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    Original:  ENGLISH
    Distr.: LIMITED
    Date of issue:  February 1994

                                WHO/FAO DATA SHEET ON PESTICIDES

                                            No. 72


    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 

    The issue of this document does not constitute formal publication.  It 
    should not be reviewed, abstracted or quoted without the agreement of 
    the Food and Agriculture Organization of the United Nations or of the 
    World Health Organization. 

    Ce document ne constitue pas une publication.  Il ne doit faire l'objet 
    d'aucun compte rendu ou résumé ni d'aucune citation sans l'autorisation 
    de l'Organisation des Nations Unies pour l'Alimentation et 
    l'Agriculture ou de l'Organisation Mondiale de la Santé.                                                 


    Primary use:      Insecticide
    Secondary use:    Acaricide
    Chemical group:   Organophosphorus compound


    1.1   COMMON NAME:     azinphos-ethyl (ISO, BSI).

    1.1.1 Identity
          IUPAC chemical name:       S-(3,4-dihydro-4-oxobenzo[d]-[1,2,3]-
                                       triazin-3-ylmethyl) 0,0-diethyl 

          CAS name:                  O,O-diethyl S-[(4-oxo-1,2,3-
                                       benzotriazin-3(4 H )-yl)methyl]

          CAS registry number:       2642-71-9

          RTECS number:              TD8400000

          Molecular formula:         C12H16N3O3PS2

          Relative molecular mass:   345.4

          Structural formula:

          Structural formula

          Synonyms & tradenames: Athyl-GusathionR;  azinfosethyl;  
          AzinosR; Azinophos-aethylR;  Azinphos-etileR;  Bay 16255;  
          Bayer 16259; Benzotriazine derivative of ethyl dithiophosphate;
          Cotnion-ethylR; CrysthionR;  ENT 22,014;  Ethyl-azinophosR;  
          Ethyl-GusathionR; Ethyl-Guthion;  GusationR; GusathionR;  
          Guthion (ethyl);  R1513;  triazotion.

    1.2   SYNOPSIS:  Azinphos-ethyl is a broad spectrum,
          non-cumulative and non-systemic organophosphorus 
          insecticide/acaricide with good ovicidal properties and good 
          contact and stomach action.  It has excellent residual activity 
          and is not phytotoxic.  It is very toxic to mammals with a WHO 
          hazard classification of a technical product in class IB, Highly 


    1.3.1  Physical characteristics: Azinphos-ethyl forms 
          colourless (clear) crystals melting at 50 °C and boiling at 147 
          °C. It has a density of 1.284 and a refractive index of 1.5928.  
          The technical material is 92% pure compound. 

    1.3.2  Solubility:  The compound is virtually insoluble
          in water (4-5 mg per litre at 20 °C), it is soluble in most 
          organic solvents except light petroleum and aliphatic 

    1.3.3  Stability:  Azinphos-ethyl is thermally stable
          but is readily hydrolysed in alkaline media.

    1.3.4  Vapour pressure:  0.32 mPa at 20 °C.


    1.4.1  Common formulations:  These include emulsifiable 
          concentrates, 200 - 400 g a.i./L; wettable powders, 250-400 g 
          a.i./kg;  and, an ULV product, 500 g a.i./L. 

    1.4.2  Pests controlled:  These include susceptible
          spider mites, aphids, caterpillars, potato bug, beetles, 
          bollweevils, whiteflies, bollworms, thrips and other biting and 
          sucking insects. 

    1.4.3  Use pattern:  Azinphos-ethyl is no longer 
          registered for use in many countries, but it is still widely used 
          in some countries, especially on fruit and vegetable crops, 
          cotton, pastures, coffee, cereals, potatoes, hops, grapes, 
          citrus, rice, tobacco and other crops. 

