WORLD HEALTH ORGANIZATION FOOD AND AGRICULTURE
ORGANIZATION
ORGANISATION MONDIALE DE LA SANTE ORGANISATION POUR L'ALIMENTATION
ET L'AGRICULTURE
VBC/DS/78.31
ORIGINAL: ENGLISH
DATA SHEETS ON PESTICIDES No. 31
PHOXIM
It must be noted that the issue of a Data Sheet for a
particular pesticide does not imply endorsement of the pesticide by
WHO or FAO for any particular use, or exclude its use for other
purposes not stated. While the information provided is believed to
be accurate according to data available at the time when the sheet
was compiled, neither WHO nor FAO are responsible for any errors or
omissions, or any consequences therefrom.
The issue of this document does Ce document ne constitue pas une
not constitute formal publication. Il ne doit faire
publication. It should not be l'objet d'aucun compte rendu ou
reviewed, abstracted or quoted résumé ni d'aucune citation sans
without the agreement of the l'autorisation de l'Organisation
Food and Agriculture des Nations Unies pour
Organization of the United l'Alimentation et l'Agriculture
Nations or of the World Health ou de l'Organisation Mondiale de
Organization. la Santé.
CLASSIFICATION:
Primary Use: Insecticide
Chemical Group: Organophosphorus compound
Date Sheet No: 31
Date Issued:
1. GENERAL INFORMATION
1.1 COMMON NAME:
Phoxim
1.1.1 Identity
Alpha-[[(diethyoxyphosphinothioyl)-ox]-imino]benzeneacetonitrile
1.1.2 Synonyms:
SRA 7502
Bayer 77488
Baythion
Volaton (formerly Valexon)
OMS-1170
Local synonyms:
1.2 SYNOPSIS
An organophosphorus insecticide of low acute oral and dermal
toxicity to mammals but with a pronounced selectivity in toxicity to
insects, particularly those in stored products and those affecting
man.
1.3 SELECTED PROPERTIES
1.3.1. Physical characteristics
When pure, a yellow to yellow-brown liquid, melting point 5-6°C,
boiling point 102°C at 0.01 mm Hg. The technical material is a
red-brown liquid. Density d 20 1.17 technical.
4
1.3.2 Solubility
Water at 20°C, 7 ppm; readily soluble in alcohol, ketones,
acetonitrile, hydrocarbons and to a lesser extent in vegetable and
mineral oils.
1.3.3 Stability
Decomposes below boiling point at normal pressure. Badly stored
formulations could develop a smell of cyanide. Stable in water and
acids. Hydrolyses in alkaline solution.
1.1.4 Vapour pressure (volatility)
About 10-4 mm Hg for pure a.i. at 27°C.
1.4 AGRICULTURE, HORTICULTURE AND FORESTRY
1.4.1 Common formulations
500 g/l emulsifiable concentrate, 40% wettable powder, 5% granules,
10 granules and 800 g/l concentrate for ULV application.
1.4.2 Pests mainly controlled
Very effective against coleoptera and lepidoptera; and against
wireworms, rootworms and dipterous larvae in soil.
1.4.3 Use pattern
Used for the control of insects liable to infest stored grain, peas,
beans, rice, tobacco, dried fruit and skins. Application is as a
spray up to 0.1% a.i. concentration, at up to 20 litres per 100 m2
in empty stores, granaries and ships. May also be applied to empty
jute sacks. Granular formulations are preferred for soil
applications. It is of brief persistence and is non-systemic. It is
very effective against locusts at 0.3-0.5 kg a.i./ha.
1.4.4 Unintended effects
Not intended for direct application to food or feeding stuffs. Toxic
to fish and to some beneficial insects (see paragraphs 2.3.1 and
2.3.3).
1.5 PUBLIC HEALTH PROGRAMMES:
A useful larvicide recommended for use in outdoor surface water.
1.6 HOUSEHOLD USE:
Not recommended for household use.
2. TOXICOLOGY AND RISKS
2.1 TOXICOLOGY - MAMMALS
2.1.1 Absorption route
Absorbed from the gastrointestinal tract and more slowly through
intact skin.
2.1.2 Mode of action
Cholinesterase inhibition after conversion to the oxygen analogue
(P=O phoxim). This is rapidly hydrolysed in mammals to diethyl
phosphoric acid. Variations in the rate of hydrolysis probably
account for species variation.
