Health and Safety Guide No. 85
HEALTH AND SAFETY
This is a companion volume to
Environmental Health Criteria 158: Amitrole
Published by the World Health Organization for the International
Programme on Chemical Safety (a collaborative programme ofthe United
Nations Environment Programme, the International Labour Organsation,
and the World Health Organization)
WORLD HEALTH ORGANIZATION, GENEVA 1994
This report contains the collective views of an international group of
experts and does not necessarily represent the decisions or the stated
policy of the United Nations Environment Programme, the International
Labour Organisation, or the World Health Organization
WHO Library Cataloguing in Publication Data
Health and safety guide for amitrole.
(Health and safety guide ; no. 85)
1.Aniitrole - standards I.Series
ISBN 92 4 151085 4 (NLM Classification: WA 240)
The World Health Organization welcomes requests for permission to
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© World Health Organization 1994
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1. PRODUCT IDENTITY AND USES...............................
1.2 Physical and chemical properties.................
1.3 Analytical methods...............................
1.4 Production and uses..............................
2. SUMMARY AND EVALUATION..................................
2.1 Identity, physical and chemical properties, and
2.2 Sources of human and environmental exposure......
2.3 Environmental transport, distribution,
2.4 Environmental levels and human exposure..........
2.5 Kinetics and metabolism in laboratory animals
2.6 Effects on experimental animals and in vitro
2.7 Effects on humans................................
2.8 Effects on other organisms in the laboratory and
2.9 Evaluation of human health risks and effects
on the environment...............................
2.9.1 Evaluation of human health risks...........
2.9.2 Evaluation of effects on the environment...
3. CONCLUSIONS AND RECOMMENDATIONS.........................
3.2 Recommendations for the protection of human health
and the environment..............................
4. HUMAN HEALTH HAZARDS, PREVENTION AND
PROTECTION, EMERGENCY ACTION............................
4.1 Human health hazards, prevention and
protection, first aid............................
4.1.1 Advice to physicians......................
4.1.2 Health surveillance advice................
4.2 Explosion and fire hazards.......................
5. HAZARDS FOR THE ENVIRONMENT AND THEIR
6. SUMMARY OF CHEMICAL SAFETY INFORMATION..................
7. CURRENT REGULATIONS, GUIDELINES, AND
7.1 Previous evaluations by international bodies.....
7.2 Exposure limit values............................
7.3 Specific restrictions............................
7.4 Labelling, packaging, and transport..............
7.5 Waste disposal...................................
The Environmental Health Criteria (EHC) monographs produced by the
Intemational Programme on Chemical Safety include an assessment of the
effects on the environment and on human health of exposure to a
chemical or combination of chemicals, or physical or biological agents.
They also provide guidelines for setting exposure limits.
The purpose of a Health and Safety Guide is to facilitate the
application of these guidelines in national chemical safety programmes.
The first three sections of a Health and Safety Guide highlight the
relevant technical information in the corresponding EHC. Section 4
includes advice on preventive and protective measures and emergency
action; health workers should be thoroughly familiar with the medical
information to ensure that they can act efficiently in an emergency.
Within the Guide is a Summary of Chemical Safety Information which
should be readily available, and should be clearly explained, to all
who could come into contact with the chemical. The section on
regulatory information has been extracted from the legal file of the
Intemational Register of Potentially Toxic Chemicals (IRPTC) and from
other United Nations sources.
The target readership includes occupational health services, those in
ministries, governmental agencies, industry, and trade unions who are
involved in the safe use of chemicals and the avoidance of
environmental health hazards, and those wanting more information on
this topic. An attempt has been made to use only terms that will be
familiar to the intended user. However, sections 1 and 2 inevitably
contain some technical terms. A bibliography has been included for
readers who require further background information.
Revision of the information in this Guide will take place in due
course, and the eventual aim is to use standardized terminology.
