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)



    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) 
          ISSN 0259-7268

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                          World Health Organization 1994

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    1. PRODUCT IDENTITY AND USES...............................

          1.1 Identity.........................................

          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    
              analytical methods...............................

          2.2 Sources of human and environmental exposure......

          2.3 Environmental transport, distribution,    
              and transformation...............................

          2.4 Environmental levels and human exposure..........

          2.5 Kinetics and metabolism in laboratory animals    
              and humans.......................................

          2.6 Effects on experimental animals and in vitro    
              test sysytems....................................

          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.........................

          3.1 Conclusions......................................

          3.2 Recommendations for the protection of human health      
              and the environment..............................

       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.......................

          4.3 Storage..........................................

          4.4 Transport........................................

          4.5 Spillage.........................................

          4.6 Disposal.........................................




          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: 

                                The Director
                 International Programme on Chemical Safety
                         World Health Organization
                               1211 Geneva 27

                       THE INFORMATION IN THIS GUIDE
                         SHOULD BE CONSIDERED AS A             
                        HEALTH AND SAFETY PROGRAMME


                            1. PRODUCT IDENTITY AND USES

    1.1 Identity

          Common name:  amitrole

          Chemical structure:       

Figure 1;;;grph85_1.bmp

    Molecular formula:     C2H4N4

    Common synonyms:       aminotriazole; 2-aminotriazole; 3-aminotriazole;
                           3-amino-S-triazole; 3-amino-1,2,4-triazole;     
                           3-amino-lH-1,2,4-triazole; AT; 3AT; ATA;        
                           3,A-T; ATZ; AT-90; triazolamine;                
                           1,2,4-triazol-3-amine; 5-amino-IH-1,2,4-triazole
    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)
    names:                 3-amino-S-triazole(8CI)

    IUPAC names:           1H-1,2,4-triazol-3-ylamine

    CAS registry
    number:                61-82-5

    RTECS registry
    number:                XZ3850000

    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 
    one plant. 

    The use of amitrole in waterways and watersheds has led to transitory 
    water concentrations of up to 150 g/litre.  Concentrations in running 
    water fall rapidly to nondetectable levels (< 2 g/litre) within 2 h.  
    Application to ponds gave an initial water concentration of 1.3 
    mg/litre, falling to 80 g/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 
    epidemiological studies. 

    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

    3.1 Conclusions

    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 
    application stages. 

    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 
    of determination). 

                    4. HUMAN HEALTH HAZARDS, PREVENTION 

    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 
    with thiocyanate. 

    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. 

    4.3 Storage

    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. 

    4.4 Transport

    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 
    and undamaged. 

    4.5 Spillage

    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. 

    4.6 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 
                              THEIR PREVENTION

    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 
    not bioaccumulate. 

    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. 



                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
    Solubility in
          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

    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 regulations

                                         Local trade names:
                      7. CURRENT REGULATIONS, GUIDELINES,
                                 AND STANDARDS
    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

Figure 2;;;grph85_2.bmp

    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 
    Health Organization. 

    WORTHING C.R. & WALKER S.B. (1987) The pesticide manual 8th ed. 
    Lavenham, Lavenham Press Limited, British Crop Protection Council. 


    See Also:
       Toxicological Abbreviations
       Amitrole (EHC 158, 1994)
       Amitrole (ICSC)
       Amitrole (WHO Pesticide Residues Series 4)
       Amitrole (Pesticide residues in food: 1977 evaluations)
       Amitrole (Pesticide residues in food: 1993 evaluations Part II Toxicology)
       Amitrole (Pesticide residues in food: 1997 evaluations Part II Toxicological & Environmental)
       Amitrole  (IARC Summary & Evaluation, Supplement7, 1987)
       Amitrole  (IARC Summary & Evaluation, Volume 7, 1974)
       Amitrole  (IARC Summary & Evaluation, Volume 41, 1986)
       Amitrole  (IARC Summary & Evaluation, Volume 79, 2001)