    1.4.4  Unintended effects:  Considered to be non-
          phytotoxic when used as recommended.  

    1.5   PUBLIC HEALTH USE - No recommended use.

    1.6   HOUSEHOLD USE:  No recommended use.



    2.1.1  Absorption route:  Azinphos-ethyl is absorbed from 
          the gastrointestinal tract, through the intact skin, and by 
          inhalation of fine spray mist and dusts.   

    2.1.2  Mode of action:  Azinphos-ethyl after conversion
          to the oxygen analogue is an inhibitor of acetylcholinesterase 
          thereby causing impairment of nervous transmission. 

    2.1.3  Excretion products:  After oral administration 
          azinphos-ethyl was almost completely absorbed from the 
          gastrointestinal tract of the rat.  Following intravenous or oral 
          administration of 0.1 - 6 mg/kg b.w. to rats, 60 - 65% of the 
          compound was eliminated in urine and 20 - 40% was excreted in 
          faeces irrespective of route of administration or dose level.  
          Less than 0.1% of the compound when dosed intravenously or orally 
          at 2 mg/kg, was eliminated with the exhaled air within 24 hours. 

    2.1.4  Toxicity, single dose (technical product):

          Oral LD50
          Rat               12 mg/kg b.w.
          Rat (F)          7.2 mg/kg b.w.
          Rat (M)         15.2 mg/kg b.w.
          Guinea-pig      17.0 mg/kg b.w.

           Dermal LD50
           Rat           72-280 mg/kg b.w.
           Rat (M)          545 mg/kg b.w. (24 hour exp.)
           Rat (F)          402 mg/kb b.w. (24 hour exp.)

          Intraperitoneal LD50
          Rat (M)      7.5-9.2 mg/kg b.w.
          Rat (F)          4.4 mg/kg b.w.
          Mouse        3.8-4.0 mg/kg b.w.

          Inhalation LC50
          Rat          c0.15 mg/L (4 hours exposure)

    2.1.5  Toxicity, repeated dose:

          Oral:  Male rats given 1.0 mg/kg b.w. orally for 28 consecutive
          days showed no clinical signs of toxicity and no changes in body 
          weight gain.  Cholinesterase activity was depressed in 
          erythrocytes by 50% after 2 days, 82% by three days and 90% by 28 
          days.  Normal cholinesterase activity was re-established by 35 
          days after administration ceased. 
          Dermal:  Male and female rabbits were treated for three weeks with
          15 x 7 hour applications of 0.1 - 0.05 mg/kg b.w.  The no-effect-
          level (NOEL) was 0.05 mg/kg b.w. 

          Inhalation:  Male and female rats were exposed 15 times for 6 hours
          to 0, 0.3, 1.8 or 12.7 mg/m3 air over a three week period.  The 
          NOEL was 0.3 mg/m3 air. 

          Cumulation of compound:  Groups of female rats were administered
          doses of 0.5, 1, 2, or 3 mg/kg b.w. intraperitoneally for 60 
          days.  Only the two highest dosage levels caused a reduction in 
          weight gain and an increased mortality.  Azinphos-ethyl does not 
          accumulate in body tissues, but a cumulation of effect was 
          demonstrated at higher doses. 

    2.1.6  Dietary studies:

          Short term:  Groups of 15 male and female rats were fed azinphos-
          ethyl at 0, 1, 2, 4 and 8 mg/kg/diet for 90 days.  There were no 
          clinical signs of toxicity, no changes in blood chemistry and no 
          increases in mortality in any of the treatment groups.  After 30 
          days the erythrocyte cholinesterase activity was depressed in 
          rats fed on a diet containing 4 mg/kg azinphos-ethyl.  In a group 
          of rats fed 8 mg/kg plasma cholinesterase activity was depressed 
          and stabilized after one week, while the erythrocyte 
          cholinesterase activity continued to fall for the first 30 days.  
          Females were more sensitive than males.  There were no treatment 
          related gross or histological abnormalities found in the organs 
          or tissues of the treated animals.  2 mg/kg of diet was accepted 
          as the no-effect level. 