Comments on any difficulties encountered in using the Guide would be
very helpful and should be addressed to:
International Programme on Chemical Safety
World Health Organization
1211 Geneva 27
THE INFORMATION IN THIS GUIDE
SHOULD BE CONSIDERED AS A
STARTING POINT TO A COMPREHENSIVE
HEALTH AND SAFETY PROGRAMME
1. PRODUCT IDENTITY AND USES
Common name: amitrole
Molecular formula: C2H4N4
Common synonyms: aminotriazole; 2-aminotriazole; 3-aminotriazole;
3-amino-lH-1,2,4-triazole; AT; 3AT; ATA;
3,A-T; ATZ; AT-90; triazolamine;
Common trade Amerol; Aminotriazole Weedkiller 90;
names: Aminotriazol Spritzpulver; Amitril; Aniitril
T.L.; Amitrol; Amitrol 90; Amitrol Plus;
Amitrol-T; Amizine; Aniizol; Amizol DP;
Amizol F; AT Liquid; Azaplant; Azolan; Azole;
Azaplant Kombi; Campaprim A1544; Cytrol;
Cytrole; Destructol; Diurol 5030; Domatol;
Domatol 88; Elmasil; Emisol; Emisol 50;
Emosol F; ENT 25445; Exit; Fenaniine;
Fenavar; Fyrbar; Kleer-Lot; Lancer; Nu-Zinole
AA; Orga 414; Pre-Ceed; Radoxone TL;
Ramizol; Sapherb; Solution Concentree T271;
Ustinex; Vorox; Vorox AA; Vorox AS; Weedar
ADS; Weedar AT; Weedazin; Weedazin
Arginit; Weedazol; Weedazol GP2; Weedazol
Super; Weedex Granulat; Weedoclor; X-All
CAS chemical IH-1,2,4-triazol-3-amine (9CI)
IUPAC names: 1H-1,2,4-triazol-3-ylamine
Technical grade amitrole contains a minimum of 95 % active ingredient
and is formulated as a 250 g/litre solution in water, usually with an
equimolar concentration of ammonium thiocyanate, or as a 400 g/kg
wettable powder, usually in combination with other herbicides.
1.2 Physical and Chemical Properties
Amitrole is readily soluble in water, methanol, ethanol, and
chloroform, sparingly soluble in ethyl acetate, and insoluble in
hydrocarbons, acetone, and ether. It forms salts with most acids and
bases, and is a powerful chelating agent. It is corrosive to
aluminium, copper, and iron.
Further physical and chemical properties of amitrole are given in the
"Summary of Chemical Safety Information" (section 6).
1.3 Analytical Methods
Numerous analytical methods have been described for the detection of
amitrole. Early methods using paper chromatography for the detection
of amitrole in plants have been largely replaced by column
chromatography and gas chromatography. Other methods include thin-
layer chromatography, high-pressure liquid chromatography, and
1.4 Production and Uses
Amitrole was first synthesized in 1946, and was commercialized in the
1950s. It is a non-selective herbicide, effective against a very wide
spectrum of annual and perennial broad-leaf and grass-type weeds. Its
activity is enhanced by the addition of ammonium thiocyanate. It is
commonly used as a brush killer, or against non-woody weeds around
established apple and pear trees. It is also used on fallow land
before planting kale, maize, oilseed rape, potatoes, or wheat. It is
also used along roadsides and railway lines and for the control of pond
weeds. Amitrole is not approved for use on food plants.
2. SUMMARY AND EVALUATION
2.1 Identity, Physical and Chemical Properties, and Analytical
Amitrole (3-amino-1,2,4-triazole) is a colourless, crystalline powder.
It is thermally stable, and has a melting point of 156-159 °C. It is
readily soluble in water and ethanol and only sparingly soluble in
organic solvents, such as hexane and toluene. Chemically, amitrole
behaves as a typical aromatic amine, as well as an S-triazole. A wide
range of analytical methods are available for the detection and
quantification of amitrole in plants, soil, water, air, and urine.
2.2 Sources of Human and Environmental Exposure
Amitrole does not occur naturally. It is manufactured by the
condensation of formic acid with aminoguanidine bicarbonate in an inert
solvent at 100-200 °C. It is used as a herbicide with a wide spectrum
of activity and appears to act by inhibiting the formation of
chlorophyll. It is commonly used around orchard trees, on fallow land,
along roadsides and railway lines, or for pond weed control.
