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Protective measures that have been applied concerning the chemical
Annex 1 - further information on the substance
Annex 2 - details on reported control actions
Annex 3 - list of designated national authorities
Annex 4 - references

Published: June 97



Name Other names/




13171-21-6 (mixture, (E) and (Z) isomers)

23783-98-4 ((Z)-isomer)

297-994 ((E)-isomer)


Pesticide (acaricide, insecticide): Systemic insecticide with strong stomach action and slight contact action

Trade Names

Dimecron, D-Cron, Phosron, Pillarcron, Umecron. Discontinued names: Dixon, Apamidon, Swat


Soluble liquid (200, 500 or 1000 g/l); suspension concentrate; emulsifiable concentrate, ULV liquid; 10% granules


Basic Manufacturers

United Phosphorus (India), Bharat Pulverising Mills (India), Hindustan Ciba Geigy Ltd. (India), Hui Kwang (Taiwan)

Reasons for Inclusion in the PIC Procedure

Formulations of the substance which exceed 1000 g a.i./l are included because of their acute hazard classification and concern as to their impact on human health under conditions of use in developing countries. (Fifth meeting of the FAO/UNEP Joint Expert Group).

There are some reports of the agricultural use of phosphamidon causing health problems (see Annex 1). A few confirmed cases of human poisonings are also currently on record. (Ciba Geigy, 1994).

Registrars need to carefully consider the formulations currently used in each country when determining the risks of continued use of this pesticide. The toxicity of the active ingredient is high, but many formulations will fall into a much lower hazard category.

Hazard Classification by International Organisms

(WHO, 1996)

Technical product.: la (extremely hazardous), classification based on oral toxicity


Classification of formulations


oral toxicity

dermal toxicity

LD50: 9 mg/kg bw (see Ann. 1)

LD50: 367 mg/kg bw (see Ann. 1)


a.i. (%)

hazard class

a.i. (%)

hazard class


















Category 1 (highly toxic)


T+ (very toxic), N (dangerous to the environment), mutagene Category 3


Not evaluated by IARC

Protective measures that have been applied concerning the chemical

Measures to Reduce Exposures


WHO recommends that for the health and welfare of workers and the general population, the handling and application of phosphamidon should be entrusted only to competently supervised and well-trained applicators, who must follow adequate safety measures and use the chemical according to good application practices. Regularly exposed workers should receive appropriate monitoring and health evaluation.

In the USA, phosphamidon is a restricted use pesticide which can be used only by certified applicators.

(FAO, 1995; US-EPA, 1988; FAO/WHO)


Protective clothing as indicated in the FAO Guidelines for Personal Protection when Working with Pesticides in Tropical Climates (FAO, 1990) is required; a respirator should also be worn by mixers and when spraying tall crops. The use of flaggers should be avoided; if used, they need full protective clothing including a respirator. All equipment and protective clothing should be washed thoroughly after use; clothing should be laundered separately from family clothing.

According to US-EPA, when opening the container and when mixing, protective impermeable boots, clean overalls and gloves should be worn. Mixing, if not mechanical, should always be carried out with a paddle of appropriate length. When spraying tall crops or during aerial application, a face mask should be worn, as well as an impermeable hat, clothing, boots and gloves. All protective clothing should be washed immediately after use, including the inside of gloves (US-EPA, 1988).


The manufacture, formulation, agricultural use and disposal of phosphamidon should be carefully controlled to minimize contamination of the environment. To minimize risks for all individuals, a 48-hour interval between spraying and re-entry into any sprayed area is recommended.

According to US-EPA, unprotected persons should be kept away from tall crops for four days and away from other crops for at least 24 hours (US-EPA, 1988).

Pre-harvest intervals should be established and enforced by national authorities.

In view of the high toxicity of phosphamidon, this agent should not be considered in hand-applied ULV spraying practices.

Regulatory measures

Although the chemical has been included in the PIC procedure because it is a highly toxic pesticide that is likely to cause problems under conditions of storage, transportation and use in developing countries, some countries have reported control actions that may be of interest when considering its use as a pesticide (see below).

Control actions are reported by two countries (Belize and Japan) where the substance is banned or severely restricted for use due to its toxicity. In Indonesia, the use of phosphamidon is limited until 17 June 1997.

Not all of the reports have been determined to be of control actions which conform with the FAO/UNEP definitions of banned or severely restricted for health or environmental reasons. However, all reports are provided here since the FAO/UNEP Joint Expert Group on Prior Informed Consent decided that the substance should be included in the PIC procedure due to its potential to cause problems under conditions of use in developing countries regardless of the number of qualifying actions.

For further information on the control actions provided in Annex 2, contact the Designated National Authorities (Annex 3) in the country reporting the control action.


