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    WORLD HEALTH ORGANIZATION
    ORGANISATION MONDIALE DE LA SANTE
    
    
    FOOD AND AGRICULTURE ORGANIZATION
      OF THE UNITED NATIONS
    ORGANISATION DES NATIONS UNIES POUR
      L'ALIMENTATION ET L'AGRICULTURE
    
    
    WHO/PCS/DS/94.92
    Original:  ENGLISH
    Distr.: LIMITED
    Date of issue:  February 1994
    
    
    
    
    
    
    
                            WHO/FAO DATA SHEET ON PESTICIDES
    
    
                                          No. 92
    
    
                                        FENAMIPHOS
    
    
    
    
    
    
    

    
    
    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 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.                                                 
    

    
    CLASSIFICATION:
    
    Primary use:      Nematicide
    Secondary use:    Insecticide
    Chemical group:   Organophosphorus compound
    
    1.0   GENERAL INFORMATION
    
    1.1   COMMON NAME:   fenamiphos (E-ISO);  phénamiphos (F-ISO)
    
    1.1.1  Identity:
    
          IUPAC name:               ethyl 4-methylthio-m-tolyl
                                      isopropylphosphoramidate
    
          CAS name:                 ethyl 3-methyl-4-(methylthio)phenyl (1-
                                      methylethyl)phosphoramidate
    
          CAS registry number:      22224-92-6
    
          RTECS number:             TB3675000
    
          Molecular formula:        C13H22NO3PS
    
          Relative molecular mass:  303.4
    
          Structural formula:
    
          Structural formula;p92.bmp
    
    
    
    
          Synonyms or trade names: Bay 68138;  NemacurR;  Nemacur PR.
    
    1.2   SYNOPSIS:  Fenamiphos, an organophosphorus 
          nematicide, is extremely toxic to mammals.  The technical product 
          is listed in the WHO Recommended Classification of Pesticides by 
          Hazard under class Ia, Extremely hazardous.  Readily absorbed 
          through foliage and roots of plants, it has a fairly long-acting 
          systemic activity in plants.  Residues are generally moderately 
          well adsorbed on soil, reducing the amount of leaching through 
          soil into ground waters.  No indications of toxicity other than 
          through inhibition of acetylcholinesterase activity are reported 
          in the limited amount of published data available. 
    
    1.3   SELECTED PROPERTIES
    
    1.3.1  Physical characteristics:  The technical product is 
          a tan, waxy solid with a melting point around 46 °C.  Pure 
          fenamiphos is a white crystalline product with a melting point of 
          49.3 °C.  The technical material has a minimum purity of 87%.  
          Fenamiphos is not corrosive. 
    
    1.3.2  Solubility:  In water at 20 °C, 700 mg/L. 
          Slightly soluble in most organic solvents. 
    
    1.3.3  Stability:  Hydrolysed by strong acids and
          alkalis.  No degradation in propanol/water (1:1) at 40 °C, pH 7, 
          after 50 days. 
    
    1.3.4  Vapour pressure:  0.12 mPa (20 °C)
    
    1.4   AGRICULTURE, HORTICULTURE AND FORESTRY
    
    1.4.1  Common formulations:  Granular 5-15%, emulsifiable 
          concentrate 40%, 250 g/L EW.  In combination with carbofuran, 
          disulfuron, isofenphos or fensulfothion in granule and 
          emulsifiable concentrate formulations. 
    
    1.4.2  Susceptible pests:  Effective against ecto- 
          and endo-parasitic, free-living, cyst-forming and root-knot 
          nematodes.  May also control mites, aphids, thrips, fleahoppers 
          and mealy bugs. 
    
    1.4.3  Use pattern:  Used as a soil treatment, with 
          or without incorporation, as a root dip, as a seed treatment or 
          as a foliar application.  Fenamiphos is readily absorbed through 
          roots and leaves to give a systemic nematicidal action.  Controls 
          nematodes in a wide variety of field, vegetable and fruit crops;  
          good water solubility makes it particularly useful in wet or 
          heavy soils. 
    
    1.4.4  Unintended effects:  Toxic to fish.  Some 
          phytotoxicity has been reported following foliage application to 
          alfalfa, squash, tomatoes, and some ornamentals. 
    
