malathion (Cythion) Chemical Profile 4/85
CHEMICAL NAME: O,O-dimethyl phosphorodithioate of diethyl mercapto-
DEC INGRED. CODE:
TRADE NAME(S): Cythion, Malathion ULV Concentrate (56)
FORMULATION(S): Emulsifiable concentrate, oil solutions, wettable
powder, dust, ULV concentrate (56).
TYPE: Organophosphate insecticide
BASIC PRODUCER(S): American Cyanamid Co.
Agricultural Research Div.
P. O. Box 400
Princeton, NJ 08540
STATUS: General use
PRINCIPAL USES: Malathion controls a wide variety of insects including
aphids, spider mites, scale insects, house fly, and mosquitoes as well
as a large number of other sucking and chewing insects attacking fruits,
vegetables, ornamentals and stored products. Malathion is also used for
adult mosquito control in public health programs. Its use is
particularly indicated where a high degree of safety to mammals is
desired - a tolerance of 135 ppm for forage, grass and green hay allows
malathion to be applied on the same day as grazed or harvested.
Malathion ULV Concentrate is registered for ULV aerial application
to alfalfa, clover, pasture and range grasses, nonagricultural land,
cereal crops, cotton, safflower, soybeans, sugar beets, corn, beans,
blueberries for the control of many insects at rates of 4 to 16 ounces
Cythion or Fyfanon or Emmatos extra is a low-odor product
manufactured by patented processes. In the U.S. this is the only grade
registered for use on stored grain, recommended for use inside homes,
and accepted for use on humans (56).
Important Pests Controlled: Aphids, mites, scale, flies, leafhoppers,
leafminers, thrips, loopers, pear psylla, mealybugs, Japanese beetles,
lygus bugs, spittlebugs, corn earworms, chinchbugs, grasshoppers,
armyworms, bollweevils, bollworms, lice , ticks, ants, spiders,
mosquitoes, and many others (8a).
II. PHYSICAL PROPERTIES
MOLECULAR FORMULA: C10 H19 06 P S2 (62)
MOLECULAR WEIGHT: 330.3 (62)
PHYSICAL STATE: Clear amber liquid (technical grade, c. 95% pure)
MELTING POINT: 2.85 C (technical grade) (62)
BOILING POINT: 156-157 C/0.7 mmHg (technical grade) (62)
VAPOR PRESSURE: 5.3 mPa at 30 C (technical grade) (62)
SOLUBILITY: 145 mg/l water at room temperature (technical grade)
III. HEALTH HAZARD INFORMATION
OSHA STANDARD: 15 mg/m3 averaged over an 8-hour work shift (14)
NIOSH RECOMMENDED LIMIT: 15 mg/m3 averaged over a work shift of up to
10 hours per day, 40 hrs. per week (14).
ACGIH RECOMMENDED LIMIT: TWA (Time Weighted Average) = 10 mg/m3;
skin notation (15c).
A. ACUTE TOXICITY
DERMAL: LD50 (24hr) = 4100 mg/kg (rabbit) (62)
ORAL: LD50 = 2800 mg/kg (rat) (62)
LD50 (rat) = 1375 mg/kg (male); 1000 mg/kg (female)
EYES: Workers exposed to 84.8 mg/m3 experienced moderate
eye irritation (15b).
B. SUBACUTE AND CHRONIC TOXICITY:
Malathion has been fed to rats for 104 weeks at levels as high as
5000 ppm in the diet with no gross effects (56).
In 1.75 yr trials rats receiving 100 mg tech./kg diet showed normal
weight gain (62).
There was no effect found on blood cholinesterase when malathion
was fed to human volunteers for 47 days at the rate of 16 mg/man/day.
Volunteers dosed dermally showed no change of blood cholinesterase or
other injury while exceeding an average of 47 mg/man/day and a maximum
of 220 mg/man/day. The actual absorption was probably at least double
these amounts (15b).
IV. ENVIRONMENTAL CONSIDERATIONS
Some hazard to birds, fish, and beneficial insects, but little to
mammals. Hazardous to honey bees. Biological magnification unlikely.
