
d/
e/
LI
£/
h/
a/
163
-------
Table 25. (Continued)
Application
Date
1969
1969
1969
1970
1971
1971
1972
1972
Rate
(Ib Al/acre)
1.5
1.5
1.6
2.0
1.5
1.17
1.5 \
1.5
1.5
1.5
1.5
0.8
1.5
1.5
0.8
1.5
1.5
No.
6
6
8
13
12
6
4
6
6
8
8
8
8
8
8
10
8
Yield
increase*
(Ib/acre)
65
105
65
601
236
115
290
98
(52)
439
596
449
711
614
384
414
364
Additional
income*
($/acre at
40.7c/lb)
26.46
42.74
26.48
244.61
96.05
46.81
118.00
39.89
(21.16)
178.67
242.57
182.74
289.38
249.90
156.29
168.50
148.15
Application
cost (AI
$l/lb + 50C/
application)
12.00
12.00
16.80
31.50
24.00
10.02
8.00
12.00
12.00
16.00
16.00
10.40
16.00
16.00
10.40
20.00
16.00
Economic
benefit*
($)
14.46
30.74
9.68
213.11
72.05
36.79
110.00
27.89
33.16
162.67
226.57
172.34
273.38
233.90
155.89
148.50
132.15
X
,
Source
sJ
i/
U
k/
I/
m/
n/
o/
* Data in parentheses indicate decreases yield, income, and economic benefit.
£/ Cowan, C. B., Jr., and J. W. Davis, "Field Tests With Conventional Low
Volume or Ultra-Low Volume Sprays for Control of the Boll Weevil,
Bollworm, and Tobacco Budwonn on Cotton in 1967," J. Econ. -Entomol.,
61:1115-1116 (1968).
b/ Bost, W. M., Director, Cooperative Extension Service, Mississippi State
University, State College, Mississippi, Summary of Test Results at
Stoneville and Verona, Mississippi, and Costs of Pesticides, personal
letter to Mr. David F. Hahlen.
£/ Cox, John A., Director, Louisiana Cooperative Extension Service, Baton
Rouge, Louisiana, Summary of Test Results in Louisiana, personal
letter to Mr. David F. Hahlen (1974).
d/ Legett, J. E., T. C. Cleveland, and W. P. Scott, "Comparison of Several
Insecticide Combinations for Control of Heliothis spp.," J. Econ.
Entomol.. 65:1182 (1972).
&/ Hopkins, A. R., H. M. Taft, W. James, and C. E. Jernigan, "Evaluation
of Substitutes for DDT in Field Experiments for Control of the Boll-
worm and the Boll Weevil in Cotton, 1967-1969," J. Econ. Entomol.,
63:848-850 (1970).
J:/ Wolfenbarger and McGarr, op. pit. (1971).
£/ McGarr and Wolfenbarger, fig.. ci£. (1969).
164
-------
Table 25. (Continued)
h/ Hanna, R. L., "Field Performance of Chemicals for Control of Tobacco
Budworms, Bollworms, and Carmine Spider Mites on Cotton, College
Station, 1968," Progress Report PR-2671, Texas Agr. Exp. Sta. (1969).
i/ Hanna, R. L., "Field Tests of Chemicals for Control of Tobacco Budworms,
Bollworms, and Carmine Spider Mites on Cotton, College Station,"
Progress Report PR-2842, Texas Agr. Exp. Sta. (1970).
J/ Cowan, C. B., Jr., and J. W. Davis, "Field Evaluation of Insecticides for
Control of the Boll Weevil, Bollworm and Tobacco Budworm on Cotton,
Waco Area, Central Texas, 1968," Progress Report PR-2672, Texas Agr.
Exp. Sta. (1969).
k/ Hanna, R. L., "Field Tests of Chemicals for Control of Tobacco Budworms
and Bollworms on Cotton, College Station," Technical Report 19, pp.
19-22, Texas Agr. Exp. Sta. (1971).