    1.5   PUBLIC HEALTH USE:  
          No recommended usage reported.
    
    1.6   HOUSEHOLD USE:  No recommended usage reported.
    
    2.0   TOXICOLOGY AND RISKS
    
    2.1   TOXICOLOGY - MAMMALS
    
    2.1.1  Absorption route:  Femamiphos may be absorbed from
          the gastrointestinal tract; by inhalation or through intact skin. 
    
    2.1.2  Mode of action:  Direct inhibition of
          cholinesterases.  The sulfoxide and sulfone metabolites are more
          potent inhibitors than fenamiphos itself. 
    
    2.1.3  Excretion products:  Fenamiphos is extensively
          metabolized by the rat to sulfoxides and sulfones, N and O 
          dealkylation products and conjugates.  Excretion of a 2 mg/kg 
          b.w. radio-labelled oral dose was predominantly via the urine and 
          expired air and was essentially complete within 15 hours. 
    
    2.1.4  Toxicity, single dose:
        Oral LD50
          Rat (M & F)     2.3 - 19.4 mg/kg b.w. 
          Mouse (M)             22.7 mg/kg b.w.
          Mouse (F)              8.3 mg/kg b.w. 
          Rabbit                 5.0 mg/kg b.w. 
          Rabbit (M)       10 - 17.5 mg/kg b.w.
          Guinea pig (M)    56 - 100 mg/kg b.w.
          Dog (M)             ca. 10 mg/kg b.w.
          Cat (M)             ca. 10 mg/kg b.w.
    
        Dermal LD50                        
          Rat (M)           73 - 500 mg/kg b.w.
          Rat (F)           84 - 154 mg/kg b.w.
          Rabbit           178 - 225 mg/kg b.w.
    
        Inhalation LC50            
          1 hour     Rat   110 - 175 mg/m3
          4 hour     Rat    91 - 100 mg/m3
    
        Intraperitoneal LD50
          Rat (M & F)      3.0 - 4.9 mg/kg b.w.
          Mouse (M & F)          3.4 mg/kg b.w.
          Guinea pig (M)         17.3 mg/kg b.w.
    
          Primary irritation:  Application of 0.25 ml of a liquid 
          formulation (equivalent to 0.085 mg a.i.) to intact or abraded 
          rabbit skin did not cause primary irritation.  Instillation of
          the same formulation into the conjunctival sac of rabbits caused 
          irritation at 0.034 mg a.i. equivalent. 
    
    2.1.5  Toxicity, repeated dose:  Oral or 
          intraperitoneal administration of 1.7 or 1.5 mg/kg b.w./day 
          respectively, five days/week for sixty days, was not lethal to 
          male rats, and no evidence of cumulative toxicological effects 
          was observed.  Female rats survived daily intraperitoneal 
          administration of 1 mg/kg for sixty days while 40% of those 
          administered 2 mg/kg did not survive.  All rats died at 3 mg/kg. 
    
          No effects on growth, haematology, clinical chemistry, gross or 
          microscopic pathology were observed in rats exposed to aerosol 
          concentrations of up to 3.5 mg/m3 for three weeks.  Plasma
          cholinesterase activity was depressed at 3.5 mg/m3 but no 
          effect was observed on erythrocyte and brain cholinesterase. 
    
          Dermal application 0.5, 2.5 or 10 mg/kg b.w. to rabbits for three 
          weeks caused no adverse effects other than a slightly decreased 
          plasma cholinesterase activity at 2.5 mg/kg b.w. and above. 
    
          Cumulation of effect:  Fenamiphos does not accumulate in body 
          tissues but cumulation of effects was demonstrated during 
          exposure. Plasma and erythrocyte cholinesterase activity remain 
          inhibited but clinical symptoms such as behavioural changes and 
          tremors appear only during the early period of exposure. 
    
