WORLD HEALTH ORGANIZATION FOOD AND AGRICULTURE
ORGANIZATION
ORGANISATION MONDIALE DE LA SANTE ORGANISATION POUR L'ALIMENTATION
ET L'AGRICULTURE
WHO/VBC/DS/88.67
ORIGINAL: ENGLISH
Distr.: LIMITED
DATA SHEETS ON PESTICIDES No. 67
1988
THIOMETON
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, acaricide
Secondary use: None
Chemical group: Organophosphorus compound
Date issued: March 1988
1.0 GENERAL INFORMATION
1.1 COMMON NAME
thiometon (BSI, E-ISO, F-ISO, F-ISO, JMAF), dithiomethon
(France), M-81 (USSR), exceptions (Federal Republic of Germany,
Portugal, Turkey).
1.1.1 Identity
IUPAC: S-2-ethylthioethyl O,O-dimethyl phosphorodithioate
CAS: S-[2-(ethylthio)ethyl] O,O-dimethyl phosphorodithioate
CAS Reg. No.: 640-15-3
Molecular formula: C6H15O2PS3
Relative molecular mass: 246.3
Structural formula:
1.1.2 Synonyms
Dithiometon, EkatinR, Ekatin Aerosol, EkatinR, ULV, Ekatin
WF ULV, Intrathion, Intration, Luxtstelm, M-81.
1.2 SYNOPSIS
Thiometon is a systemic organophosphorus insecticide -
acaricide with residual activity of up to three weeks. It is highly
toxic to mammals by the oral route. Thiometon is rapidly metabolized
in both animals and plants to the water-soluble sulfoxide and
sulfone. Some of the metabolites of thiometon are more potent
inhibitors of cholinesterases and are more toxic than thiometon
itself.
1.3 SELECTED PROPERTIES
1.3.1 Physical characteristics
The pure product is a colourless oil with a characteristic
odour; b.p. 110°C at 13.3 Pa, d20 1.209, n20 1.5515.
4 4
1.3.2 Solubility
Titometon is soluble in water at 200 mg/L (25°C), and in most
organic solvents, but only slightly soluble in light petroleum.
1.3.3 Stability
Low stability in the pure state, but stable in non-polar
solvents. It is hydrolysed in aqueous solutions, both under alkaline
or acid conditions.
1.3.4 Vapour pressure: 23 mPa at 20°C.
1.4 AGRICULTURE, HORTICULTURE AND FORESTRY
1.4.1 Common formulations
Emulsifiable concentrates (250 g/L) and ULV (150 g/L). In
emulsifiable concentrate formulations it is mixed with parathion,
endosulfan, fenvalerate or quinalphos, and in ULV concentrate with
parathion.
1.4.2 Susceptible pests
Thiometon is effective against sucking insects, mainly aphids,
and mites on most crops. Others include psyllids, sawflies, jassids
and thrips.
1.4.3 Use pattern
Used as a foliar spray on many crops and ornamentals. Applied
at a 0.1% concentration rate when the plant is actively growing for
maximum systemic effect. May also be used as a soil drench.
1.4.4 Unintended effects
Considered non-phytotoxic and of low toxicity to bees.
1.5 PUBLIC HEALTH PROGRAMMES
No recommended usage.
1.6 HOUSEHOLD USE
No recommended usage.
2.0 TOXICOLOGY AND RISKS
2.1 TOXICOLOGY - MAMMALS
2.1.1 Absorption route
Thiometon may be absorbed from the gastro-intestinal tract,
through the intact skin or by inhalation of spray mist.
2.1.2 Mode of action
Thiometon is an organophosphorus insecticide which is not a
strong cholinesterase inhibitor but when metabolized it converts to
several potent cholinesterase inhibitors. Absorption is rapid and
formulations may be more toxic than the pure compound.
2.1.3 Excretion products
Rats given 15 mg/kg b.w. of labelled thiometon orally, after 24
hours excreted 83% of the radioactivity in the urine and 5.5% in the
faeces, with 4% remaining in the carcass after 96 hours. Maximum
blood levels were attained after three hours. Primary metabolites
were O-thiometon sulfoxide, O-thiometon sulfone and O,O-
dimethylphosphoric acid in proportions of 26, 5 and 52% of the
urinary excretion, respectively.