I/ McGarr, R. L., "Field Tests With the Delta-Endotoxin of Bacillus
thuringiensis HD-1 and Chemical Insecticides for Control of the
Tobacco Budworm and Bollworm and the Cotton Leafperforator, 1970
and 1971, Investigations of Chemicals for Control of Cotton Insects
in Texas 1970-1971," Progress Report PR-3082, pp. 1-4, Texas Agr. Exp.
Sta. (1972).
m/ Hanna, R, L., "Field Tests of Chemicals for Control of Tobacco Budworms
and Bollworms on Cotton, College Station, Investigations of Chemicals
for Control of Cotton Insects in Texas, 1970-1971," Progress Report
PR-3084, pp. 22-36, Texas Agr. Exp. Sta. (1972).
n/ Cowan, C. B., Jr., and J. W. Davis, "Chemicals Evaluated in Field Tests
Against Cotton Insects, Investigations of Chemicals for Control of
Cotton Insects in Texas," Technical Report No. 73-20, pp. 9-12, Texas
Agr. Exp. Sta. (1973).
o/ McGarr, R. L., "Field Tests With Bacillus thuringiensis HD-1 and Chemi-
cal Insecticides for Control of the Tobacco Budworm and the Bollworm
at Brownsville, Texas, 1972, Investigations of Chemicals for Control
of Cotton Insects in Texas," Technical Report No. 73-20, pp. 13-17, Texas
Agr. Exp. Sta. (1973).
165
-------
Sorghum
Methyl parathion is registered for control of aphids, greenbugs,
spider mites and the sorghum midge on sorghum. Of these the sorghum
midge and the greenbug are the two most important insects affecting
yield.
Efficacy Against Sorghum Midge Infestation - In the early 1960's the
sorghum midge temporarily caused serious crop losses. However, early
uniform planting has restricted damage from this insect to isolated
late-planted fields (Gate et al., 19731/). Huddleston et al. (1972)!/
reported on tests of insecticides for control of the midge and concluded
that methyl parathion was effective at 0.5 Ib/acre but its phytotoxic
properties limited its use. However, the results of two evaluations
were mixed. Huddleston also reported that yields in a test at Lubbock,
Texas, in 1963, increased from 544 to 3,133 Ib/acre over untreated
checks when increasing amounts of methyl parathion were applied.
Conversely, a similar test conducted at Plainview, Texas, in 1964,
showed that yields compared to an untreated check ranged from a
132 Ib/acre increase to a 330 Ib/acre loss as increasing amounts and
applications of methyl parathion were applied.
Cost Effectiveness of Sorghum Midge Control - The above cited paper by
Huddleston et al., was the only one which compared yields of methyl
parathion treated sorghym plots against an untreated check. The results
of two separate experiments showed yield changes ranging from a loss of
330 Ib/acre to an increase of 3,133 Ib/acre. The price of sorghum
averaged $2.25/cwt in 1972 (Agricultural Statistics, 1973) and the cost
of methyl parathion was $l/lb (Chambers and Miller, 1974). At these
prices and costs, the economic benefits would range from a loss of
$8.43/acre to a gain of $68.49/acre.
These tests are summarized in Table 26.
I/ Cate, J. R., Jr., D. G. Bottrell, and G. L. Teetes, "Management of
the Greenbug on Grain Sorghum. I. Testing Foliar Treatments
of Insecticides Against Greenbugs and Corn Leaf Aphids," J. Econ.
Entorool., 66:945-951 (1973).
2/ Huddleston, E. W., D. Ashdown, B. Maunder, C. R. Ward, G. Wilde, and
C. E. Forehand, "Biology and Control of the Sorghum Midge. I.
Chemical and Cultural Control Studies in West Texas," J. Econ.
Entomol., 65:851-855 (1972).
166
-------
Table 26. RESULTS OF METHYL PARATHION APPLIED TO THE SORGHUM MIDGE
Date
1963
1964
Application
Rate
(Ib Al/acre)
0.5
1.0
0.5
1.0
0.5
1.0
0.5
0.5
No.