          In another experiment, groups of 12 male and female rats were fed 
          diets containing 0, 5, 10 or 50 mg of azinphos-ethyl/kg/diet for 
          16 weeks.  At 50 mg/kg/diet males showed a decrease in body 
          weight but no clinical signs of toxicity.  In this group 
          cholinesterase activity was depressed in erythrocytes, serum and 
          brain.  At 10 mg/kg/diet only serum and erythrocyte 
          cholinesterase activities were inhibited.  Rats on the 5 
          mg/kg/diet showed only erythrocyte cholinesterase activity 
          depression. No gross or histological abnormalities were observed 
          in any of the treatment group animals. 

          In a 12 week study, groups of two male and female young dogs were 
          fed 0, 0.25, 0.5, 1, 2, 3 and 10 mg of azinphos-ethyl/kg/diet.  
          At dietary levels of 3 and 10 mg/kg the dogs exhibited clinical 
          signs of poisoning after 6 and 1 weeks respectively.  They were 
          removed from these diets and their cholinesterase activity 
          returned to normal after 3-4 weeks on normal diet.  
          Cholinesterase activities were depressed in all other treatment 
          groups, but they returned to normal in treated animals after 2-3 
          weeks on normal diet.  Only in the group receiving 0.25 mg/kg of 
          diet did the erythrocyte activity remain unchanged, and this was 
          accepted as the no-effect-level. 

          Long term:  Male and female Rhesus monkeys were dosed orally with
          azinphos-ethyl at 0, 0.02, 0.04 and 0.08 mg/kg b.w./day for 32 
          months.  A NOEL of 0.02 mg/kg b.w. was obtained.  At higher doses 
          depression of plasma cholinesterase activity was observed. 

          In a two-year feeding study male and female dogs were fed 
          azinphos-ethyl at 0, 0.1, 0.2, 2, 20, 30, 60 and 90 mg/kg/diet.  
          A NOEL of 0.1 - 0.2 mg/kg/diet was obtained.  At doses up to 30 
          mg/kg/diet only depression of cholinesterase activity in plasma 
          and erythrocytes was observed. 

          In a two year feeding study in male and female rats, azinphos-
          ethyl was fed at 0, 2, 8 and 32 mg/kg/diet.  No carcinogenic 
          effects were observed up to and including 32 mg/kg/diet. 

          In a two year feeding study in male and female mice, azinphos-
          ethyl was fed at 0, 0.5, 1.4, 4.0 and 11.3 mg/kg/diet.  No 
          carcinogenic effects were observed up to and including 11.3 

    2.1.7  Supplementary studies of toxicity:

          Carcinogenicity:  In long term studies in mice and rats
          carcinogenicity was not demonstrated at 11.3 and 32 mg/kg/diet 

          Teratogenicity:  Studies in rats and rabbits did not show any
          embryotoxic or teratogenic effects.

          Mutagenicity:  Azinphos-ethyl was not mutagenic in the
          Salmonella/Microsome Test (Ames-test), micronucleus-test nor in 
          the dominant-lethal test.  It has no DNA-damaging properties. 
          Neurotoxicity:  No ataxia was observed in hens five weeks after a
          single administration of 10 or 25 mg/kg b.w. given orally.  There 
          were no clinical or histological signs in hens fed 75, 150, 300 
          or 600 mg/kg/diet for 30 days during the treatment period or at 4 
          weeks after cessation of treatment. 

    2.1.8  Modification of toxicity:  No potentiation 
          occurred when azinphos-ethyl was used with a variety of 
          pesticides including parathion, methyl parathion, malathion, 
          trithion, phosdrin, carbaryl, diazinon, azinphos-methyl, 
          coumaphos, chlorobenzilate or fenchlorphos.  A twofold 
          potentiation occurred when used with ethion. 

    2.2   TOXICOLOGY - MAN

    2.2.1  Absorption route:  Azinphos-ethyl may be absorbed 
          from the gastrointestinal tract, through the intact skin, and by 
          inhalation of fine spray mist and dusts. 