2.1.4 Toxicity, single dose
Oral LD50:
Rat 225 mg/kg b.w. (pure)
Rat 190 mg/kg b.w. (technical thiometon)
Rat 100-120 mg/kg b.w. (as 25% EC formulation)
Guinea pig (M) 261 mg/kg b.w.
Rabbit (M) 95 mg/kg b.w.
Mouse (M) 66 mg/kg b.w.
Mouse (F) 62 mg/kg b.w.
Dermal LD50 (four hour exposure):
Rat (M) >1 100 mg/kg b.w.
Intraperitoneal LD50:
Rat (M) 45 mg/kg b.w.
Rat (F) 47 mg/kg b.w.
Intravenous LD50:
Rat (M) 27.5 mg/kg b.w.
Rat (M) 35.5 mg/kg b.w.
Rabbit 22.0 mg/kg b.w.
Inhalation LC50 (one hour):
Rat (M,F) >60 mg/L
Irritation:
Application of 0.5 ml 94.8% pure thiometon for 24 hours with
occlusion to intact or abraded rabbit skin showed no evidence of
irritative effects. Instillation of 0.1 ml 94.8% pure thiometon to
rabbit eyes showed that thiometon had no irritant or corrosive
effect.
2.1.5 Toxicity, repeated doses
Results of studies in rats given repeated doses of thiometon
were inconsistent. Formulations may be significantly more toxic than
the pure compound.
Oral: In a 12 month study in rats given thiometon from 0 to
18 mg/kg/day by gastric intubation, a level of > 1 mg/kg/day
caused a decrease in erythrocyte cholinesterase activity. At > 2
mg/kg/day an additional decrease in plasma acholinesterase activity
occurred. A slight reduction in weight gain occurred at 6 mg/kg/day
which became more significant at the highest dose level. This effect
was seen only in male rats. All histological findings were normal.
In another experiment rats given 4 to 7 doses of Intrathion
(thiometon, supposedly impure) intragastrically at a dose level of
0.6 LD50 at three day intervals, showed clinical signs of
poisoning after each dose. Some rats showed flaccid neuro-muscular
paralysis after 10 to 19 days and on sacrifice showed significant
decreases in the total phospholipid, sphingomyeline, phosphatidyl
ethanolamine, phosphatidylserine and total and free cholesterol
levels in lipid extracts of the spinal cords. Also seen were
significant increases in phosphoinositides, polyglycerophosphatides,
lecithin and esterified cholesterol levels.
In a 13 week study, male rats were given 5, 10, 15 or 20
mg/kg/day. All animals showed a mild to severe poisoning with all
animals in dose groups >15 mg/kg/day dying. The survivors
recovered after 10 weeks whilst still receiving thiometon and
histological examination failed to reveal abnormal pathology at 13
weeks.
2.1.6 Dietary studies
Short term: In a four week study, groups of rats fed diets
with thiometon at 0, 0.5, 2, or 5 ppm showed no effects upon plasma
cholinesterase activity, growth and behaviour. A slight inhibitory
effect on erythrocyte and brain cholinesterase activity was seen at
the highest dose level of 5 ppm. No observed effect level (NOEL) was
found to be 2 ppm.
In a 90 day study, groups of rats fed thiometon at 0, 5, 15 or
45 ppm showed mortality in the highest dose group after the fourth
week. Plasma and erythrocyte cholinesterase activity was depressed
in rats fed on a diet containing > 15 ppm of thiometon and
erythrocyte cholinesterase was only slightly inhibited in rats from
the 5 ppm group. No histopathological changes were found.
In a 90 day study, beagle dogs fed thiometon at 0, 10, 20 or 40
ppm (equivalent to 0, 0.35, 0.65 and 1.40 mg/kg/day respectively)
showed no effects on the amount of food consumed, growth,
histopathology or behaviour. In the highest dose group, depression
of plasma cholinesterase activity occurred towards the end of the
study. Erythrocyte cholinesterase activity was affected in rats fed
on a diet containing thiometon over 20 ppm. Brain cholinesterase
activity remained normal in all dose groups. NOEL was 10 ppm.