1
1
2
2
1
1
2
2
Yield
increase*
(Ib/acre)
544
1,123
2,372
3,133
132
242
(330)
(132)
Additional
income*
($/acre at
$2.25/ewt)
12.24
25.27
53.37
70.49
2.97
5.45
(7.43)
(2.97)
Application
cost (AI
$l/lb + 50c/
application)
1,
1,
2,
3,
1,
1.
2.
50
50
00
00
00
50
00
2.00
Economic
benefit*
($) Source
11.74 a/
24.27
52.37
68.49
2.47
4.45
(8.43)
(4.97)
* Data in parentheses indicate decreases in yield, income, and economic
benefit.
aj Huddleston et al., op_. cit. (1972).
Greenbug
Efficacy Against Greenbug Infestation - Although there are numerous
insects affecting sorghum, perhaps the greenbug causes the greatest
damage. Prior to 1968, the greenbug had been found mostly in small
grains such as wheat, barley, and oats. However, in 1968 a new bio-
type emerged and began infesting sorghum. Ward et al. (1970)I/ noted
that in 1968, 7.3 million acres became infested resulting in a pro-
duction loss estimated at $20 million. Gate et al. (1973) reported
that the Grain Sorghum Producers Board estimated that $14 million was
spent for control of grain sorghum pests in 1970 compared with onlyv
$100,000 spent prior to 1968.
Methyl parathion gives good control of greenbugs. Daniels (1971)2/
treated sorghum with 0.5 Ib of methyl parathion per acre at Bushland,
Texas, in 1968. Greenbug control was 94% at the end of a week and within
3 weeks live greenbugs disappeared. During this time, plants without
treatment died 14 days after greenbug populations reached 13,500/plant.
Yields increased 5%. In a similar test in 1969, greenbug reduction
averaged 90% over a 29-day period.
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).
2/ Daniels, N. E., "Insecticidal Greenbug Control in Grain Sorghum, Research
on Grain Sorghum*Insects and Spider Mites in Texas," Progress Report
PR-2868, pp. 16-20, Texas Agr. Exp. Sta. (1971).
167
-------
Gate et al. (1973) also reported 95% control after 21 days in tests
conducted in Lubbock County, Texas, in 1970. Teetes et al. (1973)I/ re-
ported 95% control of greenbugs 14 days after application of 0.25 Ib/acre
of methyl parathion in tests at Lubbock, Texas, in 1972. When applied
at 0.5 Ib/acre, 96% control was achieved in 14 days.
Although methyl parathion controls greenbugs, it appears to be
phytotoxic to sorghum and can, under some conditions, result in yield
reductions. Meisch et al. (1970)2/ evaluated insecticides for phyto-
toxicity and found methyl parathion caused severe leaf damage and re-
duced yields on five of six varieties of sorghum when applied at 1.0
Ib/acre and reduced yields on four of the six when applied at 0.5 Ib/acre,
Cate et al. (1973) found that EC methyl parathion burned the top leaves
but the encapsulated formulation did not cause phytotoxicity.
Cost Effectiveness of Greenbue Control - The results of several tests
in Texas show that yield changes varied from a loss of 563 Ib/acre to
a gain of 605 Ib/acre when methyl parathion was used to control the
greenbug.
The price of sorghum averaged $2.25/cwt in 1972 (Agricultural
Statistics, 1973) and the cost of methyl parathion was $l/lb (Chambers
and Miller, 1974). At these prices and costs, the economic benefits
would range from a loss of $13.67/acre to a gain of $13.11/acre for the
use of methyl parathion to control the greenbug.
These tests are summarized in Table 27.
Wheat
The greenbug has been regarded as the most destructive of the
aphids infecting small grains since its introduction into North America
in the Nineteenth Century.
if Teetes, G. L., G. W. Brothers, and C. R. Ward, "Insecticide Screening
for Greenbug Control and Effect on Certain Beneficial Insects," Prog-
ress Report PR-3166, Texas Agr. Exp. Sta. (1973).