2.3 Environmental Transport, Distribution, and Transformation
Amitrole does not enter the atmosphere because of its low vapour
pressure. It is readily soluble in water, with a photodegradation
half-life of more than one year in distilled water. Photodegradation
does occur in the presence of the photosensitizer, humic acid potassium
salt, reducing the half-life to 7.5 h.
Amitrole is adsorbed on soil particles and organic matter by proton
association. The binding is reversible and not strong, even under
favourable acid conditions. Measured Koc values classify amitrole as
"highly mobile" in soils of pH > 5 and "medium to highly mobile" at
lower pH. There is considerable variation in the leaching of the parent
compound through experimental soil columns. Generally, movement is
most readily seen in sands; increased organic matter content reduces
Degradation in soils is usually fairly rapid, but varies with soil type
and temperature. Microorganisms (bacteria) that are capable of
degrading amitrole have been isolated. The herbicide can act as sole
nitrogen source, but not also as a sole carbon source, for the
bacteria. Microbial degradation is probably the major route of
breakdown of amitrole; little or no breakdown has been recorded in
studies with sterilized soil. However, abiotic mechanisms, including
the action of free radicals, have also been proposed for degradation.
Laboratory studies have indicated degradation to CO2, with half-lives
of between 2 and 30 days. The results of a single field study suggest
that degradation may take longer at lower temperatures and different
soil moisture levels; the half-life was about 100 days in a test clay.
Although the parent compound leaches through some soils, degradation
products are tightly bound to soil. Since amitrole is degraded rapidly
in soil, the high potential of the herbicide to leach does not seem to
occur in practice. Occasional damage to trees, reported in early
usage, has not been a regular feature of the use of amitrole.
When applied to vegetation, amitrole is absorbed through foliage and
can be translocated throughout the plant. It is also absorbed through
roots and transported via the xylem to the shoot tips within a few
High water solubility, a very low octanol-water partition coefficient,
and non-persistence in animals mean that there is no possibility of
bioaccumulation of amitrole, or of transport through food-chains.
2.4 Environmental Levels and Human Exposure
Particulates containing amitrole may be released from production
plants; atmospheric levels of 0-100 mg/m3 have been measured close to
The use of amitrole in waterways and watersheds has led to transitory
water concentrations of up to 150 µg/litre. Concentrations in running
water fall rapidly to nondetectable levels (< 2 µg/litre) within 2 h.
Application to ponds gave an initial water concentration of 1.3
mg/litre, falling to 80 µg/litre after 27 weeks. Close to a production
plant, river concentrations ranged from 0.5 to 2 mg/litre.
No residues of amitrole have been detected in food following
recommended use. Spraying of ground cover around fruit trees did not
lead to residues in apples. Wild growing fruit in the vicinity of
control areas can develop residues.
There have been no reports of amitrole in drinking-water.
2.5 Kinetics and Metabolism in Laboratory Animals and Human
Following oral administration, amitrole was readily absorbed from the
gastrointestinal tract of mammals. The compound is rapidly excreted
from the body, mainly as the parent compound. The main route of
excretion in humans and laboratory animals is via the urine, and the
majority of excretion takes place during the first 24 h. Metabolic
transformation in mammals produces two minor metabolites detectable in
the urine of experimental animals. When amitrole aerosol is inhaled, a
similar rapid excretion via the urine takes place.
2.6 Effects on Experimental Animals and In Vitro Test Systems
Amitrole has a low acute toxicity when tested in several species, by
various routes of administration (LD50s always higher than 2500 mg/kg
body weight). Amitrole was found to affect the thyroid after single,
short, or long-term exposures. Amitrole is goitrogenic, causing
thyroid hypertrophy and hyperplasia, depletion of colloid, and
increased vascularity. In long-term studies, these changes precede the
development of thyroid neoplasia in rats.