Long term: A two year rat feeding study was initiated at
doses of 0, 0.2, 1, 2 or 20 ppm. After six weeks the concentration
was increased to 0, 1, 2.5, 6.25 or 300 ppm respectively. Shortly
after increasing the dose levels, the rats fed on a diet containing
300 ppm lost weight and showed signs of acute poisoning and some
deaths occurred. In the survivors the body weight remained low
during the rest of the study due to decreased food and water
consumption. In females of this group, haemoglobin, mean corpuscular
volume and mean corpuscular haemoglobin levels were decreased as
well as blood glucose, protein and cholesterol. Plasma, erythrocyte,
and brain cholinesterases were strongly inhibited in both sexes at
this dose level. Lower values for plasma and erythrocyte
cholinesterase activities were occasionally observed in rats fed on
a diet containing 6.25 ppm thiometon. In rats on a diet of 2.5 ppm
erythrocyte cholinesterase activity was marginally reduced (<20%).
Erythrocytes, leukocytes as well as amorphous uric acid crystals
occurred in the urine at the highest dose level during the last half
of the study. The urine also had a higher specific gravity. Relative
organ weights were increased in the highest dose group save for the
spleen which had a decrease in relative weight, and the liver which
had a decreased relative weight in males only. No specific lesions
were induced at any dose level. NOEL was 2.5 ppm.
Dietary administration of 6, 12 or 48 ppm thiometon to dogs for
two years resulted in decreased cholinesterase activity in brain,
plasma and erythrocytes at 48 ppm and in erythrocytes and plasma.
(marginal decrease) at 12 ppm. No changes in mortality or in
histopathological, ophthalmological or behavioural parameters, nor
dose-related changes in urinalysis, haematological or clinical
chemistry parameters were observed. NOEL was 6 ppm.
2.1.7 Supplementary studies
Carcinogenicity: No tumours were found in the rat dietary
studies described above, that could be related to administration of
thiometon.
Mutagenicity: Thiometon was found to be mutagenic in
metabolically non-activated systems in several strains each of
Salmonella thyphimurium (his auxotrophs) G46, TA1530, TA1535, and
Escherichia coli causing base substitutions. Thiometon did not
demonstrate any mutagenic effect in two mouse micronucleus tests nor
in an Ames Salmonella/microsome plate test.
Teratogenicity: Female rabbits treated with thiometon at 1 or
5 mg/kg/day from the sixth to the eighteenth day of pregnancy showed
no evidence of teratogenic or embryotoxic effects.
Reproduction: A marginal effect on reproduction in rats was
reported following dietary administration of 6.25 ppm for three
generations. No adverse effects were noted at 1 or 2.5 ppm but at
6.25 ppm a lower lactation index, reduced viability, reduced pup
weight and/or an increase in stillborn births were observed in some
or all of the generations. There was no effect on gestation indices
and no adverse histopathological or teratogenic effects.
Neurotoxicity: Flaccid neuromuscular paralysis was observed
in rats 10-19 days after oral administration of 4-7 doses of
Intrathion, each 0.6 of the LD50, administered at three day
intervals. These events were paralleled by biochemical changes in
the spinal cord (Section 2.1.5). Examination of the spinal cord by
light and electron microscopy revealed demyelination and nerve cell
degeneration. In a special study in chickens, given thiometon
intramuscularly at a dose of 35 mg/kg, and protected with atropine
and pralidoxime, no signs of neurotoxicity were seen during an
observation period of 29 days.
2.2 TOXICOLOGY - MAN
2.2.1 Absorption route
Thiometon may be absorbed from the gastrointestinal tract,
through intact skin or from the lungs.
2.2.2 Dangerous doses
No published information available.
2.2.3 Observations on occupationally exposed workers
Twelve female agricultural workers exposed to Intrathion showed
changes in catalase, cytochrome oxidase and ceruloplasmin levels.
Some of these changes persisted for six months post-exposure. These
parameters are generally not examined for in cases of
organophosphorus poisoning and their interpretation is difficult.
Reduced blood cholinesterase activity has been reported in workers
during thiometon manufacture but there were no signs of illness.
2.2.4 Observations on exposure of the general public
No published information available.
2.2.5 Observations on volunteers
No published information available.
2.2.6 Reported mishaps
A 63 year old female ingested the equivalent to a full glass of
a 50% thiometon (Ekatin 50%) formulation. The victim experienced
painful abdominal cramps, diarrhoea, a weak and rapid pulse and cold
extremities. The victim vomited many times and was generally sleepy,
weak with extensive fasciculations visible on the trunk and limbs.
