WORLD HEALTH ORGANIZATION FOOD AND AGRICULTURE
ORGANIZATION
ORGANISATION MONDIALE DE LA SANTE ORGANISATION POUR L'ALIMENTATION
ET L'AGRICULTURE
VBC/DS/75.10
ORIGINAL: ENGLISH
DATA SHEETS ON PESTICIDES No. 10
June 1975
THALLIUM SULFATE
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.
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not constitute formal publication. Il ne doit faire
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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.
THALLIUM SULFATE
Part 1 - General information
CLASSIFICATION
Primary use: rodenticide
Secondary uses: insecticide
Chemical group: heavy metal salt
Data sheet No. 10
Date issued: June 1975
1.1 COMMON NAME: as the chemical name is short, no common name has
been established.
Identity: thallium sulfate
Tl2 SO4
Synonyms Local synonyms
thallous sulfate
1.2 SYNOPSIS: a heavy metal salt of high mammalian toxicity which is
used mainly as rodenticide. Its main hazard is as a chronic poison due
to its cumulation especially in liver, brain and skeletal muscle. It
is readily absorbed from the gastrointestinal tract and is also
absorbed through the intact skin.
1.3 SELECTED PROPERTIES
1.3.1 Physical characteristics: a colourless crystalline solid or
white powder m.p. 362°C. It is odourless.
1.3.2 Solubility: water at 20°C, 4.87%.
1.3.3 Stability: highly stable in solution under all conditions of
temperature and pH. Corrosive to zinc.
1.3.4 Vapour pressure (volatility) very low.
1.4 AGRICULTURE, HORTICULTURE AND FORESTRY
1.4.1 Common formulations
The technical material is incorporated into solid or liquid baits,
usually at concentrations of about 1% or less. Grain baits for rodent
control may contain up to 2%.
1.4.2 Susceptible pests
Main use is against rats. Also used to control mice, squirrels,
prairie dogs, moles and water voles. Its main insecticidal use is to
control ants and it is also used against cockroaches.
1.4.3 Use pattern
For rodent control baits are usually laid and removed after 24 hours.
In the United States of America regular "bait stations" are maintained
where rodents feed: they do not become bait-shy. Grain baits have been
distributed by aircraft for squirrel control. Ants are controlled in
the United States of America by sweet baits containing 0.5% thallium.
Thallium sulfate is normally used only by pest control operators or
other trained personnel and in many countries its sale and use are
legally restricted.
1.4.4 Unintended effects
Livestock, domestic animals and wildlife have been poisoned.
Carnivorous mammals and predatory and scavenger birds (especially
eagles) have been killed by secondary poisoning, sheep by eating bait,
and grain-eating birds and mammals by eating thallium-treated grain
used for squirrel control.
Thallium sulfate is a cumulative soil sterilant. It is extremely
phytotoxic and inhibits germination of seeds.
1.5 PUBLIC HEALTH PROGRAMME
Has been used for commensal rodent control but is considered too
toxic for use where non-target animals or man may come in contact.
1.6 HOUSEHOLD USE
The chronic hazard and very dangerous properties of thallium sulfate
make it unsafe for household use except by professional pest control
operators in special circumstances. In many countries, strict control
of the sale and use of the compound prevent its application in any
other way.
THALLIUM SULFATE
Part 2 - Toxicology and risks
Common name: thallium sulfate
Data sheet No. 10
Date issued: June 1975
2.1 TOXICOLOGY - MAMMALS
2.1.1 Absorption route: the oral route is the most important in cases
of poisoning; however, dermal absorption may occur. Solutions of
thallium salts in water are tasteless, hence the opportunities for
accident or misuse.
2.1.2 Mode of action: unknown, although there is some suggestion that
it may interfere with the metabolism of potassium inside cells.
2.1.3 Excretion products: excreted as thallium salts mainly by the
kidney, but also to some extent into the intestine.
2.1.4 Toxicity, single dose
Oral: LD50 rat (M): 10.6 mg/kg
Dermal: LD50 rat (M)14 hours: > 1000 mg/kg.