There are no alternatives indicated by countries reporting control actions. Alternatives have been reported in literature (Gips, 1990).

It is essential that before a country considers substituting any of the reported alternatives, it ensures that the use is relevant to its national needs. A first step may be to contact the DNA in the country where the alternative has been reported (see addresses of DNAs in Annex 3). It will then be necessary to determine the compatibility with national crop protection practices.

Packaging and Labelling

Follow FAO Revised Guidelines on Good Labelling Practice for Pesticides (FAO, 1995).

The United Nations Committee of Experts on the Transportation of Dangerous Goods (IPCS, 1993) classifies the chemical in:

Hazard Class 6.1

poisonous substance

Packing Group 2

substances and preparations presenting a serious risk of poisoning

Waste Disposal

All waste and contaminated material associated with this chemical should be considered hazardous waste. The material should be destroyed by incineration in a special, high temperature chemical incinerator facility.

See FAO Guidelines on Prevention of Accumulation of Obsolete Pesticide Stocks and The Pesticide Storage and Stock Control Manual (FAO, 1996),

It should be noted that the methods recommended in literature are often not suitable in a specific country. High temperature incinerators or secure landfills may not be available.

Exposure Limits

Type of limit



MRLs (Maximum residue limits in mg/kg) in specified products (FAO/WHO, 1996)


JMPR ADI (acceptable daily intake) in mg/kg diet (JMPR, 1986)


First Aid

Early symptoms of poisoning may include excessive sweating, headache, weakness, giddiness, nausea, vomiting, hypersalivation, stomach pains, blurred vision and slurred speech. If these symptoms occur, the person should remove contaminated clothes, wash the affected skin with soap and water and flush with large quantities of water. If in the event of collapse artificial resuscitation is used, vomit may contain toxic amounts of the substance. In case of ingestion, the stomach should be emptied as soon as possible by careful gastric lavage. Do not induce vomiting if the formulation contained hydrocarbon solvents.

Persons who have been poisoned (accidentally or otherwise) must be transported immediately to a hospital and put under the surveillance of properly trained medical staff.

Antidotes are atropine sulphate and pralidoxime chloride. General surveillance and cardiac monitoring must be maintained for at least 14 days (FAO/WHO).

Annex 1 - further information on the substance

Chemical and Physical Properties



Technical phosphamidon is a pale yellow to colourless oily liquid with a faint odour. It consists of a mixture of (Z)-isomer and (E)-isomer in the approximate proportion of 70:30.




Chemical Name

2-chloro-2-diethylcarbamoyl-1-methylvinyl dimethyl phosphate (IUPAC)

Chemical Type




Miscible with water and soluble in most organic solvents except paraffins.




Vapour Pressure

2.2 mPa 25° C



Rapidly hydrolysed by alkalis. It is corrosive to iron, tinplate and aluminium. The substance decomposes on heating or on burning, producing highly toxic fumes.

Further information in Tomlin; 121; 123; 122; 119; 154

2. Toxicity

2.1 General


Mode of action

Phosphamidon affects the nervous system by inhibiting acetylcholinesterase, an enzyme essential for normal nerve impulse transmission. An impurity of the technical product, gamma-chlorphosphamidon, inhibits mammalian cholinesterase 10 to 20 times more than pure phosphamidon (121).


Phosphamidon may be readily absorbed from the gastrointestinal tract, through the skin and by inhalation of spray mists and dusts.


In mammals, phosphamidon is metabolized mostly to polar non-toxic breakdown products.

2.2 Known Effects on Human Health


Acute Toxicity

Symptoms of poisoning

The organophosphate insecticides are cholinesterase-inhibitors. They are highly toxic by all routes of exposure. When inhaled, the first effects are usually respiratory and may include a bloody or runny nose, coughing, chest discomfort, difficult or short breath and wheezing due to constriction or excess fluid in the bronchial tubes. Skin contact with organophosphates may cause localized sweating and involuntary muscle contractions. Eye contact will cause pain, bleeding, tears, pupil constriction and blurred vision. Following exposure by any route, other systemic effects may begin within a few minutes or be delayed for up to 12 hours. These may include pallor, nausea, vomiting, diarrhoea, abdominal cramps, headache, dizziness, eye pain, blurred vision, constriction or dilation of the pupils, tears, salivation, sweating and confusion. Severe poisoning will affect the central nervous system, producing incoordination, slurred speech, loss of reflexes, weakness, fatigue, involuntary muscle contractions, twitching, tremors of the tongue or eyelids, and eventually paralysis of the body extremities and the respiratory muscles. In severe cases there may also be involuntary defecation or urination, psychosis, irregular heart beat, unconsciousness, convulsions and coma. Respiratory failure or cardiac arrest may cause death.