The carcinogenic effects of amitrole on the thyroid are thought to be
related to its inhibitory effects on thyroid hormone synthesis,
resulting in increased TSH levels and, consequently, continuous
stimulation of the gland.
Equivocal results in some tests have been reported on the genotoxic
potential of amitrole. In carcinogenicity testing on rats, amitrole
does not induce tumours in organs other than the thyroid. However, a
high dose of amitrole given to mice caused liver tumours.
Several criteria have been used to assess the early effects of amitrole
on the thyroid. The lowest NAOEL derived from these studies was 2
mg/kg in the diet of rats, and assessed on the basis of thyroid
2.7 Effects on Humans
A single case of contact dermatitis by amitrole has been reported.
Amitrole did not cause toxic effects when ingested at a dose of 20
mg/kg. In a controlled study, 100 mg amitrole was found to inhibit
iodine uptake by the thyroid at 24 h. Weed control operators exposed
dermally to approximately 340 mg amitrole per person per day, for 10
days, had no changes in thyroid function.
2.8 Effects on Other Organisms in the Laboratory and Field
Several studies on the growth of cyanobacteria have shown no effect at
concentrations at, or below, 4 mg/litre. No consistent adverse effects
on nitrogen fixation have been reported. Bacteria from soil were
unaffected by concentrations of 20 mg/litre medium, for nitrogen-fixing
Rhizobiwn, and 150 mg/kg, for cellulolytic bacteria. There were no
effects on nitrification or soil respiration at 100 mg a.i./kg dry
soil, five times the maximum recommended application rate. Reduced
nodulation in sub-clover was reported at lower concentrations, up to 20
mg/litre, in culture.
Various unicellular algae have been tested for the growth effects of
amitrole. At 0.2-0.5 mg/litre, the growth of Selenastrwn was reported
to be the most sensitive.
Most aquatic invertebrates have shown a high tolerance to technical
amitrole: LC50s were > 10 mg/litre for all organisms other than the
water flea, Daphnia magna, widi an acute 48-h EC50 (immobilization) of
1.5 mg/litre. Fish and amphibian larvae are also tolerant to amitrole,
with LC50s of > 40 mg/litre. Longer-term studies indicated that young
rainbow trout survive concentrations of amitrole of 25 mg/litre for 21
Two earthworm species (Eisenia and Allolobophora) were unaffected by
soil concentrations of amitrole (SP50) and Amitrole T of 100 and 1000
mg/kg, respectively. Carabid beetles were unaffected after direct
spraying with amitrole at rates equivalent to 30 kg/ha. Effects on
nematodes only occurred at high concentrations of amitrole (LC50 184
mg/kg). Amitrole was "non-hazardous" to bees in field trials.
The toxicity of amitrole for birds is low, with all reported dietary
LC50s being > 5000 mg/kg. Acute oral dosing did not kill any mallard
ducks at 2000 mg/kg body weight.
2.9 Evaluation of Human Health Risks and Effects on the Environment
2.9.1 Evaluation of human health risks
General population exposure to amitrole is expected to be minimal,
given that it does not persist in the environment, and residues should
not occur in food crops. Levels in drinking-water supplies would be
expected to be extremely low.
Occupational exposure for weed control operators occurs via the dermal
and inhalation routes. However, the results of animal studies and
human data indicate that dermal absorption of amitrole is low.
Inhalational exposure would be minimized by appropriate breathing
In both animals and humans there is a rapid excretion of unchanged
amitrole following systemic exposure. Amitrole does not have any
teratogenic effects and does not affect reproduction.