2.1.3 Excretion
In mice 80% of an oral dose of 10.5 mg/kg is excreted in the urine
in 80 hours. Excretion of higher doses is slower. Metabolites
include phoxim carboxylic acid and 0,0 diethyl phosporothioc acid.
2.1.4 Toxicity, single dose
Oral: LD50 rat (M) 2170 mg/kg
(F) 1976 mg/kg
mouse (M) 1935 mg/kg
(F) 2340 mg/kg
Dermal: LD50 rat (M) > 1000 mg/kg (maximum tested)
Most susceptible species: cat )
dog ) (F) Oral LD50 250-500 mg/kg
guinea-pig (F) oral LD50 600 mg/kg
2.1.5 Toxicity, repeated doses
Oral: Rats tolerated doses of 100 mg/kg daily for ten weeks
without toxic symptoms, although there was moderate inhibition of
cholinesterase.
Inhalation: LD50 determined in a 4-hour test with statio
treatments at 30 minute intervals was > 1.66 mg/m3 for rats and
mice and between 1.16 and 1.66 mg/m3 for rabbits. The LC50 for
rats exposed to a dynamic spray for four hours exceeded
2500 mg/m3.
Dermal: No information.
Cumulation of compound: Phoxim is not cumulative.
Cumulation of effect: Repeated high exposure may produce
cumulative inhibitory effect on cholinesterase.
2.1.6 Dietary studies
Short-term: Rats of both sexes were given repeated oral doses of
5, 15, 50, 150 and 500 mg/kg in the diet for three months. There
were no deaths at any dose. Symptoms of cholinesterase depression
were observed in the 500 mg/kg dose group. Food consumption and
growth were not affected up to 150 mg/kg but the 500 mg/kg dose
group had significantly lower body weights. The no-effect level was
5 mg/kg. Rats were fed at 1, 2, 4, 6 and 10 mg/kg phoxim in the diet
for up to five months. No adverse effects were noted. Calves were
fed at dosage levels up to 2.6 mg/kg in diet for three months. The
general state of animals remained normal but at the highest dose
level, serum cholinesterase was inhibited after two months and
erythrocyte cholinesterase reached a minimum after three months.
Long-term: No information.
2.1.7 Supplementary studies of toxicity
Carcinogenicity: No information.
Teratogenicity: No information.
Neurotoxicity: Chickens were treated orally up to 50 mg/kg and
intraperitoneally up to 37.5 mg/kg, no neurotoxic symptoms observed.
2.1.8 Modification of toxicity
No information.
2.2 TOXICOLOGY - MAN
2.2.1 Absorption
Ingestion may be a significant route of absorption in man. However,
dermal absorption from high concentration emulsifiable concentrates
and particularly the 80% ULV concentrate could be important.
2.2.2 Dangerous doses
Single - Not known.
Repeated - Not known.
2.2.3 Observations on occupationally exposed workers
A village-scale trial, wearing protective clothing, was carried out
in Northern Nigeria in 1971. Workers handling the insecticide
complained of weakness after work but no clinical symptoms were
recorded. Two out of four spraymen complained of face pains lasting
for one hour after work, but no other complaints or clinical effects
were observed in spraymen or villagers exposed to phoxim. Very
slight depression of whole-blood cholinesterase was dejected in some
spraymen and some villagers.
2.2.4 Observations on exposure of the general population
No information.
2.2.5 Observations of volunteers
No information.
2.2.6 Reported mishaps
No information. Poisoning in humans by phoxim has not been reported.
2.3 TOXICITY TO NON-MAMMALIAN SPECIES
The entries in these sections are intended to draw attention to
special risks and to give warnings of any need for special
protection.
2.3.1 Fish
Toxic to fish. The LC50 (48-hour exposure) is: for rainbow trout
< 1.0 mg/l, for goldfish 10-100 mg/l, for carp 1-10 mg/l and for
mosquito fish LC100 5 mg/l.
2.3.2 Birds
Doves (Columbia livia) can tolerate at least 50 mg/kg. At
100 mg/kg part of the dose was vomited. LD50 hens 37.5 mg/kg.
2.3.3 Other species
Toxic to bees by contact and vapour action. Contact LD50
0.8 µg/insect.
3. FOR REGULATORY AUTHORITIES - RECOMMENDATIONS ON REGULATION OF
COMPOUND
3.1 RECOMMENDED RESTRICTIONS ON AVAILABILITY
(For definition of categories, see introduction)
80% concentrate for ULV application Category 3. Other liquid
formulations over 25% and solid formulations over 40% Category 4.