Short and long term exposure

A group of thirty-two people which was exposed to a phosphamidon spraying of 550 g/ha experienced conjunctival irritation and inhibition of plasmacholinesterase from 0 up to over 50% with complete recovery in 9 days.

A study with hens showed that phosphamidon did not induce delayed neurotoxicity (JMPR, 1986).


Epidemiological studies

No data available

2.3. Toxicity studies with laboratory animals and in vitro systems


Acute Toxicity


LD50 (a.i., mg/kg b.w.): 9.1-17 in different test species


LD50 (a.i., mg/kg b.w.): 367-530 in different test species


LC50 (a.i., mg/m3 air-exposure 4 hrs) 33-180


slight skin and moderate eye irritation


Short-term exposure



0.1 mg/kg bw/day


0.1 mg/kg bw/day


0.15 mg/kb bw/day

(Gunther, 1971, BBA 1996)

Daily oral doses above 1.3 mg/kg bw results in symptoms of poisoning


Long term exposure



0.05 mg/kg bw/day


0.1 mg/kg bw/day


0.1 mg/kg bw/day

(JMPR, 1986; BBA, 1996)

In a two-year study on rats with dietary concentrations from 0.2 to 80 ppm, the NOAEL was 0-05 mg/kg bw (JMPR, 1986).


Effects on reproduction

In a three-generation test of reproduction, parental generations were unaffected and there were no pathological changes in the tissues. Reproductive performance was normal. There were no significant differences in the number of new-born (Hayes, 1990).

Effects on litter size and pup viability were seen in a rat multigeneration study at maternally toxic dose levels, Phosphamidon was devoid of a teratogenic potential (JMPR, 1986).



In the mutagenicity studies, phosphamidon was negative in a number of in vitro test systems, except for one test on chromosome aberrations. Several in vivo tests on chromosome anomalies have been carried out in rodents. Reports submitted to WHO showed negative or questionable results, whereas literature data showed a positive effect (JMPR, 1986).



Carcinogenicity studies in rats were negative (JMPR, 1986).

3. Exposure



No data available.



Evaporation at 20° C is negligible; a harmful concentration of airborne particles can, however, quickly be reached when dispersed.

One case of poisoning has been reported in which the only recognized exposure was through the uprooting and cutting of shrubs that had been sprayed with phosphamidon 2 weeks before. The 50-year-old man had worked without gloves for only 1 day. In the afternoon following exposure, he suffered dizziness, repeated severe vomiting, and eventually collapsed. When brought to the hospital, he was sweating and showed excessive lacrimation. After minimum treatment, the patient regained full consciousness in a few hours, regained full strength after 2 days and recovered completely. (Hayes, 1991; IPCS, 1993)



No data available.


Accidental Poisoning

Two workers were accidentally drenched in 50% phosphamidon and six others suffered soaked feet and splashes to the arms, hands and clothing when a pipe burst. The workers immediately washed with soap and water. They suffered short-term gastric pain, headache and eye irritation; none required an antidote and all returned to work (Hayes).

4. Effects on the Environment

4.1 Fate



Phosphamidon is not persistent.



Phosphamidon does not bioconcentrate.

4.2 Ecotoxicity



LC50-96 hr (rainbow trout, Guppy, Bluegill, Channel Catfish, Carp): 3.2 - 600 mg/l (121;120)


Aquatic invertebrates

EC50 (daphnia): 0.01 - 0.022 mg/l (Ciba Geigy, 1994)



LD50-oral (5 different species): 2 - 26 mg/kg bw. The substance can be lethal by dermal exposure. Available information indicates that delayed mortality of birds occurs after application of phosphamidon (121; 120)



Phosphamidon is highly toxic to bees. LD50: 0.17 - 0.32 m g/bee. It belongs to the group of substances most toxic to bees (Delaplane, 1995).

Annex 2 - details on reported control actions




Control Action

The substance is banned for use.

Uses still allowed

No remaining uses are allowed.


Highly toxic.




Control Action

Decree of the Minister of Agriculture N.473/Kpts/TP.270/6/96, dated 17 June 1996: the discontinuance of the registration of phosphamidon was stipulated. The owner of phosphamidon has been given a time period of one year for using up the stocks after the date of the decree.

Uses still allowed





Control Action

Severe Restrictions; uses other than those specified by Cabinet Order are prohibited; no use has been designated.

Uses still allowed

Scientific research by authorized researcher.


Very strong toxicity.