The main effect of amitrole in short- and long-term studies on rats is
on the thyroid. Amitrole inhibits the production of thyroid hormones
T3 and T4, thereby stimulating the pituitary gland to produce more TSH,
which in turn activates the thyroid. Consequently thyroid weight
increases and the thyroid becomes hyperplastic and hypertrophic. These
effects are reversible upon cessation of exposure, even though the
extent of this reversal is undefined. Thyroid tumours occur only with
long-term exposure at relatively high dose levels in animals already
affected by thyroid changes. The mechanism of neoplastic
transformation is not understood. However, from all available studies
it is clear that hyperplasia always precedes neoplasia, because no
tumours are found when the thyroid is not affected. The results of
mutagenicity studies are either negative or conflicting and therefore
the evidence for amitrole genotoxicity is equivocal. On this basis, it
can be concluded that 2 mg/kg diet (equivalent to 0.1 mg/kg body weight
per day) is a no-effect level, based on thyroid hyperplasia and iodine
uptake, and this value can be used to establish a safe dose for humans.
In carcinogenicity studies on rats, amitrole did not induce tumours in
organs other than the thyroid. However, in some mouse studies with
high dose levels, liver tumours were also found. Because the mouse is
very sensitive to the induction of liver tumours and the dosages are
far above any potential exposure of humans, this is considered of
little consequence for the human risk evaluation.
Under normal occupational exposure conditions, it is unlikely that
amitrole induces thyroid effects in humans.
Finally, it should be noted that the role of TSH in thyroid
carcinogenesis in humans seems to differ from that played in
experimental thyroid cancer in rats. This is based on the absence of a
correlation between hypothyroidism and thyroid cancer in human
2.9.2 Evaluation of effects on the environment
Amitrole has a high potential mobility in soil. The rapid degradation
of amitrole in soil, and its retention in most soils by adsorption,
makes this potential very unlikely to be realized in most situations.
The few reports of effects on non-target vegetation support this view.
Use of amitrole at maximum recommended application rates to control
terrestrial weeds would lead to soil residues of up to 20 mg a.i./kg
dry soil. Effects on soil microorganisms would not occur at these
levels, and soil invertebrates have not been adversely affected at
substantially higher concentrations. Amitrole does not present a
hazard for birds.
Overspraying of static water bodies during the control of terrestrial
weeds would lead to maximum initial water concentrations substantially
below reported NOECs for aquatic organisms. Use of amitrole to control
aquatic weeds has been reported to lead to water concentrations of
about 1 mg/litre that persist for some time. This would not affect
fish but could be expected to adversely affect water fleas (NOEC 0.2
mg/litre for reproductive effects).
3. CONCLUSIONS AND RECOMMENDATIONS
Amitrole does not present a significant risk for human health, when
manufactured and used within the confines of good handling procedures.
Current restrictions on its use in most countries, particularly its
restriction to non-crop uses, will ensure minimum human exposure.
Amitrole is relatively rapidly degraded in the environment with no
evidence of bioaccumulation. The available data do not indicate that
there are significant effects on the environment. Any effects that do
occur appear to be transient.
3.2 Recommendations for the Protection of Human Health and the
Annual monitoring of thyroid function is recommended in workers
regularly involved with amitrole, both at the formulation or
Epidemiological studies should be continued on workers exposed to
Use patterns should continue to avoid the risk of contamination of food
crops and water supplies, and limits for residues in food and water
should be maintained at low levels, e.g., below 0.02 mg/kg in raw
agricultural commodities of plant origin (level at, or about, the limit
4. HUMAN HEALTH HAZARDS, PREVENTION
AND PROTECTION, EMERGENCY ACTION
4.1 Human Health Hazards, Prevention and Protection, First Aid
The oral and dermal toxicities of amitrole for mammals are low (rat
oral LD50 > 4000 mg/kg, rat dermal LD50 > 2500 mg/kg). An accidental
ingestion case (estimated dose 20 mg/kg) produced no clinical symptoms.
The potential for skin and eye irritation is slight. A single case
study indicated some potential for skin sensitization.
The major health hazard of amitrole is thought to be associated with
its goitrogenic activity. Amitrole has the ability to induce thyroid
tumours in rats following prolonged exposure, and prolonged thyroid
Poisoning by amitrole is unlikely to cause any immediate adverse
symptoms. In cases of ingestion, medical attention should be sought.
4.1.1 Advice to physicians
The acute toxicity of amitrole for humans is believed to be low. There
is no specific antidote. Treat symptomatically when required. Emesis
may be indicated, if a large quantity has been ingested.