    2.2.2  Dangerous doses:  No information available.

    2.2.3  Observations on occupationally exposed workers: 
          No information available.

    2.2.4  Observations on exposure of the general population: 
          No information available.

    2.2.5  Observations on volunteers:  Six volunteers 
          received 0.01 or 0.02 mg azinphos-ethyl technical product per day 
          in gelatine capsules for 28 consecutive days.  The volunteers 
          tolerated the treatment without any effect. 

    2.2.6  Reported mishaps:  None.


    2.3.1  Fish:  
          LC50 (96 h)
                 Goldfish         0.1 mg/L
                 Guppies   0.01 - 0.1 mg/L

    2.3.2  Birds:
          Oral LD50     Chicks       34 mg/kg b.w.
          Oral LD50     Quail (F)    20 mg/kg b.w.

    2.3.3  Other species:  Toxic to bees.



          [For definition of categories see the 'Introduction to Data 

          Liquid formulation of 6.0% and over, Category 2

          Other liquid formulations, Category 3

          Solid formulations of 25% and over, Category 2

          Other solid formulations, Category 3

          Azinphos ethyl has been banned or severely restricted in several 


          All formulations:  Should be transported in clearly labelled 
          impermeable containers and stored under lock and key, secure from 
          access by unauthorized persons and children.  No food or drink 
          should be stored in the same compartment. 

    3.3   HANDLING
          All formulations:  Full protective clothing (see 4.3 part 4) 
          should be used by those handling the compound.  Adequate washing 
          facilities should be available at all times during handling and 
          should be close to the site of handling.  Eating, drinking and 
          smoking should be prohibited during handling and before washing 
          after handling. 


          All formulations:  Whenever possible containers should be 
          either returned to the supplier, or safely disposed of in an 
          approved manner.  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. 


          All formulations:  Pre-employment and periodic medical 
          examination of workers is necessary and should include blood 
          cholinesterase activity tests.  Special account should be taken 
          of the workers' ability to comprehend and follow instructions.  
          Training of workers in techniques to avoid contact essential. 


          All formulations:  Pilots and loaders should have special 
          training in application methods and early symptoms of poisoning, 
          and must wear a suitable respirator.  Use of flagmen not 
          recommended. Flagmen, if used, should wear protective clothing 
          and be located well away from the dropping zone. 

    3.7   LABELLING
                                  DANGER - POISON
                          (Skull and cross bones insignia)

          Azinphos-ethyl is an organophosphorus compound which inhibits 
          cholinesterase enzymes.  It is of very high toxicity.  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.  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 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 sulphate is a pharmacological antidote. 
          Artificial respiration may be needed. 


    3.8.1  Maximum residue levels:  The Joint FAO/WHO Meeting on 
          Pesticide Residues has not recommended maximum residue levels 
          neither has it established an Acceptable Daily Intake (ADI). 



    4.1.1  General:  Azinphos-ethyl is an organophosphorus 
          pesticide of high toxicity.  It is readily absorbed through the 
          intact skin, from the gastrointestinal tract and by inhalation.  
          Repeated exposure may have a cumulative effect on cholinesterase 
          activity.   Most formulations should be handled by trained 
          personnel only.  Its use is severely restricted in several 

    4.1.2  Manufacture and formulation:  Closed systems and
          forced ventilation may be required to reduce as much as possible 
          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, neoprene gloves and respirator 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 face mask should be worn, as well as an 
          impermeable hood, clothing, boots, and neoprene 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 other exposed skin should be washed.  

    4.1.4  Other associated workers:  Persons exposed to 
          the compound 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: 
          Subject to 4.2 below, persons other than applicators are not 
          likely to be exposed to hazardous amounts of azinphos-ethyl. 