    2.1.6  Dietary studies:
    
          Short term:  Administration of 0, 4, 8, 16 or 32 mg/kg/diet to 
          rats for three months caused a slight increase in absolute liver 
          weights in males at the two highest concentrations.  Relative 
          liver weights were unaltered, however, and no abnormal 
          histopathology of this, or any other organ, was observed. 
          Evidence of cholinergic stimulation was apparent in both sexes at 
          32 mg/kg/diet but was only observed for the first two months of 
          the study.  Plasma cholinesterase activity was depressed at 8 
          mg/kg/diet and above.  A no-effect-level (NOEL) based upon plasma 
          cholinesterase was found to be 4 mg/kg/diet. 
    
          Groups of beagle dogs were fed fenamiphos in the diet at 0, 2, 6 
          and 18 mg/kg/diet for three months.  Administration of 18 
          mg/kg/diet to male and female dogs caused behavioral 
          abnormalities, evidenced by signs of cholinergic stimulation and 
          a decreased growth rate in the females.  At 2 mg/kg/diet plasma 
          cholinesterase activity was marginally decreased in both sexes 
          while erythrocyte cholinesterase activity was unaffected at this 
          dose.  The NOEL for dogs was considered to be 2 mg/kg/diet. 
    
          In a two year feeding study in dogs at concentrations of 0, 0.5, 
          1.0, 2.0, 5.0 and 10.0 mg/kg/diet no adverse effects other than 
          inhibition of blood cholinesterase were observed.  The NOEL for 
          plasma cholinesterase was 1 mg/kg/diet. 
    
          Long term:  Signs of cholinergic stimulation were observed in 
          Wistar rats receiving 30 mg/kg/diet (maximum dose tested) but 
          were apparent only for the first six weeks of the two year study. 
          Inhibition of plasma cholinesterase was observed at 
          concentrations above 3 mg/kg/diet.  Increased absolute and 
          relative thyroid weights were observed in females receiving 30 
          mg/kg/diet, but goitre, tumours or other abnormal 
          histopathological findings were absent.  No adverse effects were 
          observed on growth, mortality, haematologic or clinical chemistry 
          evaluations, or in histopathologic examinations.  A NOEL was set 
          at 3 mg/kg/diet (equivalent to 0.17, to 0.23 mg/kg b.w./day) on 
          the basis of plasma cholinesterase inhibition. 
    
          Groups of male and female Fischer 344 rats were fed diet 
          containing mean effective concentrations of 0, 1.7, 7.8 and 37 
          mg/kg/diet (equivalent to 0, 0.1, 0.5 and 2.5 to 3.4 mg/kg 
          b.w./day) of technical fenamiphos (89.3% pure) for two years.  
          Erythrocyte cholinesterase activity was significantly inhibited 
          in both sexes at all dose levels (approximately 6%, 30% and 70% 
          at 1.7, 7.8 and 37 mg/kg/diet respectively).  Brain 
          cholinesterase activity was also significantly decreased in high 
          dose males at termination and in both sexes after one year of 
          treatment only.  No treatment-related neoplastic lesions were 
          observed. 
    
    2.1.7  Supplementary studies of toxicity:
    
          Carcinogenicity:  No evidence of carcinogenicity was observed in 
          two two-year chronic/carcinogenicity studies in rats (see Long 
          term above) or in mice fed fenamiphos for 18 months at 25 and 50 
          mg/kg/diet. 
    
          Teratogenicity:
      
          Rats:  Pregnant female FB30 rats were orally administered 
          (gavage) fenamiphos (92.5%) at doses of 0, 0.3, 1.0 and 3.0 mg/kg 
          b.w. day from day 6 to day 15 of gestation. 
    
          Cholinergic signs were observed in 18 out of 25 dams receiving 3 
          mg/kg b.w./day.  No signs of toxicity were observed at 0.3 and 
          1.0 mg/kg b.w./day. 
    
          It was concluded that fenamiphos at doses up to and including 3.0 
          mg/kg b.w./day was not embryotoxic or teratogenic in FB30 rats. 
    
          Rabbits:  Pregnant female Chinchilla rabbits were orally 
          administered (gavage) fenamiphos (91% pure) at doses of 0, 0.1, 
          0.5 and 2.5 mg/kg b.w./day from day 6 through day 18 post coitum. 
    
          Maternal toxicity including death was observed at 5 mg/kg 
          b.w./day. 
    