7 days: 500 mg/kg
Inhalation: not known
Most susceptible species: not known
2.1.5 Toxicity, repeated doses
Oral: Rat: the daily oral administration of thallium acetate to
rats at less than 1/50 of the single LD50 caused depilation in
six weeks and death within four months.
Dermal: no information.
Inhalation: no information.
Cumulation of compound: thallium is cumulative in all tissues
of the body, especially in liver, brain and skeletal muscle.
About 70% of a given dose is excreted in one month.
Cumulation of effect: the chronic toxicity of thallium is due
to the cumulation of the element in the body.
2.1.6 Dietary studies
Short-term: no information.
Long-term: no information.
2.1.7 Supplementary studies of toxicity: no information.
2.1.8 Modifications of toxicity: no information.
2.2 TOXICOLOGY - MAN
2.2.1 Dangerous doses
Single: the fatal dose is reported to be < 500 mg.
2.2.2 Observations of occupationally exposed workers: no information.
2.2.3 Observations on exposure of the general population: no
information.
2.2.4 Observations of volunteers: no information.
2.2.5 Reported mishaps
Of 778 cases of thallium poisoning reported, 6% were fatal. Thallium
acetate was formerly used as a depilatory in children at a single oral
dose of 8 mg/kg. Serious poisoning including six deaths was found in
5.5% of 8006 cases.
By repeated testing of the urine of 193 patients with accelerated
hair loss, 43 cases of mild chronic thallotoxocosis were found. The
apparent sources were the home use of thallium by professional
exterminators and patients and by the ingestion of contaminated foods.
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 needs for special
precautions.
2.3.1 Fish
Moderately toxic to some species.
2.3.2 Birds
Poisonous to birds. Direct poisoning of grain-eating birds by treated
grain used for squirrel control has occurred. Predatory and scavenger
birds can be killed by secondary poisoning.
2.3.3 Other species
Data on other non-mammalian species are lacking. There should be no
hazard in practice owing to the very restricted conditions of
recommended use.
THALLIUM SULFATE
Part 3 - For regulatory authorities
Common name: thallium sulfate
Data sheet No. 10
Date issued: June 1975
RECOMMENDATIONS ON REGULATION OF COMPOUND
3.1 RECOMMENDED RESTRICTIONS ON AVAILABILITY
(For definition of categories see introduction.)
All formulations: category 2.
3.2 TRANSPORTATION AND STORAGE
All formulations
Should be transported or stored in clearly labelled impermeable
containers under lock and key, secure from access by unauthorized
persons and children. No food or drink should be transported or stored
in the same compartment.
3.3 HANDLING
All formulations
Full protective clothing (see Part 4) should be provided for all
handling of the compound. Adequate washing facilities should be
available at all times during handling and should be close to the site
of handling and before washing after handling. Baits of thallium
sulfate should be removed and the area thoroughly cleaned up after the
necessary purpose has been fulfilled.
3.4 DISPOSAL AND/OR DECONTAMINATION OF CONTAINERS
All formulations
Container must either be burned or 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
Factory workers and formulations: pre-employment medical examination
of workers necessary. Regular periodic special medical examinations
advisable. Special account should be taken of the workers' mental
ability to comprehend and follow instructions. Training of workers in
techniques to avoid contact essential.
Field workers: regular special medical examination advisable but
often not practical as a routine. Training of workers in techniques to
avoid contact essential.
3.6 ADDITIONAL REGULATIONS RECOMMENDED IF DISTRIBUTED BY AIRCRAFT
Not applicable.
3.7 LABELLING
All formulations
Minimum cautionary statement:
"POISON"
(Skull and crossbones insignia)
"Thallium sulfate is a highly toxic heavy metal salt which is
cumulative in body tissues. It is poisonous if swallowed and may
be absorbed through the skin. Avoid skin contact; wear
protective gloves and clean protective clothing when handling
this material. Bathe immediately after work.
Ensure that containers are stored under lock and key. Empty
containers must be disposed of in such a way as to prevent all
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."
3.8 RESIDUES IN FOOD
Levels have not been recommended by the Joint FAO/WHO meeting on
Pesticide Residues. If used correctly as a bait, residues of thallium
will not appear in human food.