All other formulations of lower concentration Category"
3.2 TRANSPORTATION AND STORAGE
All formulations - Should be transported or stored in clearly
labelled leakproof containers out of reach of children, away from
food or drink.
3.3 HANDLING
Formulations in Categories 3 and 4 - Adequate washing facilities
should be provided at all times during handling and should be close
to the site of the handling. Eating, drinking and smoking should be
prohibited during handling and before washing after handling.
Formulations in Category 5 - No facilities other than those needed
for the handling of any other chemical may be required.
3.4 DISPOSAL AND/OR DECONTAMINATION OF CONTAINER
All formulations - Containers may be decontaminated (for method
see paragraph 4.3 in Part 4). Decontaminated containers should not
be used for food and drink. Containers that are not decontaminated
should be burned or should be crushed and buried below topsoil. Care
must be taken to avoid subsequent contamination of water sources.
3.5 SELECTION, TRAINING AND MEDICAL SUPERVISION OF WORKERS
Formulations in Categories 3 and 4 - Pre-employment medical
examination and periodic cholinesterase test for workers desirable.
Warning of workers to avoid contact essential.
3.6 ADDITIONAL REGULATIONS RECOMMENDED IF DISTRIBUTED BY AIRCRAFT
No special regulation recommended.
3.7 LABELLING
Formulations in Categories 3 and 4 - Minimum cautionary statement:
"Phoxim is an organophosphorus compound which inhibits
cholinesterase. It is of moderate toxicity bat may be poisonous if
swallowed. Keep the material out of reach of children and well away
from foodstuffs, animal feed and their containers. If poisoning
occurs call a physician. Atropine and pralidoxime are specific
antidotes and artificial respiration may be needed".
Formulations in Category 5 - Minimum cautionary statement
This formulation contains phoxim. Keep the material out of reach of
children and well away from foodstuffs, animal feed and their
containers.
3.8 RESIDUES IN FOOD
Maximum residue levels have not yet been recommended by the FAO/WHO
Meeting on Pesticide Residues.
4. PREVENTION OF POISONING IN MAN AND EMERGENCY AID
4.1 PRECAUTIONS IN USE
4.1.1 General
Phoxim is an organophosphorus insecticide of moderate to low
mammalian toxicity. It can be absorbed by ingestion, by inhalation
of dust and to some extent through intact skin. Although dermal
absorption from diluted spray is of little significance, absorption
from high concentration liquid formulations (especially the 80% ULV
concentrate) may be important. In dilute liquid formulations the
vehicle (solvent) may be more toxic than the insecticide.
4.1.2 Manufacture and formulations
Although volatility is low, vapour and dust should be controlled.
Protective equipment for skin and respiratory protection is
desirable.
4.1.3 Mixers and applicators
When opening the container and when mixing, care should be taken to
avoid contact with the mouth and eyes. If necessary a facial visor
and gloves should be worn. Mixing, if not mechanical, should always
be carried out with a paddle of appropriate length, Splashes should
be washed immediately from the skin or eyes with large quantities of
water. Before eating, drinking or smoking, hands and other exposed
skin should be washed.
4.1.4 Other associated workers (including flagmen in aerial
operations)
Persons exposed to phoxim and associated with its application should
observe the precautions described above in 4.1.3 under "Mixers and
applicators".
4.1.5 Other populations likely to be affected
Populations will not be exposed to hazardous amounts of phoxim
during good agricultural practice.
4.2 ENTRY OF PERSONS INTO TREATED AREAS
Phoxim degrades rapidly under field conditions and persons may enter
treated areas as soon as the spray has dried without being exposed
to hazardous amounts of phoxim.
4.3 DECONTAMINATION OF SPILLAGE AND CONTAINERS
Residues in containers should be emptied in a diluted form into a
deep pit taking care to avoid ground waters. The empty container may
be decontaminated by rinsing two or three times with water and
scrubbing the sides. An additional rinse should be carried out with
5% sodium hydroxide solution which should remain in the container
overnight. Impermeable gauntlets should be worn during this work and
a soakage pit should be provided for the rinsings. Decontaminated
containers should not be used for food and drink. Spillage of phoxim
and its formulations should be removed by washing with 5% sodium
hydroxide solution and then rinsing with large quantities of water.