          Unprotected persons should be kept out of treated crops for four 


          Residues in containers should be kept to a minimum and emptied in 
          a diluted form into a deep dry pit (depth over 0.5 m), taking 
          care to avoid contamination of ground waters.  The empty 
          containers should be disposed of in an approved manner.  If not 
          returned to the producer, re-use of containers should not be 
          permitted for any purpose. 

          Spillage of liquid azinphos-ethyl formulations should be 
          contained with absorbent material.  This material or spillage of 
          dry residues should be collected and burned or buried as 
          described above. Residues should be removed by scrubbing with 
          detergent and then rinsing with large quantities of water. 

          Impermeable gauntlets and protective overalls should be used for 
          all handling procedures. 


    4.4.1  Early symptoms of poisoning:  Early symptoms of 
          poisoning may include excessive sweating, headache, weakness, 
          giddiness, nausea, vomiting, increased salivation, stomach pains, 
          diarrhoea, blurred vision, slurred speech and muscle twitching. 
          Later there may be shortness of breath, convulsions and coma. 

    4.4.2  Treatment before person is seen by physician, if 
    these symptoms appear following exposure: 
          The person should stop work immediately, remove contaminated 
          clothing and wash contaminated skin with soap and water and flush 
          the area with large quantities of water.  If swallowed, and if 
          the person is conscious, vomiting should be induced.  Artificial 
          respiration should be given when necessary bearing in mind that 
          if mouth-to-mouth resuscitation is used, vomit may contain toxic 
          amounts of pesticide.  Call a physician immediately or organize 
          immediate transport to a physician or hospital. 



    5.1.1  General information:  Azinphos-ethyl is an 
          organophosphorus pesticide of high mammalian toxicity. It is 
          readily absorbed from the gastrointestinal tract, through the 
          intact skin and by inhalation.  It is converted  in vivo to the 
          oxygen analogue which inhibits cholinesterases.  It does not 
          accumulate in body tissues. 

    5.1.2  Symptoms and signs:  Poisoning is due to 
          excessive stimulation by acetylcholine of all cholinergic 
          innervation.  Thus initial symptoms and signs of poisoning may 
          include excessive sweating and salivation, headache, weakness, 
          miosis, dyspnoea, nausea, vomiting and diarrhoea, blurred vision 
          and muscle fasciculations.  More severe poisoning leads to 
          respiratory failure due to a combination of bronchorrhea, 
          bronchoconstriction (muscarinic effects), paralysis of 
          respiratory muscles (nicotinic effects) and respiratory centre 
          paralysis (central effects).  The latter include, in severe 
          cases, coma and convulsions. 

    5.1.3  Laboratory:  Diagnosis is confirmed by finding 
          inhibition of erythrocyte or whole blood acetylcholinesterase. 
          However, treatment must start immediately and cannot be delayed 
          until confirmation from the laboratory.  This test cannot be used 
          to control the effectiveness of the treatment nor is it of help 
          for prognosis. 

    5.1.4  Treatment:  Patients with respiratory failure 
          must be given artificial ventilation, then diazepam (10 mg 
          intravenously) to control convulsions.  When vital functions are 
          controlled, atropine sulfate is given (initial dose is usually 2 
          mg intravenously) followed by pralidoxime (1000 mg) or toxogonin 
          (250 mg) by slow intravenous infusion. 

          If the pesticide has been ingested, gastric lavage might be 
          needed or vomiting induced.  Protection of airways (intubation) 
          is required if inducing vomiting in unconscious patients. 

          For skin contact, the skin should be washed with soap and large 
          amounts of water.  Precautions should be taken by medical 
          personnel during these decontamination procedures to prevent 
          their own overexposure.  If the compound has entered the eyes, 
          they should be washed with large quantities of saline or water. 

          Atropine treatment might be required for several days after 
          poisoning.  Only clinical assessment determines atropine dose, 
          i.e. evident signs of atropinization (dry mouth, tachycardia, 
          vasodilation, mydriasis) should be maintained.  Total amounts of 
          atropine given to these patients might be extremely high because 
          they are tolerant to the effects of atropine. 

