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    WORLD HEALTH ORGANIZATION             FOOD AND AGRICULTURE
                                          ORGANIZATION
    ORGANISATION MONDIALE DE LA SANTE     ORGANISATION POUR L'ALIMENTATION
                                          ET L'AGRICULTURE

  
                                          WHO/PCS/DS/94.72
                                          Original:  ENGLISH
                                          Distr.: LIMITED
                                          Date of issue:  February 1994


  WHO/FAO DATA SHEET ON PESTICIDES No. 72


  AZINPHOS-ETHYL

         It must be noted that the issue of a Data Sheet for a
    particular pesticide does not imply endorsement of the pesticide by
    WHO or FAO for any particular use, or exclude its use for other
    purposes not stated. While the information provided is believed to
    be accurate according to data available at the time when the sheet
    was compiled, neither WHO nor FAO are responsible for any errors or
    omissions, or any consequences therefrom.

    The issue of this document does    Ce document ne constitue pas une
    not constitute formal              publication. Il ne doit faire
    publication. It should not be      l'objet d'aucun compte rendu ou
    reviewed, abstracted or quoted     résumé ni d'aucune citation sans
    without the agreement of the       l'autorisation de l'Organisation
    Food and Agriculture               des Nations Unies pour
    Organization of the United         l'Alimentation et l'Agriculture
    Nations or of the World Health     ou de l'Organisation Mondiale de
    Organization.                      la Santé.


CLASSIFICATION:

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

1.0   GENERAL INFORMATION

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 
                                      phosphorodithioate 

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


      CAS registry number:          2642-71-9

      RTECS number:                 TD8400000

      Molecular formula:            C12H16N3O3PS2

      Relative molecular mass:      345.4

      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 hazardous. 

1.3   SELECTED PROPERTIES

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 hydrocarbons. 

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   AGRICULTURE, HORTICULTURE AND FORESTRY

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.

2.0   TOXICOLOGY AND RISKS

2.1   TOXICOLOGY - MAMMALS

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 mg/kg/diet. 

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 
      respectively. 

      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  TOXICITY TO NON-MAMMALIAN SPECIES

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.

3.0   FOR REGULATORY AUTHORITIES - RECOMMENDATIONS OF COMPOUND

3.1   RECOMMENDED RESTRICTIONS ON AVAILABILITY

      [For definition of categories see the 'Introduction to data sheets'].

      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 
      countries. 

3.2   TRANSPORTATION AND STORAGE

      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. 

3.4   DISPOSAL AND/OR DECONTAMINATION OF CONTAINERS

      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. 

3.5  SELECTION, TRAINING AND MEDICAL SUPERVISION OF WORKERS

      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. 

3.6   ADDITIONAL REGULATIONS RECOMMENDED IF DISTRIBUTED BY AIRCRAFT

      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   RESIDUES IN FOOD

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). 

4.0   PREVENTION OF POISONING IN MAN AND EMERGENCY AID

4.1   PRECAUTIONS IN USE

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 countries. 

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. 

4.2   ENTRY OF PERSONS INTO TREATED AREAS

      Unprotected persons should be kept out of treated crops for four 
      days.

4.3   SAFE DISPOSAL OF CONTAINERS AND SPILLAGE  

      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   EMERGENCY AID

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. 

5.0   FOR MEDICAL AND LABORATORY PERSONNEL

5.1   MEDICAL DIAGNOSIS AND TREATMENT IN CASES OF POISONING

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 reactivators. 

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

5.1.6  References to previously reported cases:  No 
      information available.

5.2   SURVEILLANCE TESTS

      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  LABORATORY METHODS

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
      poisoning. 

      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. 

                                       REFERENCES

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 Organization. 

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

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:
       Toxicological Abbreviations
       Azinphos-ethyl (WHO Pesticide Residues Series 3)
       Azinphos-ethyl (Pesticide residues in food: 1983 evaluations)