4.4 EMERGENCY AID
4.4.1 Early symptoms of poisoning
Early symptoms of poisoning following the ingestion of phoxim may
include excessive sweating, headache, weakness, giddiness, nausea,
vomiting, stomach pains, blurred vision, slurred speech, and muscle
twitching. If a massive dose has been swallowed there may be
convulsion, coma, loss of reflexes and loss of sphincter control.
Symptoms of poisoning are very unlikely to occur following dermal
contact.
4.4.2 Treatment before person is seen by a physician, if these
symptoms appear exposure
If swallowed, vomiting should be induced if the person is conscious.
the event of collapse, artificial respiration should be given.
5. FOR MEDICAL AND LABORATORY PERSONNEL
5.1 MEDICAL DIAGNOSIS AND TREATMENT IN CASES OF POISONING
5.1.1 General information
An organophosphorus insecticide of moderate to low mammalian
toxicity which can be absorbed by ingestion, by inhalation and to
some extent through intact skin. Although dermal absorption from
diluted spray may not be significant absorption from high
concentration liquid formulations may be important. In dilute
formulations the vehicle (solvent) may be more toxic than the
insecticide. Phoxim itself is a weak inhibitor of acetyl
cholinesterase but is metabolized to a more active inhibitor which
is then quickly inactivated; the metabolites are excreted in the
urine. Poisoning in man has not yet been reported.
5.1.2 Symptoms and signs
Based upon studies and upon symptoms of poisoning from other
organophosphorus pesticides, initial symptoms of poisoning may
include excessive sweating, headache, weakness, giddiness, nausea,
vomiting, stomach pains, blurred vision, slurred speech and muscle
twitching. In the event of ingestion of an excessive dose more
advanced symptoms of poisoning may be convulsions, coma, loss of
reflexes and loss of sphincter control.
5.1.3 Laboratory
The most important finding is reduction in activity of blood
cholinesterases.
5.1.4 Treatment
If pesticide has been ingested, unless the patient is vomiting,
rapid gastric lavage should be performed using 5% sodium
bicarbonate, if available. In spite of the low dermal toxicity after
skin contact, it is advisable to wash the skin with soap and water.
If the compound has entered the eyes, they should be washed with a
lot of water. Persons without signs of respiratory inefficiency out
with manifest peripheral symptoms should be treated with 2-4 mg of
atropine sulfate and 1000-2000 mg of pralidoxime chloride or 250 mg
of zoxogonin (adult dose) by slow intravenous injection. More
atropine may be given as needed. Persons with severe intoxication
with respiratory, difficulties, convulsions and unconsciousness
should immediately be given atropine and a reactivator. In such
severe cases 4-6 mg of atropine sulfate should be given initially
followed by repeated doses of 2 mg at 5-10 minute intervals. The
patient's condition including respiration, blood pressure, pulse
frequency, salivation and convulsions should be carefully observed
as a guide to further administration of atropine. If the patient is
cyanotic, artificial respiration should be given at the same time as
atropine sulfate. The airways should be kept free and artificial
respiration if required, should be preferably by mechanical means.
If necessary intubation should be performed.
Contraindicated are morphine, barbiturates, phenothiazine
tranquillizers and central stimulants of all kinds.
5.1.5 Prognosis
As there have been no reports of poisoning of man with phoxim the
prognosis is not known. By analogy with other moderately toxic
organophosphorus compounds it may be assumed that if the acute toxic
effect is survived the chances of complete recovery are good. In
very severe cases following the ingestion of a massive dose of
phoxim it is possible that without adequate artificial respiration
prolonged hypoxia could give rise to permanent brain damage.
5.1.6 References of previously reported cases
None.
5.2 SURVEILLANCE TESTS
Normal Action Symptomatic
Test level level level
Plasma cholinesterase 100%1 50% variable
Erythrocyte cholinesterase 100% 70% usually < 40%
5.3 LABORATORY METHODS
References are given only.
5.3.1 Detection and assay of compound
Particulars of a GLC method for analysis of residues in plants using
a thermionic phosphorus detector are available from Bayer,
Leverkusen. [Drager, G. (1969) Pflantzenschutz Nachrichten 22,
No. 3, 301]
1Percentage of pre-exposure activity by any test.
5.3.2 Other tests in cases of poisoning
Levels of cholinesterase in blood provide the most useful diagnosis
of poisoning. See: Michel, N. O. (1949) J. Lab. Clin. Med., 34,
1564-1568: Ellman, G. L., Courtney, K. D., Andreas, V. Jr. &
Featherstone, R. M. (1961) Biochem., Pharmacol., 7, 88-95.
* * *