          Caution should be taken when doses of atropine are reduced 
          because reappearance of symptoms might occur, due to 
          redistribution processes in the body.  Cholinesterase 
          reactivators such as pralidoxime and toxogonin are usually only 
          effective during the first few days of poisoning, unless the slow 
          disposal of the chemical within the body suggests that some 
          acetylcholinesterase is newly inhibited.  Indications for the 
          continuing use of reactivators might derive from measurements of 
          erythrocyte cholinesterase before and after treatment with such 

    5.1.5  Prognosis:  Unless brain hypoxia has occurred,
          full recovery is expected. 

    5.1.6  References to previously reported cases:  No 
          information available.


          Any fall in erythrocyte cholinesterase activity to 70% of the 
          pre-exposure values, requires an investigation of working methods 
          and hygiene and more frequent cholinesterase tests.  Symptoms of 
          poisoning may appear when the erythrocyte cholinesterase activity 
          is less than 35% of normal. If erythrocyte cholinesterase 
          activity is less than 50% of normal, the worker must be suspended 
          from all contact with organophosphorus or carbamate pesticides 
          until the level rises above 70% of pre-exposure value.  
          Pseudocholinesterase activity in the plasma can fall to very low 
          levels without evidence of symptoms.  This only indicates 
          undesirable exposure. 


    5.3.1  Detection and assay of compound:

          Analysis of the product is by colorimetric measurement of the 
          complex of the liberated O,O-diethylphosphorodithioate (following 
          alkaline hydrolysis) and copper (II) ions, extracted and measured 
          at 420 nm. Residues are measured by GLC.  The following are some 
          basic references: 

          CIPAC Handbook, 1070, 1, 18.

          Curini M et al (1980), Talanta 27(1): p. 45.

          Ferreira JR, & Fernandes A (1980), J Assoc Off Anal Chem 63(3):
          p. 517.

          Meagher WR et al (1960), J Agric Food Chem 8: p. 282.

          Mestres R et al (1977), Anal Falsif Expert Chim, 70(751): p. 177.

          Miles JRW (1964), J Assoc Off Agric Chem, 47: p. 882.

          Stan HJ et al (1977), Fresentius Z Anal Chem,  287 (4-5): p. 271.

          Stein UB & Pitman KA (1976), J Assoc Off Anal Chem 59(5): 
          p. 1094.

    5.3.2  Other tests in case of poisoning:  Activity of 
          cholinesterase in the blood provide the most useful diagnosis of 

          Ellman GL et al (1961), A new and rapid colorimetric 
          determination of acetylcholinesterase activity, Biochem pharmacol 
          7: 88-95.

          Wilhelm K & Reiner E (1973), Bull Wld Health Org, 48: 235-238.

          Urine metabolites such as dialkylphosphates and 
          dialkylthiophosphates may also be determined in order to give an 
          indication of exposure, particularly when exposure is so low as 
          not to inhibit cholinesterase.  For methods see section 5.3.1, 
          Detection and Assay. 

    1.    The Pesticide Manual, A World Compendium (9th edition 1991), 
          Worthing CR & Hance RJ, eds., British Crop Protection Council, 20 
          Bridport Road, Thornton Heath, CR4 7QG, United Kingdom. 

    2.    WHO (1974) 1973 Evaluations of some pesticide residues in food.  
          WHO Pesticide Residues Series, No. 3, Geneva, World Health 

    3.    WHO (1986), Environmental Health Criteria 63;  Organophosphorus 
          Insecticides.  A General Introduction;  Geneva, World Health 

    4.    WHO (1994) The WHO Recommended Classification of Pesticides by 
          Hazard and Guidelines to Classification 1994-1995, Geneva, World 
          Health Organization mimeographed document (WHO/PCS/94.2). 

                                         = = = 

See Also:
        Azinphos ethyl (PIM 054)