Tendon reflexes were elicitable and quadriceps muscle reflexes
lively. Plantar was of the flexor type. Neuromuscular synapse
insufficiency tests were normal but the victim had low blood
acetylcholinesterase activity. The dose was apparently non-fatal.
2.3 TOXICITY TO NON-MAMMALIAN SPECIES
2.3.1 Fish
LC50:
Rainbow trout 8.0 mg/L (96 hr)
Carp 13.2 mg/L (96 hr)
2.3.2 Birds
No published information available.
2.3.3 Other species
Thiometon was observed to be slightly toxic to Daphnia magna,
green algae, earthworms and bees.
3.0 REGULATORY AUTHORITIES: RECOMMENDATIONS ON REGULATION OF
COMPOUND
3.1 RECOMMENDED RESTRICTIONS ON AVAILABILITY
(For definition of categories see the Introduction to Data Sheets).
Liquid formulations of 600 g/L and over, Category 2
Other liquid formulations, Category 3
Solid formulations of 250 g/kg and over, Category 3
Other solid formulations, Category 4
3.2 TRANSPORTATION AND STORAGE
All formulations: Thiometon should be transported and stored
in clearly labelled impermeable containers, away from containers of
food and drink. Storage should be under lock and key, secure from
access by children and other unauthorized persons.
3.3 HANDLING
All formulations: Full protective clothing (see section 4.3)
should be used by those handling the compound. Adequate washing
facilities should be available at all times during the handling and
should be close to site of handling. Eating, drinking and smoking
should be prohibited during handling and before washing after
handling.
3.4 DISPOSAL AND/OR DECONTAMINATION OF CONTAINERS
All formulations: Containers must be firstly decontaminated
and then crushed and buried below topsoil. Care must be taken to
avoid subsequent contamination of water sources. Decontamination of
containers in order to use them for other purposes should not be
permitted.
3.5 SELECTION, TRAINING AND MEDICAL SUPERVISION OF WORKERS
All formulations: Pre-employment medical examination of
workers is necessary. Workers suffering from active hepatic or renal
disease should be excluded from contact with thiometon. A pre-
employment and periodic blood cholinesterase test for workers is
desirable. Special account should be taken of the workers' mental
ability to comprehend and follow instructions. Training of workers
in techniques to avoid contact is essential.
3.6 ADDITIONAL REGULATIONS RECOMMENDED IF DISTRIBUTED BY AIRCRAFT
All formulations: Pilot and loaders should have special
training in application methods and in recognition of the early
symptoms of poisoning. Protective clothing (Section 4.3) must be
worn. Flagmen, if used, should wear overalls, an impermeable broad
brimmed hat, impermeable boots and gloves, and a respirator, and be
located well away from the dropping zone.
3.7 LABELLING
Formulations in Category 2, Minimum Cautionary Statement
"DANGER - POISON"
(SKULL AND CROSS-BONES INSIGNIA)
Thiometon is a highly toxic organophosphorus compound which
inhibits cholinesterases. Contact with the skin, inhalation of dust
or spray, or swallowing may be fatal. Wear protective gloves, clean
protective clothing, and a respirator of the organic-vapour type
when handling this material. Wash immediately after handling. Ensure
that containers are stored under lock and key. Empty containers must
be decontaminated and disposed of in such a way so as to prevent all
possibility of accidental contact with them. Keep the material out
of reach of children and well away from foodstuffs, animal feed and
their containers. In case of contact, immediately remove
contaminated clothing and wash the skin thoroughly with soap and
water; for eyes, flush with water for 15 minutes.
If poisoning occurs, call a physician. Atropine and pralidoxime
are accepted antidotes, repeated doses may be necessary. Artificial
respiration also may be needed.
Formulations in Categories 3 and 4, Minimum Cautionary
Statement
"WARNING - POISON"
(SKULL AND CROSS-BONES INSIGNIA)
(for test of statement see above).
3.8 RESIDUES IN FOOD
Maximum residue levels
Maximum residue levels have been recommended by the Joint
FAO/WHO Joint Meeting on Pesticide Residues. Acceptable daily intake
for man has been estimated to be 0-0.003 mg/kg body weight.
