Parathion (Ethyl) - Chemical Profile 4/85
CHEMICAL name: O,O-diethyl O-p-nitrophenyl phosphorothioate (56)
DEC INGRED. CODE:
TRADE name(S): Niran, Phoskil (56)
FORMULATION(S): Emulsion concentrates, wettable powders, granules,
dusts, aerosols, oil spray (56).
TYPE: Organophosphate insecticide-miticide
BASIC PRODUCER(S): Monsanto Agricultural Products Co., a unit of
800 N. Lindbergh Blvd.
St. Louis, MO 63166
STATUS: Restricted use
PRINCIPAL USES: Has a wide range of application on many crops
against numerous insect species (56).
Important Pests Controlled: Codling moths, scale, aphids, mealy bugs,
leafhoppers, mosquitoes, grasshoppers, mites, thrips, leafminers, plum
curculio, crickets, pear psylla, spittlebugs, armyworms, corn borers,
corn earworms, and many others (8a).
Shows some fumigant action (8a).
II. PHYSICAL PROPERTIES
MOLECULAR FORMULA: C10 H14 NO5 P S (62)
MOLECULAR WEIGHT: 291.3 (62)
PHYSICAL STATE: Pale yellow liquid (pure compound); brown
liquid (technical product) (62).
ODOR: Garlic-like (technical product) (62)
BOILING POINT: 157-162 C/0.6 mmHg (pure compound) (62)
VAPOR PRESSURE: 5.0 mPa at 20 C (pure compound) (62)
SOLUBILITY: 24 mg/l water at 25 C (pure compound) (62)
III. HEALTH HAZARD INFORMATION
OSHA STANDARD: 0.1 mg/m3 averaged over an 8-hr work shift (14)
NIOSH RECOMMENDED LIMIT: 0.05 mg/m3 (14)
ACGIH RECOMMENDED LIMIT: TWA (Time Weighted Average): 0.1 mg/m3;
STEL (Short Term Exposure Limit): 0.3 mg/m3
(deleted) skin notation (15c).
A. ACUTE TOXICITY
DERMAL: LD50 (rat) = 21 mg/kg (male); 6.8 mg/kg (female) (62).
LD50 = 55 mg/kg (rat) (56)
ORAL: LD50 (rat) = 13 mg/kg (male); 3.6 mg/kg (female) (62).
INHALATION: Although there are no documented deaths due
to inhalation of parathion, an estimated 10 to 20
mg may cause death (34e).
EYES: Contact with concentrated solutions can represent a
real threat to life (34e).
B. SUBACUTE AND CHRONIC TOXICITY:
Parathion has caused birth defects in animals. Whether it does so
in humans is unknown (34e). Brown and Bush (1950) in the U.S. found
parathion in a concentration range of 0.1-0.8 mg/m3 in a processing
plant. Cholinesterase determinations on blood from exposed workers
showed decreased activity (15b). Arterberry, et al (1961) found a
slight depression in cholinesterase at a urinary p-nitrophenol
excretion of about 2 mg/liter in workers repeatedly exposed. Depending
on the circumstances, such a concentration of p-nitrophenyl in the
urine could result from inhalation of as little as 0.2 mg/m3 of
parathion in the air (15b).
Edson (1964) found that doses of 1.47 mg/man/day produced no
effect in volunteers, while a dosage of 5.46 produced moderate
depression of blood cholinesterase. In corresponding studies in rats,
Edson found that rats tolerated for 84 days a dosage corresponding to
0.42 mg/man/day, but showed a 46% fall in red blood cell cholinesterase
when given a dosage equivalent to 4.2 mg/man/day (15b).
IV. ENVIRONMENTAL CONSIDERATIONS
Moderately hazardous to birds, fish and beneficial insects.
Hazardous to honey bees. Biological magnification unlikely. Injury
has been reported on several varieties of apples and certain
ornamentals. Check label (1).
Approximate Residual Period: 3-7 days on plant surfaces; short
residual on 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", 3rd 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 sub-
stitute for a more exhaustive review of the literature nor for the
judgement of a physician or other trained professional.
If poisoning is suspected, do not wait for symptoms to develop.
Contact a physician, the nearest hospital, or the nearest Poison
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: Move to fresh air. Give artificial respiration as
required. Seek medical attention (34e).
EYE CONTACT: Wash eyes with water for at least 15 minutes. Seek
medical attention (34e).
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
SEVERELY POISONED individuals 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
Noncombustible. Heating causes breakdown to poisonous and
suffocating fumes of nitrogen, phosphorus or sulphur (34e).
Incompatible with alkaline materials (1). Incompatible with
oxidizers such as chlorine, dichromate and permanganate (34e).
Compatible with other insecticides and fungicides (8a).
VIII. PROTECTIVE MEASURES
STORAGE AND HANDLING: Store where possible leakage from containers
will not endanger the worker. Maintain regular inspection of
containers for leakage (34e). Extremely toxic to warm-blooded animals
through inhalation, skin absorption, and ingestion. Do not store
parathion near food or feed products. Do not heat product above 200 F
PROTECTIVE CLOTHING: Safety glasses, rubber gloves and impervious
clothing should be worn while using this insecticide (34e).
PROTECTIVE EQUIPMENT: For levels up to 0.5 mg/m3 use a half-mask
pesticide respirator or a Type-C supplied-air respirator, demand type
with a half-mask facepiece. For levels up to 2.5 mg/m3 wear a full
face gas mask (chin, chest, or back-mounted type) or a Type-C
supplied-air respirator, demand type with full facepiece. Up to 50
mg/m3 wear a Type-C supplied air respirator, continuous flow type with
full facepiece or suit or pressure-demand type respirator with full
facepiece and impervious plastic shroud. In cases of emergency
(including situations of entry into vessels, bins or other containers
which are probably contaminated with parathion) wear a self-contained
breathing apparatus with positive pressure in full facepiece or
combination supplied-air respirator, pressure demand type with
auxiliary, self-contained air supply (34e).
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 parathion 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:
Parathion may be disposed of by absorbing it 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.
34e. New York State Department of Health, Bureau of Toxic Substances
Management. 1981. Chemical fact sheet: parathion. 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.