Injury reported on several kinds of fruit, vegetables, and ornamentals
LC50 (5-day) is: for bobwhite quail 3497 mg/kg diet; for ring-necked
pheasant 4320 mg/kg diet (62).
LC50 (96-hr) is: for bluegill 0.103 mg/l; for largemouth bass
0.285 mg/l. Topical toxicity for honeybees, LD50 0.71 ug/bee (62).
Approximate Residual Period: 5-10 days on plants; unexposed surfaces
1 month; short residual in soil (1).
V. EMERGENCY AND FIRST AID PROCEDURES
The chemical information provided below has been condensed from
original source documents, primarily from "Recognition and Management
of Pesticide Poisonings", 3 rd ed. by Donald P. Morgan, which have been
footnoted. This information has been provided in this form for your
convenience and general guidance only. In specific cases, further
consultation and reference may be required and is recommended. This
information is not intended as a substitute for a more exhaustive review
of the literature nor for the judgement of a physician or other trained
If poisoning is suspected, do not wait for symptoms to develop.
Contact a physician, the nearest hospital, or the nearest Poison Control
FREQUENT SYMPTOMS AND SIGNS OF POISONING BY ORGANOPHOSPHATE PESTICIDES
Symptoms of acute poisoning develop during exposure or within 12
hours (usually within four hours) of contact. HEADACHE, DIZZINESS,
WEAKNESS, INCOORDINATION, MUSCLE TWITCHING, TREMOR, NAUSEA, ABDOMINAL
CRAMPS, DIARRHEA, and SWEATING are common early symptoms. Blurred or
dark vision, confusion, tightness in the chest, wheezing, productive
cough, and PULMONARY EDEMA may occur. Incontinence, unconsciousness
and convulsions indicate very severe poisoning. SLOW HEARTBEAT,
salivation, and tearing are common. TOXIC PSYCHOSIS, with manic or
bizarre behavior, has led to misdiagnosis of acute alcoholism. Slowing
of the heartbeat may rarely progress to complete sinus arrest.
RESPIRATORY DEPRESSION may be fatal. Continuing daily absorption of
organophosphate at intermediate dosage may cause an INFLUENZA-LIKE
ILLNESS characterized by weakness, anorexia, and malaise (25).
SKIN CONTACT: Bathe and shampoo victim with soap and water if
there is any chance that skin and hair are contaminated (25).
INGESTION: If victim is alert and respiration is not depressed,
give Syrup of Ipecac, followed by 1-2 glasses of water to induce
vomiting. Adults (12 years and over): 30 ml; children: 15 ml (25).
INHALATION: If a person breathes in large amounts of malathion,
move the exposed person to fresh air at once. If breathing has stopped,
perform artificial respiration. Keep the affected person warm and at
rest. Get medical attention as soon as possible (14).
EYE CONTACT: Wash eyes immediately with large amounts of water,
lifting the lower and upper lids occasionally. Get medical attention
NOTES TO PHYSICIAN:
Administer ATROPINE SULFATE intravenously, or intramuscularly, if IV
injection is not possible.
In MODERATELY SEVERE poisoning: Adult dosage: 0.4-2.0 mg repeated
every 15 minutes until atropinization is achieved: tachycardia (pulse
of 140 per minute), flushing, dry mouth, dilated pupils. Maintain
atropinization by repeated doses for 2-12 hours or longer depending on
severity of poisoning.
Dosage for children under 12 years: 0.05 mg/kg body weight, repeated
every 15 minutes until atropinization is achieved. Maintain
atropinization with repeated dosage of 0.02-0.05 mg/kg.
SEVERELY POISONED individuals may exhibit remarkable tolerance to
atropine; two or more times the dosages suggested above may be needed.
Administer PRALIDOXIME (Protopam (TM)-Ayerst, 2-PAM) in cases of severe
poisoning in which respiratory depression, muscle weakness and
twitchings are severe.
Adult dosage: 1.0 gm intravenously at no more than 0.5 gm per minute.