4.0 PREVENTION OF POISONING IN MAN AND EMERGENCY AID
4.1 PRECAUTIONS IN USE
4.1.1 General
Thiometon, an organophosphorus pesticide is highly toxic to
mammals. Besides the oral route, it may be absorbed through the
intact skin and by inhalation of dust or spray mist. Repeated
exposure may have a cumulative inhibitory effect on cholinesterases.
Most formulations should be handled by trained personnel wearing
protective clothing.
4.1.2 Manufacture and formulations
For T.L.V. no information available.
Closed systems and forced ventilation are required to minimize
the exposure of workers to the chemical.
4.1.3 Mixers and applicators
When opening the container and when mixing, protective
impermeable boots, clean overalls, gloves and a respirator of the
organic-vapour type 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 respirator
should be worn, as well as an impermeable hat, protective clothing,
boots and gloves. The applicator should avoid working in spray mist
and avoid contact with the mouth.
Particular care is needed when equipment is being washed after
use. All protective clothing should be washed immediately after use,
including the insides of gloves. Splashes must be washed immediately
from the skin, or eyes, with large quantities of water. Before
eating, drinking or smoking, hands and exposed skin, should be
washed.
4.1.4 Other associated workers (including flagmen in aerial
operations)
Persons exposed to thiometon and associated with its
application should wear protective clothing and observe the
precautions described above in 4.1.3 under "Mixers and applicators".
4.1.5 Other populations likely to be affected
With good agricultural practices, subject to 4.2 below, other
persons should not be exposed to hazardous amounts of thiometon.
4.2 ENTRY OF PERSONS INTO TREATED AREA
Unprotected persons should be kept out of tall crops for four
days and out of other crops for 24 hours.
4.3 DECONTAMINATION OF SPILLAGE AND CONTAINERS
Residues in containers should be emptied in a diluted form into
a deep pit, and empty containers should be burned or buried, taking
care to avoid contamination of water sources. Re-use of empty
containers is prohibited (section 3.4). Spillage of thiometon 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 may include excessive sweating,
headache, weakness, giddiness, nausea, vomiting, hypersalivation,
stomach pains, blurred vision, slurred speech and muscle twitching.
Later there may be convulsions and coma in cases of severe
poisoning.
4.4.2 Treatment before person is seen by a physician, if these
symptoms appear following exposure
The person should stop work immediately, remove contaminated
clothing and wash the affected skin with water and soap, and flush
the area with large quantities of water. If swallowed, and if the
person is conscious, vomiting should be induced. In the event of
collapse, artificial resuscitation should be given, bearing in mind
that if mouth-to-mouth resuscitation is used, vomit may contain
dangerous amounts of thiometon.
5.0 FOR MEDICAL AND LABORATORY PERSONNEL
5.1 MEDICAL DIAGNOSIS AND TREATMENT IN CASES OF POISONING
5.1.1 General information
Thiometon is an organophosphorus pesticide, highly toxic to
mammals. It is readily absorbed from the gastrointestinal tract,
through the intact skin, and by inhalation of dust or spray mist. It
is converted in vivo to the oxygen analogues of thiometon which
are more potent inhibitors of cholinesterases.
5.1.2 Symptoms and signs
Initial symptoms and signs of poisoning may include excessive
sweating, headache, weakness, giddiness, nausea, hypersalivation,
vomiting, stomach pains, blurred vision, slurred speech and muscle
twitching. More advanced signs of poisoning may be convulsions coma,
loss of reflexes and loss of sphincter control.
5.1.3 Laboratory
The most important finding is reduction of activity of blood
cholinesterases. Urinary levels of organic phosphorus containing
metabolites may also be used as a measure of exposure. Neither
method is specific for thiometon.
5.1.4 Treatment
If the pesticide has been ingested, unless the patient is
vomiting, rapid gastric lavage should be performed using 5% sodium
bicarbonate. Care must be taken to avoid pulmonary complications
from solvents following ingestion of emulsifiable concentrate
formulations. For skin contact, the skin should be washed with water
and soap. If the compound has entered the eyes, they should be
washed with copious volumes of water or isotonic saline. Care must
be taken by the victims attendants to avoid their own intoxication
from contaminated clothing, skin or body fluids.