Annex 3 - list of designated national authorities




Sanitation Engineer


Ministry of Health Public Health Bureau


Belize City




501-92-2640 /

The Secretary


Pesticides Control Board Department of Agriculture, Mr Mario



Central Farm Cayo


102 Foreign Bz






62 (21) 7805652 /7806213

Direktorat Bina Perlindungan Tanaman Pesticide Committee


62 (21)

Jln. AUP. Pasar Minggu


12520 Jakarta




021 583918

Bapedal Offices , Ms. Masnellyarti Hilman


021 5703365

Arthaloka Building, 11th Floor, Jl. Jend Sudirman No. 2


6221 583918

Jakarta Pusat





81 335013964

The Director


81 335916640

Ministry of Agriculture, Forestry and Fisheries Plant Protection


Kasumigaseki 1-2-1 Chiyoda-ku


100 Tokyo



81 335803311

The Director


81 3 35920364

Ministry of Foreign Affairs Global Issues Division, Multilateral Cooperation Dept., Mr. Toshiki Kanamori


2-2-1 Kasumigaseki, Chiyoda-ku


100 Tokyo


Industrial and consumer product chemicals




Pesticides, industrial and consumer product chemicals

Annex 4 - references

The information on phosphamidon given in this DGD is mainly based on documents published by WHO, FAO and the International Programme on Chemical Safety (IPCS). If important information from other sources has been used, these references are noted in the text. The following list also includes other publications containing useful information.

Asian Development Bank, 1987. Handbook on the use of pesticides in the Asia-Pacific region. ADB, Manila. Biologische Bundesanstalt für Land- und Forstwirtschaft, 1996. Communication to FAO.

Bundesministerium für Arbeit, 1995. TRGS 905 Technische Regel für Gefahrstoffe. BArBI. Nr. 4/1995 S.70, Nr. 6/1995 S.50, Nr. 10/1995 S.46.

Ciba-Geigy Ltd., 1994. Phosphamidon, Toxicological Evaluation Plant Protection Safety Evaluation

Codex Alimentarius Commission 1996. Codex Alimentarius. Food and Agriculture Organization/World Health Organization Joint FAO/WHO Food Standards Programme. Volume 2B Second Edition, revised 1996.

Delaplane, Keith S., 1995. Commonly used Pesticides Grouped According To Their Relative Hazards To Honey Bees,

FAO, 1996. Pesticide storage and stock control manual. Food and Agriculture Organization, Rome.

FAO, 1996. Technical guidelines on disposal of bulk quantities of obsolete pesticides in developing countries. Food and Agriculture Organization, Rome.

FAO, 1990. Guidelines for personal protection when working with pesticides in tropical countries. Food and Agriculture Organization, Rome.

FAO, 1995. Revised guidelines on good labelling practices for pesticides. Food and Agriculture Organization, Rome.

FAO/WHO, Data Sheet on Pesticides No. 74: Phosphamidon. FAO/WHO/VBC/DS87.74 IPCS Inchem CD-ROM.

FAO/WHO, 1986. Pesticide Residues in Food -1986; Report Joint Meeting on Pesticide Residues (JMPR); FAO, Rome; Plant Production and Protection Paper 77.

FAO/WHO, 1986. Pesticide Residues in Food -1986; Evaluations, Part II - Toxicology. Joint Meeting on Pesticide Residues (JMPR); FAO, Rome; Plant Production and Protection Paper 78/2.

Farm Chemicals Handbook 1994. Meister Publishing, Willoughby, Ohio, USA.

Gunther, F.A.; Gunther, J.D. 1971. Phosphamidon Residue Reviews, Volume 37, Springer Verlag Berlin, Heidelberg, New York

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

Hayes, W.J. and E.R. Laws (ed.), 1991. Handbook of Pesticide Toxicology. Academic Press, lnc.,New York. IPCS, 1993. ICSC: Phosphamidon. IPCS/CEC InChem CD ROM.

IPCS, 1993. Health and Safety Guide No. 79: Methamidophos. International Programme on Chemical Safety, IPCS/ World Health Organization, Geneva.

NCSR, 1995. ARS Pesticide Properties,

NTP, 1991. NTP Chemical Repository Phosphamidon, http://ntp-db.niehs.nih...m1/Radian13171-21-6.txt.

Pesticide Trust, 1989. The FAO Code: missing ingredients. Pesticides Trust, London N1 2UN, United Kingdom

Stillmeadow Inc, 1988. 21-day dermal toxicity study in rabbits EPA Guidelines No. 82-2. Agricultural Division of Ciba-Geigy Corporation.

Tomlin, Clive 1994. The Pesticide Manual: A World Compendium. (10th ed.), British Crop Protection Council, Surrey, (United Kingdom)

US-EPA, 1988. Pesticide Fact Sheet No. 154: Phosphamidon. US Environmental Protection Agency. USEPA, Washington, DC, USA.

WHO, 1996. Recommended classification of pesticides by hazard and guidelines to classification 1996-1997. WHO/PCS/96.3. World Health Organization, IPCS, Geneva.


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