If ingestion or inhalation of formulations contain ammonium thiocyanate
has occurred, the ammonium thiocyanate would be of more serious
toxicological concern than the amitrole. In cases of substantial,
recent ingestion, emesis or gastric lavage may be indicated.
Haemodialysis is the mainstay of treatment for accidental overdosage
4.1.2 Health surveillance advice
Excessive occupational exposure to amitrole may be monitored by means
of thyroid function tests (plasma T3 and T4 levels and TSH).
4.2 Explosion and Fire Hazards
Most amitrole formulations do not burn. When strongly heated, amitrole
emits highly toxic fumes. Use dry powder, carbon dioxide, alcohol-
resistant foam, sand, or earth for dealing with fires. DO NOT use
water. Cool nearby drums containing amitrole with water spray.
Technical amitrole and its formulations should be stored in locked,
well-ventilated buildings, preferably specifically used for pesticide
storage. Keep products out of reach of children and unauthorized
personnel. Do not store near animal feed or foodstuffs.
Comply with any local regulations regarding the movement of hazardous
goods. Do not load with animal feed or foodstuffs. Before dispatch,
ensure that the containers are sound and that labels are securely fixed
Avoid excessive exposure. Keep spectators away from any spillage.
Prevent contamination of nearby vegetation and waterways.
Absorb spilled liquid with earth or sand. If available, sawdust, peat,
moss, or straw are suitable absorbents; sweep up and place in separate
Contain a large spillage by building a barrier of earth or sandbags.
Sweep up any spilled powder with damp sawdust; place in a separate
container for disposal.
Surplus product, spilled material, contaminated absorbents, containers,
etc., should be burnt in an incinerator designed for pesticide
disposal. When no incinerator is available, bury in an approved dump
or in an area where there is no risk of contamination of ground or
surface water. Comply with any local legislation applying to waste
5. HAZARDS FOR THE ENVIRONMENT AND
Amitrole has a high potential for leaching. In practice, adsorption on
most soils and rapid degradation prevent this mobility. Avoid
application to sandy soils with a low organic content, particularly on
slopes, and do not apply when rain is imminent.
The toxicity of the herbicide for terrestrial organisms is low and,
with recommended use, it should not present any hazard. Amitrole does
Use to control aquatic weeds will lead to concentrations sufficient to
kill some aquatic invertebrates, but not fish. These concentrations
may persist for several weeks.
6. SUMMARY OF CHEMICAL SAFETY
This summary should be easily available to all health workers concerned
with, and users of, amitrole. It should be displayed at, or near,
entrances to areas where there is potential exposure to amitrole, and
on processing equipment and containers. The summary should be
translated into the appropriate language(s). All persons potentially
exposed to the chemical should also have the instructions in the
swnmary clearly explained.
Space is available for insertion of the National Occupational Exposure
Limit, the address and telephone number of the National Poison Control
Centre, and local trade names.
