WORLD HEALTH ORGANIZATION FOOD AND AGRICULTURE
ORGANIZATION
ORGANISATION MONDIALE DE LA SANTE ORGANISATION POUR L'ALIMENTATION
ET L'AGRICULTURE
VBC/DS/78.32
ORIGINAL: ENGLISH
DATA SHEETS ON PESTICIDES No. 32
CHLORPHOXIM
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
Secondary Use:
Chemical Group: Organophosphorus compound
Date Issued:
1. GENERAL INFORMATION
1.1 COMMON NAME
Chlorphoxim
1.1.1 Identity:
2-chloro-alpha
-[[(diethoxyphosphinothioyl)ox]imino]benzeneacetonitrile
1.1.2 Synonyms:
Baythion C
BAY 78,182
SRA 7747
OMS 1197
Local synonyms:
1.2 SYNOPSIS
Chlorphoxim is an organophosphorus insecticide of low acute oral and
dermal toxicity effective against many pests.
1.3 SELECTED PROPERTIES
1.3.1 Physical characteristics
When pure white crystalline solid melting point 66.5°C.
1.3.2 Solubility
Almost insoluble in water, 2 ppm. Readily soluble in cyclohexanone,
toluene and methylene chloride and to a lesser extent in
isopropanol.
1.3.3 Stability
Decomposes below boiling point at normal pressure. Badly stored
formulations could develop a smell of cyanide. Hydrolysed in
alkaline solution.
1.3.4 Vapour pressure (volatility)
No information.
1.4 AGRICULTURE, HORTICULTURE AND FORESTRY
Chlorphoxim has not yet been developed for use in agriculture,
horticulture or forestry.
1.5 PUBLIC HEALTH PROGRAMMES:
Chlorphoxim is effective against many public health pests such as
Aedes spp., Anopheles spp., Culex spp., and Simulium spp.
Two formulations are available, 200 g/l emulsifiable concentrate for
spraying (including ULV application) and a 50% wettable powder.
Recommended rates are 500-1500 ml of ULV concentrate Der hectare and
the 50% wettable powder as a surface deposit at 4 g formulation/m2
(2 g/m2 active ingredient).
1.6 HOUSEHOLD USE:
Not recommended for household use.
2. TOXICOLOGY AND RISKS
2.1 TOXICOLOGY - MAMMALS
2.1.1 Absorption route
Absorbed from gastrointestinal tract and more slowly through intact
skin.
2.1.2 Mode of action
Cholinesterase inhibition after conversion to the oxygen analogue
(P = 0 chlorphoxim).
2.1.3 Excretion
No information.
2.1.4 Toxicity, single dose
Oral: LD50 Rat (M,F) > 2500 mg/kg
Mouse (M) > 1500 mg/kg )
(F) > 10 000 mg/kg )
Guinea pig > 1000 mg/kg )
Cat > 1000 mg/kg ) maximum tested
Dog > 1000 mg/kg )
Rabbit > 1000 mg/kg )
)
Dermal: LD50 Rat > 500 mg/kg )
Most susceptible species - No information
2.1.5 Toxicity, repeated doses
Inhalation: LC50 rat determined in a dynamic inhalation
apparatus, with 4-hour exposure, active ingredient in alcohol +
Lutrol (1:1): > 300 mg/m3; 20% concentrate > 1303 mg
formulation/m3.
Cumulation of compound: Chlorphoxim is not cumulative.
Cumulation of effect: Repeated high exposure may produce a
cumulative inhibitory effect on cholinesterase.
2.1.6 Dietary studies
Short-term: Rats of both sexes were fed oral doses of 0, 5, 15, 50
and 150 mg/kg in the diet for three months. There was no inhibition
of cholinesterase at the 50 mg/kg dose level but 150 mg/kg dose
inhibited cholinesterase activity in plasma and erythrocytes. There
was an insignificant increase in kidney weight of females at
150 mg/kg.
Four male and four female Beagle dogs were fed 0, 1, 10, and
100 mg/kg in the diet for three months. Plasma cholinesterase was
depressed in the 10 mg/kg dose group but significant depression of
erythrocyte cholinesterase was observed only in the 100 mg/kg dose
group. The no-effect level was 1 mg/kg.
2.1.7 Supplementary studies of toxicity
Carcinogenicity: No information.
Teratogenicity: Rats, 6-15 days pregnant, were given doses of 40,
80 or 150 mg/kg of chlorphoxim. No embryotoxicity or teratogenicity
was observed.
Neurotoxicity: Hens were treated orally and intraperitoneally. No
neurotoxic symptoms observed.