    
          Based on the maternal toxicity observed at the high dose level, 
          the NOEL for the females was 0.5 mg/kg b.w./day.  Fenamiphos was 
          not considered to be embryotoxic or teratogenic to Chinchilla 
          rabbits. 
      
          Reproduction:  No adverse effects on reproduction were observed 
          in a three-generation study in rats receiving fenamiphos at 0, 3, 
          10 and 30 mg/kg of diet. 
    
          Mutagenicity:  Fenamiphos showed no mutagenic activity in a 
          micronucleus test, in the Ames test and in  Escherichia coli .  
          In a dominant lethal test in mice, fenamiphos did not induce 
          alterations in male germinal cells. 
    
          Neurotoxicity: No evidence of delayed neurotoxicity was observed 
          in hens following a single gavage dose of 5.0 mg/kg b.w. (LD50) 
          or thirty days dietary administration of 1, 3, 10 or 30 
          mg/kg/diet. 
    
    2.1.8  Modification of toxicity:  No potentiation 
          occurred when fenamiphos in combination with disulfoton was 
          administered to male rats. 
    
    2.2   TOXICOLOGY - MAN
    
    2.2.1  Absorption route:  Fenamiphos may be absorbed from 
          the gastrointestinal tract, from the lungs and through intact 
          skin.  
    
    2.2.2  Dangerous doses:  
          No published information available.
    
    2.2.3  Observations on occupationally exposed workers: 
          No published information available. 
    
    2.2.4  Observations on exposure of the general population:
          No published information available.  With good agricultural 
          practice the general public should not be exposed to hazardous 
          amounts of fenamiphos. 
    
    2.2.5  Observations on volunteers: 
          No published information available.
    
    2.2.6  Reported mishaps:  
          No published information available.
    
    2.3   TOXICITY TO NON-MAMMALIAN SPECIES
    
    2.3.1  Fish: Toxic to fish
    
          LC50 (96 hour)
            Rainbow trout      0.07 - 0.11 mg/L
            Goldfish                   3.2 mg/L
            Bluegill sunfish  0.01 - 0.017 mg/L
    

    
    2.3.2  Birds:
          Oral LD50
            Mallard duck (M)       1.7 mg/kg b.w.
            Mallard duck     0.9 - 1.2 mg/kg b.w.
            Bobwhite quail   0.7 - 1.6 mg/kg b.w.
    
          Dermal LD50
            Mallard duck (M)       2.3 mg/kg b.w.
    
          LC50
            Mallard duck           316 mg/kg/diet
            Japanese quail          59 mg/kg/diet
            Bobwhite quail          38 mg/kg/diet
    
          Reproduction:  In a 19 week dietary study with mallard ducks,
          fertility, egg fragility and brain cholinesterase activity were 
          not affected at the highest dose tested (16 mg/kg/diet) while egg 
          production and hatchling survival were reduced.  The NOEL was 
          reported to be 8 mg/kg/diet. 
     
    2.3.3  Other species:  No published information 
          available.  As an organophosphate with insecticidal activity, 
          toxicity to bees would be anticipated. 
    
    3.0   FOR REGULATORY AUTHORITIES - RECOMMENDATIONS OF COMPOUND
    
    3.1   RECOMMENDED RESTRICTIONS ON AVAILABILITY
    
          [For definition of categories see the 'Introduction to Data 
          Sheets']. 
    
          Solid formulations > 30% and liquid formulations > 7.5%:
          Category 2
    
          All other formulations: Category 3
    
    3.2   TRANSPORTATION AND STORAGE
    
          All formulations:  Should be transported in clearly labelled,
          leakproof containers, away from food and drink.  Storage should 
          be under lock and key and secure from access by children and 
          other unauthorized persons. 
    
    3.3   HANDLING
          
          All formulations:  Protective clothing (see part 4) should be 
          worn for the handling of all formulations.  Adequate washing 
          facilities should be available in the immediate area.  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 tests.  Special account should be taken of the
          workers' ability to comprehend and follow instructions.  Training
          of workers in techniques to avoid contact is essential. 
    
    3.6   ADDITIONAL REGULATIONS RECOMMENDED IF DISTRIBUTED BY AIRCRAFT
    
          No recommended aerial usage reported.
    