2J Meisch, N. V., George L. Teetes, N. M. Randolph, and A. J. Bockholt,
"Phytotoxic Effects of Insecticides on Six Varieties of Grain Sorghum,"
J. Egon. Entomol.. 63:1516-1517 (1970).
168
-------
Tablet 27. RESULTS OF METHYL PARATHION APPLIED TO THE SORGHUM GREENBUG
VIA"
Date
1968
1970
1969
Application
(Ib Al/acre)
1972
1968
0,
0,
0,
5
5
25
1.0
0.5
1.0
0.5
1.0
0.5
1.0
0.5
1.0
0.5
1.0
0.5
0.25
0.5
0.5
Yield
increase*
(Ib/acre)
(413)
317
283
(563)
147
(147)
(292)
(560)
(490)
(488)
(478)
(407)
(115)
450
605
140
(166)
327
Additional
income* at
$2.25/cwt
($/acre)
(9.29)
7.13
6.37
(12.67)
3.31
(3.31)
(6.57)
(12.60)
(11.03)
(10.98)
(10.76)
(9.16)
(2.59)
10.13
13.61
3.15
(3.74)
7.36
Application
cost (AI
$l/lb + 50$/
application)
,00
,00
0.75
1,
1.
1.
1,
1.
1,
1,
2,
1.
1,
1,
,50
.00
,50
.00
.50
.00
.50
.00
.50
.00
,50
1.00
0.75
1.00
1.00
Economic
benefit*
($)
(10.29)
6.13
5.62
(14.17)
2.31
(4.81)
(7.57)
(14.10)
(12.03)
(12.48)
(11.86)
(10.56)
(3.59)
8.63
12.61
2.40
(4.74)
6.36
Source
a/
W
b/
c/
I/
e/
* Data in parentheses indicate decreases, yield, income, and economic
benefit.
aj Ward et al., op. cit. (1970).
b/ Gate et al., op_. cit. (1973).
cj Meisch et al., op. cit. (1970).
d/ Teetes et al., op. cit. (1973).
ef Daniels, N. E., op_. cit. (1971).
Efficacy Against Greenbug Infestation - As a result of a heavy infestation
of greenbugs in Texas in 1961, Daniels (1962)I/ evaluated several insecticides
for their control on wheat crops. These tests at Bushland, Texas, in 1961
resulted in satisfactory control with methyl parathion. In two experiments,
an average of 94% reduction was achieved in both tests. Yields increased
7 and 11.73 bushels per acre, respectively.
I/ Daniels, N. E., "Insecticidal Control of the Greenbug," Progress Report
PR-2247, Texas Agr. Exp. Sta. (1962).
169
-------
Ward et al. (1972)1.' screened various insecticides at Clovis, New
Mexico, in 1969 and reported a 99% reduction in'greenbugs after 14 days
with methyl parathion. Yields increased by 400 Ib/acre or 6.67 bushels.
Cost Effectiveness of Greenbug Control - Yield increases based upon the
three tests reported above varied from 6.67 to 11.73 bushels per acre.
At a price of $1.67/bushel for wheat in 1972 (Agricultural Statistics,
1973) and a cost of $l/lb for methyl parathion (Chambers and Miller,
1974), the economic benefit would range from $10.64 to $19.09/acre from
control of the greenbug on wheat.
These are summarized in Table 28.
-»c
Table 28. RESULTS OF METHYL PARATHION APPLIED TO THE WHEAT GREENBUG
Additional Application
Yield increase cost (AI Economic
Application increase at $1.67/bu $l/lb + 50
-------
Efficacy Against Pest Infestation - Teetes et al. (1968)1/ tested
several insecticides at College Station, Texas, in 1967. Methyl
parathibn at 1.0 Ib/acre effectively reduced the larvae and increased
yields by 65% over an untreated check. In a similar test at McGregor,
Texas, three applications resulted in a greater reduction of insects.
A second test at McGregor showed greater yields with multiple appli-
cations at 5-day intervals than 15-day intervals.
Teetes et al. (1969).?_/ repeated tests at McGregor, Texas, and
achieved a 54% reduction in the sunflower moth and a 256% increase
in yield with two applications of 0.5 Ib/acre methyl parathion. With
three applications at this rate, a 91% reduction in moths was achieved
with a corresponding 412% increase in yield. Similar results were
achieved in experiments at McGregor in 1969 (Teetes et al., 19713/).