SUMMARY OF CHEMICAL SAFETY INFORMATION
Chemical formulation: C2H4N4
CAS index name: 1 H-1,2,4-triazol-3-amine
CAS registry number: 61-82-5
RTECS registry number: XZ3850000
PHYSICAL PROPERTIES OTHER CHARACTERISTICS
Physical state crystalline solid Amitrole is a herbicide; it is formulated as a
Colour colourless solution or as a wettable powder
Relative molecular mass 84.08
Melting point (°C) 156.1
Vapour pressure (20 °C) 55 nPa
Solubility in water: at 25 °C 280 g/litre
at 53 °C 500 g/litre
ethanol (at 75 °C) 260 g/litre
n-hexane < 0.1 g/litre
dichloromethane 0.1-1 g/litre
2-propane 20-50 g/litre
toluene < 0.1 g/litre
Log Pow -0.97
HAZARD/SYMPTOMES PREVENTION AND PROTECTION FIRST AID
SKIN: Slight irritant; may Wear gloves when handling Wash off skin with water
cause sensitization concentrate
EYES: Slight irritant Avoid contact with eyes Flush eyes with water
INHALATION: Long-term exposure Avoid breathing spray-mist or dust
to spray-mist or dust may be harmful
INGESTION: No immediate hazard Wash hands before eating, drinking, Obtain medical attention,
expected, but long-term ingestion or smoking if ingested
may be harmful
ENVIRONMENT: Toxic for Do not contaminate vegetation,
vegetation ponds or waterways
SPILLAGE STORAGE FIRE/EXPLOSION
Absorb liquid spillage with earth or Store in locked storeroom, away from Some liquid formulations
sand; collect spilled powder with children and authorized personnel, may be flammable; use dry
damp sawdust; sweep up, place in and food and animal feed powder, carbon dioxide, or
closed and suitably labelled alcohol-resistant foams;
container, and dispose of safely; do cool nearby drums with
not contaminate personnel, water spray
vegetation, ponds, or waterways
WASTE DISPOSAL NATIONAL INFORMATION
Burn in high-temperature National Occupational Limit:
incinerator, with effluent gas
scrubbing; alternatively, bury in
an approved dump; comply with National Poison Control Centre:
Local trade names:
7. CURRENT REGULATIONS, GUIDELINES,
7.1 Previous Evaluations by International Bodies
Amitrole was evaluated by the Joint FAO/WHO Expert Committee on
Pesticide Residues (JMPR) in 1974 and 1977. In 1974, the JMPR
established a conditional acceptable daily intake (ADI) for man of
0.00003 mg/kg body weight, which was confirmed by the 1977 meeting;
however, this concept has been abandoned (WHO, 1990). Amitrole was
classified by IARC in Group 2B.
7.2 Exposure Limit Values
The American Conference of Governmental and Industrial Hygienists has
set a workplace threshold limit value (TLV) of 0.2 mg/m3 (time-weighted
average for an 8-h day).
No Codex maximum residue limits (MRLS) have been set for amitrole in
food. In 1987, the Codex Alimentarius Commission recommended that the
uses of amitrole should be restricted to those where residues in food
would not be expected to occur. The EEC has set MRLs at the limit of
determination (0.05 mg/kg).
7.3 Specific Restrictions
Amitrole has been officially approved for use as a herbicide in many
countries. In some countries, specific uses are defined, as well as
limitations and precautions.
7.4 Labelling, Packaging, and Transport
The European Community legislation requires labelling as a dangerous
substance, using the symbol shown on the next page.
The following standard risk phrases should be used:
R 22 Harmful if swallowed
R 40 Possible risk of irreversible effects
R 48 Danger of serious damage to health hy prolonged exposure
The following standard safety phrases should be used:
S 36 Wear suitable protective clothing
S 37 Wear suitable gloves.
7.5 Waste Disposal
No information available.
FAO/WHO (1975) 1974 Evaluations of some pesticide residues infood.
Rome, Food and Agriculture Organization of the United Nations, pp. 3-
FAO/WHO (1978) Pesticides residues infood: 1977 evaluations. Rome,
Food and Agriculture Organization of the United Nations, pp. 11-14.
IARC (1974) Amitrole. In: Some anti-thyroid and related substances,
nitrofurans and industrial chemicals. Lyon, International Agency for
Research on Cancer, pp. 31-43 (IARC Monographs on the evaluation of the
carcinogenic risk of chemicals to man. Vol- 7).
IARC (1986) Amitrole. In: Some halogenated hydrocarbons andpesticide
exposures. Lyon, International Agency for Research on Cancer, pp. 293-
317 (IARC Monographs on the evaluation of the carcinogenic risk of
chemicals to humans. Vol. 41).
WHO (1990) Environmental Health Criteria 104: Principles for the
toxicological assessment ofpesticide residues infood. Geneva, World
Health Organization, 82 pp.
WHO (1994) Environmental Health Criteria 158: Amitrole. Geneva, World
WORTHING C.R. & WALKER S.B. (1987) The pesticide manual 8th ed.
Lavenham, Lavenham Press Limited, British Crop Protection Council.