THALLIUM SULFATE
Part 4 - Prevention of poisoning in man and emergency aid
Common name: thallium sulfate
Data sheet No. 10
Date issued: June 1975
4.1 PRECAUTIONS IN USE
4.1.1 General
Thallium sulfate is a heavy metal salt of high toxicity which is
cumulative in body tissues. Most formulations should be handled by
trained personnel wearing protective clothing.
4.1.2 Manufacture and formulation
TLV
ACGIH 0.1 mg/m3; USSR 0.01 mg/m3 (bromide or iodide only
specified).
Closed systems and forced ventilation may be required to reduce as
much as possible the exposure of workers to the chemical. All
formulations should be coloured with a warning dye.
4.1.3 Mixers and applicators
When opening the container and when mixing, protective impermeable
boots, clean overalls, gloves and a face mask should be worn. Mixing,
if not mechanical, should always be carried out with a paddle of
appropriate length. The applicator should avoid inhaling dust
particles and avoid contact with the mouth. Particular care is needed
when the 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
other exposed skin should be washed.
Thallium sulfate should not be used in dwelling houses. Baits should
not be used where there is risk of contaminating food, animal feeding
stuffs or drinking or washing water. Exposed baits should be laid in
containers clearly marked "Poison". Baits should not be laid unless
all access by children and animals other than rats and mice can be
prevented. Except in locked unoccupied premises baits should not
remain down for more than 24 hours. All exposed baits and their
containers should be removed after treatment and burned. Rodent bodies
should be searched for and destroyed by burning.
4.1.4 Other associated workers (including flagmen in aerial operations)
Not applicable.
4.1.5 Other populations likely to be affected
With correct use as described under mixers and applicators (4.1.3
above) other populations should not be exposed to hazardous amounts of
thallium sulfate.
4.2 ENTRY OF PERSON INTO TREATED AREAS
Adults may enter premises where baits have been laid provided
sufficient warning has been given and all exposed baits are marked
"Poison".
4.3 SAFE DISPOSAL OF CONTAINERS AND SPILLAGE
Residues in containers should be emptied in a diluted form into a
deep pit taking care to avoid contamination of ground waters.
Decontamination of containers in order to use them for other purposes
should not be permitted. Spillage should be removed as much as
possible into a deep dry pit and the remainder washed away with large
quantities of water.
4.4 EMERGENCY AID
4.4.1 Early symptoms of poisoning
Signs and symptoms of acute thallium poisoning are referrable mainly
to the gastrointestinal tract and nervous system. After large doses,
gastroenteritis is evident in about 12-14 hours while neurological
symptoms may be delayed two to five days. Gastrointestinal
manifestations include severe paroxysmal abdominal pain, vomiting,
diarrhoea, anorexia, stomatitis, salivation and weight loss.
Neurological manifestations during the first days of illness may
include paresthesias, headache, cranial nerve damage, convulsions,
delirium and coma.
In chronic poisoning symptoms can be non-specific except for loss of
hair which occurs, and which is very specific for thallium
intoxication.
4.4.2 Treatment before person is seen by a physician, if these symptoms
appear following exposure
Due to the delayed appearance of symptoms it is unlikely that
specific symptoms will be seen directly following exposure. If
swallowed vomiting should be induced if the person is conscious.
THALLIUM SULFATE
Part 5 - For medical and laboratory personnel
Common name: thallium sulfate
Data sheet No. 10
Date issued: June 1975
5.1 MEDICAL DIAGNOSIS AND TREATMENT OF CASES OF POISONING
5.1.1 General information
A heavy metal salt of high toxicity which is especially hazardous
because of its cumulative properties. The element tends to concentrate
in liver, brain and skeletal muscle. It is readily absorbed from the
gastrointestinal tract and may also be absorbed through the intact
skin.
5.1.2 Symptoms and signs
Signs and symptoms are referable mainly to the gastrointestinal tract
and nervous system. After large doses, gastroenteritis is evident in
about 12 to 14 hours, while neurological symptoms may be delayed two to
five days. Gastrointestinal manifestations include severe paroxysmal
abdominal pain, vomiting, diarrhoea, anorexia, stomatitis, salivation,
and weight loss. Neurological manifestations during the first days of
illness may include paresthesias, headache, cranial nerve damage,
convulsions, delirium and coma. Vascular collapse and death may occur
in 24 to 48 hours, but the course is usually more prolonged. Death may
be caused by respiratory paralysis, pneumonia, or circulatory
disturbances. Peripheral neuropathy, particularly in the legs, is
common with severe pain, paresthesias, muscle weakness, and atrophy.