Persons without signs of respiratory insufficiency but with
manifest peripheral symptoms should be treated with 2-4 mg of
atropine sulfate by intravenous injection followed by 250 mg
toxogonin (adult dose) or 1 000 mg pralidoxime chloride (adult
dose), by slow intravenous injection. The additional therapy with
pralidoxime (or toxogonin) is likely to be successful if
administered within 24 hours of the onset of intoxication. However,
it may continue to be effective in the following days and treatment
should continue until no further benefit to clinical or biochemical
parameters is observed. More atropine may be given as needed.
Persons with severe intoxication, with respiratory difficulties,
cyanosis, convulsions or unconsciousness should immediately be given
oxygen and atropine sulfate followed by pralidoxime chloride. 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. Diazepam may be given to control convulsions. The
patient's condition should be carefully observed as a guide to
further administration of atropine. Symptoms will reappear if tissue
concentrations of thiometon or its metabolites remain high when the
effect of atropine wears off. Rales in the lung bases, myosis,
nausea, bradycardia, salivation or convulsions indicate inadequate
atropinization. Overdosage with atropine (pulse rate over 140, dry
mouth, flushed face) is rarely serious, but underdosage may be
fatal. The airways should be kept free and artificial resuscitation
should be applied if required, preferably by mechanical means. If
necessary intubation should be performed. Application of morphine,
aminophylline, phenothiazines, and reserpine is contraindicated. The
patient should not be allowed to return to work until blood
cholinesterase activity is over 80% of pre-exposure levels.
5.1.5 Prognosis
If the acute toxic episode is survived and if needed adequate
artificial resuscitation has been given, the chances of complete
recovery are good. However, in very severe cases, particularly if
artificial resuscitation has been inadequate, prolonged anoxia may
give rise to permanent brain damage.
5.1.6 References of previously reported cases
No published information available, other than case cited in
section 2.2.6.
5.2 SURVEILLANCE TESTS
Test Normal level* Action level* Symptomatic level*
Plasma 100% 50% variable
cholinesterase
Whole blood or 100% 70% usually 40%
erythrocyte
cholinesterase
5.3 LABORATORY METHODS
5.3.1 Detection and assay of compound
Urinary metabolites may also be determined in order to give an
indication of exposure. Thin-layer, gas and liquid chromatography
methods have been used to analyze thiometon in technical products
and in its formulations. Analysis of residues in plant and animal
tissues have been described by gas chromatography and flame
photometry methods.
Abbot, D.C., Crisp, S.S., Tarrant, V.R., Tatton, J. O'G.
(1970), Pestic. Sci 1, 10-13.
Wisson, M., van Hoek, C., Sauer, H.H. (1976), Anal. Methods
Pestic. Plant Growth Regul., 8, 239-244.
* Expressed as percentage of pre-exposure activity.
5.3.2 Other tests in case of poisoning
Activities of cholinesterases in the blood, provide the most
useful aid for diagnosis of poisoning, but are not specific for
thiometon intoxication.
REFERENCES
1. FAO Plant Production and Protection Paper, 20 sup. (1980),
Pesticide Residues in Food: 1979 Evaluations, pp. 503-512,
FAO, Rome
2. Farm Chemicals Handbook, (1984), Meister Publishing Co.,
Willoughby, Ohio 44094, USA
3. Hartley, D., Kidd, H., (1983), The Agrochemicals Handbook,
Royal Society of Chemistry. Unwin Bros. Ltd., Surrey, U.K.
4. Hayes, W.J. (1982), Pesticides Studied in Man. Williams and
Wilkins. Baltimore, USA, pp 377-379.
5. Jusic, A., Milic, S., (1978), Neuromuscular synapse testing in
two cases of suicidal organophosphorus pesticide
poisoning. Arch. Environ. Health, 33, 240-243.
6. Klotzche, C., (1964), Zur toxikologischen Prüfung neuer
insecticider Phosphorsäureester, Int. Archiv.
Gewerbepathologie Gewerbehygiene, 21, 92-106
7. Thomson, W.T. (1982), Agricultural Chemicals, Book 1.
Insecticides, 1982-1983 Revision. Thomson Publications
California 93791, USA.
8. Worthing, C.R. (ed) (1987). The Pesticide Manual. A World
Compendium. 8th Edition. British Crop Protection Council,
U.K.