The information in this profile may be out-of-date. It was last revised in 1996. EXTOXNET no longer updates this information, but it may be useful as a reference or resource.

Please visit the National Pesticide Information Center (NPIC) to find updated pesticide fact sheets. If you don't find a fact sheet related to your question, feel free to call 1-800-858-7378. NPIC is open five days a week from 8:00am to 12:00pm Pacific Time.


Extension Toxicology Network

Pesticide Information Profiles

A Pesticide Information Project of Cooperative Extension Offices of Cornell University, Oregon State University, the University of Idaho, and the University of California at Davis and the Institute for Environmental Toxicology, Michigan State University. Major support and funding was provided by the USDA/Extension Service/National Agricultural Pesticide Impact Assessment Program.

EXTOXNET primary files maintained and archived at Oregon State University

Revised 9/93.


TRADE OR OTHER NAMES: Trade names include AC 3422, Alkron, Alleron, Aphamite, Corothion, E-605, ENT 15108, Ethyl parathion, Etilon, Fosferno 50, Niran, Orthophos, Panthion, Paramar, Paraphos, Parathene, Parawet, Phoskil, Rhodiatox, Soprathion, Stathion and Thiophos. The common name thiophos is used in the former USSR.

REGULATORY STATUS: Because of its high toxicity and risks of exposure to agricultural workers and to birds, and in response to the manufacturers' request, EPA in January 1992 announced the cancellation of all uses of parathion on fruit, nut and vegetable crops. The only uses retained are those on alfalfa, barley, corn, cotton, sorghum, soybeans, sunflowers and wheat. Further, to reduce exposure of agricultural workers, parathion may be applied to these crops only by commercially certified aerial applicators and treated crops may not be harvested by hand. EPA intends to cancel all uses of parathion in the near future (12, 13).
Parathion is one of the most acutely toxic pesticides registered by the EPA. Because of its highly toxic nature, parathion is classified as a Restricted Use Pesticide (RUP) (1, 3). RUPs may be purchased and used only by certified applicators. Products containing parathion must bear the signal word "Danger" (3).

CHEMICAL CLASS: organophosphate insecticide

INTRODUCTION: Parathion is a broad spectrum, organophosphate pesticide used to control many insects and mites (5, 8). It has non-systemic, contact, stomach and fumigant actions (5, 8). It has a wide range of applications on many crops against numerous insect species (1). Parathion is available in dust, emulsion concentrate, granular, ULV liquid, and wettable powder formulations (3).
Parathion is one of a class of insecticides referred to as organophosphates. These chemicals act by interfering with the activities of cholinesterase, an enzyme that is essential for the proper working of the nervous systems of both humans and insects. Please refer to the Toxicology Information Brief on cholinesterase-inhibition for a more detailed description of this





Parathion hydrolyzes slowly at pH 7 or below, but is otherwise stable at normal temperatures (3). At temperatures above 120 degrees C, parathion decomposes and may develop enough pressure to cause containers to explode. Thermal decomposition may release toxic gases such as diethylsulfide, sulfur dioxide, carbon monoxide, carbon dioxide, phosphorus pentoxide, and nitrogen oxides (3). Parathion poses a fire and explosion hazard in the presence of strong oxidizers. It may attack plastics, rubber and coatings (11). Persons who work with organophosphate materials for long periods of time should have frequent blood tests of their cholinesterase levels. If the cholinesterase level falls below a critical point, no further exposure should be allowed until it returns to normal (15).

Protective clothing must be worn when handling fenthion. Before removing gloves, wash them with soap and water. Always wash hands, face and arms with soap and water before smoking, eating or drinking. After work, remove all work clothes and shoes. Shower with soap and water. Wear only clean clothes when leaving the job. Wash contaminated clothing and equipment with soap and water after each use. Keep contaminated work clothes separate from regular laundry.

The National Fire Protection Agency ratings for parathion include: A. health: 4 = a few whiffs of the fumes could prove fatal; normal fire fighting gear is inadequate to protect against any exposure to the skin. B. flammability: 1 = solids which must be preheated to burn, but which are combustible. It may be dangerous to use water to extinguish burning parathion. C. reactivity: 2 = normally unstable materials which will react violently (with water). Also, it is potentially explosive when mixed with water (18).

Physical Properties:

Exposure Guidelines:


Miles, Inc.
Crop Protection and Animal Health Div.
PO Box 4913
Kansas City MO 64120


(1) Meister, R.T. (ed.) 1987. Farm Chemicals Handbook. Willoughby, OH: Meister Publishing Co.

(2) Hayes, W.J. and E.R. Laws (ed.). 1990. Handbook of Pesticide Toxicology, Vol. 3, Classes of Pesticides. Academic Press, Inc., NY.

(3) Meister, R.T. (ed.). 1992. Farm Chemicals Handbook '92. Meister Publishing Company, Willoughby, OH.

(4) Tucker, Richard. 1970. Handbook of toxicity of pesticides to wildlife. USDI Fish & Wildlife Service.

(5) Worthing, C.R. (ed.). 1987. The pesticide manual: A world compendium. 8th Ed. The British Crop Protection Council. Croydon, England.

(6) Hayes, Wayland, Jr. 1982. Pesticides studied in man. Baltimore, MD: Williams & Wilkins.

(7) Kearney, P.C. & D.D. Kaufman (eds.). 1975. Herbicides: chemistry, degradation, and mode of action. 2nd Ed. Vol. 1 & 2. New York: M. Dekker.

(8) Hartley, D. and H. Kidd, (eds.) 1983. The agrochemicals handbook. Nottingham, England: Royal Society of Chemistry.

(9) U. S. Department of Agriculture, Soil Conservation Service. 1990 (Nov.). SCS/ARS/CES Pesticide Properties Database: Version 2.0 (Summary). USDA - Soil Conservation Service, Syracuse, NY.

(10) Howard, P.H. (ed.). 1989. Handbook of Environmental Fate and Exposure Data for Organic Chemicals, Vol. III: Pesticides. Lewis Publishers, Chelsea, MI.

(11) Occupational Health Services, Inc. 1991 (Feb. 25). MSDS for Parathion. OHS Inc., Secaucus, NJ.

(12) US Environmental Protection Agency. 1992 (Feb. 4). Ethyl Parathion, Correction to the Amended Cancellation Order. OPP, USEPA, Washington DC.

(13) _____. 1991 (Dec.). Notice of Voluntary Cancellation of Parathion Registrations Except for Use on Field Crops. US EPA, Washington, DC.

(14) Hallenbeck, W.H. & K.M. Cunningham-Burns. 1985. Pesticides and human health. New York: Springer-Verlag.

(15) Cheminova Agro A/S. 1991 (June 11). Material Safety Data Sheet : Dimethoate. Cheminova, Lemvig, Denmark.

(16) TOXNET. 1985. National library of medicine's toxicology data network. Hazardous Substances Databank. Public Health Service. National Institute of Healtyh. U.S. Department of Health and Human Services. Bethesda, MD: NLM.

(17) Gosselin, R.E. 1984. Clinical toxicology of commercial products. 5th Ed. Baltimore, MD: Williams & Wilkins.

(18) National Fire Protection Association (NFPA). 1978. Fire Protection Guide. Hazardous Materials.

(19) Windholz, M. (ed.) 1976. The Merck Index: an encyclopedia of chemicals and drugs. 9th Ed. Rahway, NJ: Merck.

DISCLAIMER: The information in this profile does not in any way replace or supersede the information on the pesticide product label/ing or other regulatory requirements. Please refer to the pesticide product label/ing.