Loss of hair begins after one to two weeks have elapsed. In the more
protracted cases, ataxia, choreiform movements, dementia, depression,
and psychosis may be prominent. A blue gingival line and
dermatological abnormalities, including white bands in the nails may
appear. Neurologic damage may be permanent. Liver damage occurs but
is not prominent clincally. Kidney damage is manifested by
proteinuria, cylindruria, and sometimes oliguria and haematuria.
With the continued administration of smaller doses, symptoms may
first be apparent in a week with progression for several more weeks. In
chronic poisoning, symptoms can be nonspecific and thallium
intoxication may not be suspected unless depilation occurs. Although
characteristic of thallium toxicity, hair loss also can result from
poisoning with other metals and certain drugs.
5.1.3 Laboratory
Diagnosis can be confirmed by analysis for thallium in urine, blood, or
hair. Thallium does not occur normally in body fluids or tissue;
however, its presence in urine does not necessarily mean intoxication.
In fatal, acute and subacute cases, the concentration of thallium in
tissue ranges from five to 100 ppm. Thallium can be found in the urine
for as lone as two months after intoxication. Other laboratory
determinations are not specific. The blood picture and the
cerebrospinal fluid are usually normal. Tests of liver function have
been abnormal in a few instances.
5.1.4 Treatment
If an acute dose of thallium sulfate has been ingested, gastric lavage
should be done with 2-4 l of water. Activated charcoal and potassium
iodide should be given orally to reduce thallium absorption. Sodum
thiosulfate may be given intravenously to inactivate any thallium in
the blood but its usefulness has not been proved. The value of
chelating agents is questionable. It is generally felt that EDTA or
BAL are not useful in treatment of thallium intoxication. However,
dithizon (diphenylthiocarbazone) 10 mg/kg twice a day for four days or
longer has been effective. Other recommended forms of treatment
include haemodialysis and forced diuresis and administration of
Prussian Blue.
5.1.5 Prognosis
Prognosis depends largely upon the severity of the intoxication and
also the nature. If the effects of an acute dose are overcome, the
chances of complete recovery are good. However, neurological damage
may be permanent in severe cases.
5.1.6 References of previously reported cases
The following references give methods of treatment used in cases of
poisonings:
Hayes, W. J., jr (1963) Clinical handbook on economic poisons, U.S.
Publ. Hlth Ser. Publn., No. 476, p. 84
Mathews, J. & Anzarat, A. (1968) Canad. Med. Ass. J., 99, 72-75
Piazolo, H. E. et al. (1971) Deutsche Medizinische Wochenschrift 96,
1217, Van der Merwč, C. F. (1972) Sth Afr. med. J., 46, 960
5.2 SURVEILLANCE METHODS
Urinary levels of thallium in the range of 0.5-7.5 ppm have been
reported as being indicative of poisoning.
5.3 LABORATORY METHODS
References only are given.
5.3.1 Detection and analysis
A number of simple methods are briefly outlined by Anderson (1953).
A colorimetric method for determining thallium in urine is described
by Ariel & Bach (1963) and a rapid spectrographic determination by
Farhan et al. (1969).
A very sensitive method enabling the determination of 3 µg of
thallium in 50-100 µl of urine is given by Curry et al. (1969).
5.3.2 Other tests in cases of poisoning
None.
REFERENCES
Anderson, J. R. A. (1953) Detection and determination of thallium,
Analyt. Chem., 25, 108
Ariel, M. & Bach, D. (1963) The determination of thallium in urine,
Analyst, 88, 30
Farhan, F. M., Eyvani, J. & Atabakhsh, J. (1969) Direct spectrographic
determination of traces of thallium in urine, Toxicol. Appl.
Pharmacol., 15, 493
Curry, A. S., Read, J. F. & Knott, A. R. (1969) Determination of
thallium in biological material by flame spectrophotometry and
atomic absorption, Analyst, 94, 744