Carlson (1971)A/ tested several insecticides at Davis, California
in 1968 and in two experiments found that methyl parathion gave 79% and
97% reduction of seed damage with corresponding increases of 611 and 227
Ib of seed per acre.
Cost Effectiveness of Pest Control - The results of the various tests
comparing yield increases with methyl parathion application rates show
increases varying from a loss of 21 Ib/acre to a gain of 792 Ib/acre.
The prices for sunflower seeds are $7.50/cwt (Kantack, 1974A/) and
methyl parathion costs are $l/lb (Chambers and Miller, 1974). At these
prices and costs, the economic benefits vary from a loss of $2.58/acre
to a gain of $57.90/acre from the use of methyl parathion to control the
sunflower moth.
The test results are summarized in Table 29.
_!/ Teetes, G. L., and N. M. Randolph, "Chemical Control of the Sunflower
Moth on Sunflowers." J. Econ. Entomol., 61:1344-1347 (1968).
2f Teetes, G. L., and N. M. Randolph, "Effects of Pesticides and Dates
of Planting Sunflowers on the Sunflower Moth," J. Econ. Entomol.,
64:124-126 (1971).
_3/ Carlson, E. C., "New Insecticides to Control Sunflower Moth," J. Econ.
Entomol., 64:208-209 (1971).
4/ Kantack, B. H., Extension Entomologist Cooperative Extension Service,
Brookings, South Dakota, Summary of Tests, personal correspondence to
Mr. David F. Hahlen (1974).
171
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Table 29. RESULTS OF METHYL PARATHION APPLIED TO THE SUNFLOWER MOTH
Date
1967
Application
Rate
(Ib Al/acre) No,
1,
1,
1,
1,
1,
1,
1,
1,
1,
1,
1,
1,
1.0
0
0
0
0
0
1.0
0.
0.
0,
1,
1,
1.0
1.5
1.5
1
1
2
3
1
2
3
3
3
3
1
1
1
1
2
3
2
2
3
1
1
1
Yield
increase*
(Ib/acre)
382
50
150
200
(21)
158
142
300
' 148
80
(17)
(12)
75
146
490
792
686
316
507
566
611
227
Additional
increase*
($/acre at
$7.50/cwt)
28.65
3.75
11.25
15.00
(1.58)
11.85
10.65
22.50
11.10
6.00
(1.28)
(0.90)
5.63
10.95
36.75
59.40
51.45
23.70
38.03
42.45
45.83
17.03
Application
cost (AI
$l/lb + 50C/
application)
1,
1.
3.
50
50
00
4.50
.50
.00
.50
.50
4.50
4.50
.50
.50
.50
.50
.00
.00
.00
.00
1,
3,
4,
4,
1,
1,
1,
1,
2,
3,
2,
3.
4.50
1.
2,
50
00
2.00
Economic
benefit*
($) Source
27.15 &J
2.25
8.25
10.50
(3.08)
8.85
1.15
18.00
6.60
1.50
(2.78)
(2.40)
4.13
9.45
34.75 b/
56.40
49.45
22.70 c/
33.53
40.95
43.83 d/
15.03
* Data in parentheses indicate decreases in yield, income, and economic
benefit. ...-.-,
a/ Teetes et al., op_. cit. (1968). '-•&'*
b/ Teetes, G. L., and N. M. Randolph, "Chemical Control and Cultural Control
of the Sunflower Moth in Texas," J. Econ. Entomol.. 62:1444-1446 (1969).
cj Teetes, G. L. and N. M. Randolph, "Effects of Pesticides and Dates of
Planting Sunflowers on the Sunflower Moth," J. Econ. Entomol.. 64:124-
126 (1971).
,d/ Carlson, E. C., "New Insecticides to Control Sunflower Moth," J. Econ.
Entomol.. 64:208-229 (1971).
172
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'* VS. GOVERNMENT PRINTING OFFICE 1975- 210-810/24
— 176
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