Mutagenicity: In a dominant lethal test on male mice using a dose
of 500 mg/kg there was no indication of mutagenic activity.
2.1.8 Modifications of toxicity
No information.
2.2 TOXICOLOGY - MAN
2.2.1 Absorption
Ingestion is likely to be the significant route of absorption in
man. However, dermal absorption from Liquid concentrates 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 was carried out in 1972. No complaints were
received and no adverse effects could be detected among exposed
baggers, spraymen or inhabitants. There was no depression of
whole-blood cholinesterase in spraymen or exposed residents.
2.2.4 Observations on exposure of the general population
No information.
2.2.5 Observations on volunteers
No information.
2.2.6 Reported mishaps
No information. Poisoning in humans by chlorphoxim has not been
reported.
2.3 TOXICITY TO NON-MAMMALIAN SPECIES
2.3.1 Fish
Toxic to fish.
The LC50 (96-hour exposure)
for goldfish 100-150 mg/l
carp 100-150 mg/l
golden orfe ca 10 mg/l
mosquito fish ca 6 mg/l
red feather ca 0.5 mg/l
(Scardinius
erythrophthalmus)
2.3.2 Birds
Oral LD50 Japanese quail 50-100 mg/kg
Canary about 200 mg/kg
2.3.3 Other species
No information.
3. FOR REGULATORY AUTHORITIES - RECOMMENDATIONS ON REGULATIONS
OF COMPOUND
3.1 RECOMMENDED RESTRICTIONS ON AVAILABILITY
(for definition of categories, see introduction).
Liquid formulations 20% and over and solid formulations over 40%,
Category 4.
All other formulations, Category 5.
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 Category 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.
Formulation in Category 5 - No facilities other than those
required for the handling of any chemical.
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 Category 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 Category 4 - Minimum cautionary statement:
"Chlorphoxim is an organophosphorus compound which inhibits
cholinesterase. It is of low toxicity but 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".
3.8 RESIDUES IN FOOD
Chlorphoxim has not yet been considered by the Joint FAO/WHO Meeting
on Pesticide Residues.
4. PREVENTION OF POISONING IN MAN AND EMERGENCY AID
4.1 PRECAUTIONS IN USE
4.1.1 General
Chlorphoxim is an organophosphorus insecticide of 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 liquid
formulations such as the 20% ULV concentrate may be important. In
dilute liquid formulations the vehicle (solvent) may be more toxic
than the insecticide.
4.1.2 Manufacture and formulation
Although volatility is low, vapour and dust should be controlled.
Protective equipment for skin and respiratory protection may be
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 of 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 chlorphoxim 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 are not likely to be exposed to hazardous amounts of
phoxim during properly conducted public health spraying.
4.2 ENTRY OF PERSONS INTO TREATED AREAS
Persons may enter treated areas as soon as the spray has dried
without being exposed to hazardous amounts of chlorphoxim.
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 rinsing. Decontaminated
containers should not be used for food and drink. Spillage of
chlorphoxim 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 chlorphoxim
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.
4.4.2 Treatment before person is seen by a physician, if these
symptoms appear following exposure
If swallowed, vomiting should be induced if the person is conscious.
In the event of collapse, artificial respiration should be given.
5. FOR MEDICAL AND LABORATORY PERSONNEL
5.1 MEDICAL DIAGNOSIS AND TREATMENT OF CASES OF POISONING
5.1.1 General information
An organophosphorus insecticide of 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. Chlorphoxim itself
is a weak inhibitor of acetyl cholinesterase but is metabolized to a
more active inhibitor which is then quickly inactivated and the
metabolites 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
severe 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
cholinesterase.
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
plenty of water. Persons without signs of respiratory inefficiency
but with manifest peripheral symptoms should be treated with 2-4 mg
of atropine sulfate and 100-2000 mg of pralidoxime chloride or
250 mg of toxogonin (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
necessary should be applied, 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 chlorphoxim
the prognosis is not known. By analogy with 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
chlorphoxim 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
Test Normal level Action level Symptomatic level
Plasma cholinesterase 100%1 50% variable
Erythrocyte cholinesterase 100% 70% usually < 40%
1Percentage of pre-exposure activity by any test.
5.3 LABORATORY METHODS
References are given only.
5.3.1 Detection and assay of compound
A GLC method for analysis of residues of phoxim in plants using a
thermionic phosphorus detector is likely to be applicable to the
analysis of chlorphoxim and is available from Bayer, Leverkusen.
[Dräger, G. (1969) Pflantzenschutz Nachrichten 22, No. 3, 301]
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.
* * *