    3.7   LABELLING
                                 DANGER - POISON
                          (Skull and cross bones insignia)
    
          Fenamiphos 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 sulfate is a pharmacological antidote. 
          Artificial respiration may be needed. 
    
    3.8   RESIDUES IN FOOD
    
          Maximum Residue Levels (MRLs) have been recommended by the 
          FAO/WHO Joint Meeting on Pesticide Residues (JMPR).  The 
          Acceptable Daily Intake (ADI) has been estimated by the JMPR at 0 
          - 0.0005 mg/kg b.w. 
    
    4.0   PREVENTION OF POISONING IN MAN AND EMERGENCY AID
    
    4.1   PRECAUTIONS IN USE
    
    4.1.1  General:  Fenamiphos is an organophosphorus 
          pesticide of high toxicity.  It is readily absorbed through 
          intact skin from the gastrointestinal tracts and by inhalation.  
          Repeated exposure may have a cumulative effect on cholinesterase 
          activity.  Fenamiphos formulations should only be handled by 
          trained personnel wearing protective clothing.  Its use is 
          severely restricted in several countries. 
    
    4.1.2  Manufacture and formulation:  TLV - 0.1 mg/m3. 
          This time-weighted average value has been determined from risks 
          associated with skin exposure and subsequent dermal absorption. 
    
          Dust and aerosol formation must be controlled, preferably by 
          mechanical means.  Protective clothing (see 4.1.3) and 
          respiratory equipment is necessary to reduce dermal and 
          inhalation exposures. 
    
    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 
          fenamiphos 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:  
          With good agricultural practice and subject to section 4.2 and 
          4.3 below, other populations should not be exposed to hazardous 
          amounts of fenamiphos. 
    
    4.2   ENTRY OF PERSONS INTO TREATED AREAS
    
          Unprotected persons should be kept out of treated areas for at 
          least 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 fenamiphos formulations should be covered 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:  Fenamiphos is an
          organophosphorus pesticide of high mammalian toxicity. It is 
          readily absorbed through intact skin and by inhalation.  It acts 
          by direct inhibition of acetylcholinesterase affecting nerve 
          transmission. 
    

    
    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 includes, 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 published information available.
    
    5.2   SURVEILLANCE TESTS
    
          Any fall in erythrocyte cholinesterase activity to 70% of the 
          pre-exposure value, 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 pre-exposure value.  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 the 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:
    
          A specific gas-chromatographic procedure for the determination of 
          residues of fenamiphos and sulfoxide and sulfone is available.  
          Some basic references are listed as follows: 
    
          Luke MA, Froberg JE, Doose GM, Masumoto HT (1981), J Assoc Off 
          Anal Chem 64(5):  1187-1195. 
    
          Peterson D, Winterlin W (1986), J Agric Food Chem, 34(2):  
          153-156.
    
          Thornton JS, (1971), J Agric Food Chem 19:  890-893. 
    
    5.3.2  Other tests in case of poisoning:  Activity of
          cholinesterase in the blood or plasma provide the most useful 
          diagnosis of poisoning. 
    
          Ellman GL et al (1969), Biochem Pharmacol 7:  88-95.
    
          Wilhelm K, & Reiner E (1973), Bull Wld Health Org, 48:  235-238.
    
                                   REFERENCES
    
    
    1.    FAO/WHO (1988), Pesticide Residues in Food - 1987 Evaluations, 
          Part II - Toxicology, FAO Plant Production and Protection Paper 
          86/2, Rome, Food and Agriculture Organization of the United 
          Nations. 
    
    2.    The Pesticide Manual, A World Compendium (9th edition 1991), 
          Worthing, C.R. and Hance, eds., British Crop Protection Council, 
          20 Bridport Road, Thornton Heath, CR4 7QG, United Kingdom. 
    
    3.    WHO (1975), 1974 Evaluations of Some Pesticide Residues in Food.  
          WHO Pesticide Residue Series No. 4, 295-333, Geneva, World 
          Health Organization. 
    
    4.    WHO (1986), Environmental Health Criteria No. 63, 
          Organophosphorus Insecticides:  A General Introduction.  
          UNEP/ILO/WHO Geneva. 
    
    5.    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). 
    
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See Also:
        Fenamiphos (PIM 777)