Child's dose (under 12 years): 20-50 mg/kg (depending on severity of
poisoning) intravenously, injecting no more than half the total dose
Dosage of pralidoxime may be repeated in 1-2 hours, then at 10-12 hour
intervals if needed. In very severe poisonings, dosage rates may be
VI. FIRE AND EXPLOSION INFORMATION
GENERAL: Toxic gases and vapors (such as sulfur dioxide, phosphoric
acid mist, and carbon monoxide) may be released in a fire involving
Compatible with most insecticides and fungicides except alkaline
materials (1). Contact with strong oxidizers may cause fires and
explosions (14). When mixed with alkaline materials initial kills are
satisfactory, but residual toxicity may be decreased (8a).
VIII. PROTECTIVE MEASURES
STORAGE AND HANDLING: Store where possible leakage from containers
cannot endanger the worker. Maintain regular inspection of containers
for any leakage (34d).
Harmful by swallowing, inhalation or skin contact. Avoid breathing
spray mist. Avoid contact with skin. Wash thoroughly after handling.
Change contaminated clothing. Do not contaminate food or feed products
PROTECTIVE CLOTHING: Employees should be provided with and required to
use impervious clothing, gloves, face shields (eight-inch minimum), and
other appropriate protective clothing necessary to prevent repeated or
prolonged skin contact with malathion (14).
PROTECTIVE EQUIPMENT: Respirators may be used when engineering and
work practice controls are not technically feasible, when such controls
are in the process of being installed, or when they fail and need to be
supplemented. Respirators may also be used in emergency situations.
The only respirators permitted are those that have been approved by the
Mine Safety and Health Administration, or by the National Institute for
Occupational Safety and Health (14).
IX. PROCEDURES FOR SPILLS AND LEAKS
IN CASE OF EMERGENCY, CALL, DAY OR NIGHT
PESTICIDE TEAM SAFETY NETWORK/CHEMTREC
Persons not wearing protective equipment and clothing should be
restricted from areas of spills or leaks until cleanup has been
If malathion is spilled or leaked, the following steps should be
1. Ventilate area of spill or leak.
2. Collect for reclamation or absorb in vermiculite, dry sand,
earth, or a similar material.
Waste disposal method:
Malathion may be disposed of by absorbing in vermiculite, dry
sand, earth or a similar material and disposing in sealed containers in
a secured sanitary landfill (14).
X. LITERATURE CITED
1. Harding, W.C. 1979. Pesticide profiles, part one: insecticides
and miticides. Univ. Maryland, Coop. Ext. Serv. Bull. 267.
8a. Thomson, W. T. 1976. Agricultural chemicals - book 1:
insecticides, acaricides, and ovicides. Revised ed. Thomson
Publ., Indianapolis, IN. 232 pp.
14. U. S. Department of Health and Human Services, National Institute
for Occuptational Safety and Health. 1981. Occupational
health guidelines for chemical hazards. F. W. Mackinson, R.
S. Stricoff, L. J. Partridge, Jr., and A. D. Little, Inc.,
eds. DHHS (NIOSH) Publ. No. 81-123. Washington, DC.
15b. American Conference of Governmental Industrial Hygienists. 1971.
Documentation of the threshold limit values for substances in
workroom air with supplements for those substances added or
changed since 1971, 3rd ed., 4th printing (1977). Cincinnati,
OH. 484 pp.
15c. American Conference of Governmental Industrial Hygienists. 1984.
TLVs: threshold limit values for chemical substances and
physical agents in the work environment and biological exposure
indices with intended changes for 1984-85. Cincinnati, OH.
25. Morgan, D.P. 1982. Recognition and management of pesticide
poisonings, 3rd ed. U.S. Environmental Protection Agency,
Washington, DC. 120 pp.
34d. New York State Department of Health, Bureau of Toxic Substances
Management. 1981. Chemical fact sheet: malathion. Albany,
56. Farm Chemicals Handbook, 70th ed. 1984. R. T. Meister, G. L.
Berg, C. Sine, S. Meister, and J. Poplyk, eds. Meister
Publishing Co., Willoughby, OH.
62. The Pesticide Manual: A World Compendium, 7th ed. 1983. C.R.
Worthing, ed. The British Crop Protection Council, Croydon,
England. 695 pp.