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    FENAMIPHOS        JMPR 1974

    IDENTITY

    Fenamiphos is a draft ISO common name.

    Chemical name

    O-ethyl O-(3-methyl-4-methylthiophenyl) isopropylphosphormidate.

    O-ethyl 4-(methylthio)-m-tolyl isopropylphosphoramidate.

    Synonyms

         Nemacur(R), phenamiphos, Bayer 68138.

    Structural Formula

    CHEMICAL STRUCTURE 9


         Molecular weight 303.3

         Empirical Formula: C13H22NO3PS

    Other information on identity and properties

         State:                   brown semi-solid (technical)
                                  white crystals (pure)

         Melting Point:           46°C (technical)
                                  49°C (Pure)

         Vapour pressure:         10-6mm Hg (at 30°C)

         Solubility:              in water approx. 700 mg/l at 20°C
                                  slightly soluble in most organic
                                  solvents

         Specific gravity (melt): 1.14

         Hydrolytic stability in propanol/water (1:1) at 40°C:

         40% degradation after 14 days            at pH 2
         no degradation after 50 days             at pH 7
         half life of 31.5 hours                  at pH 11.3

         Formulations: 5% Granular, 10% Granular, 400 E.C. (Emulsifiable
         concentration 400 g/l)

    Purity

         The minimum purity is 87%. Maximum levels of the individual
    impurities are shown in Table 1.

    TABLE 1  Impurities (maximum levels) in technical fenamiphos

    Compound                                             Maximum
                                                         level (%w/w)

    O,O-diethyl isopropylphosphoramidate                       3.0

    4-methylthiocresol                                         0.5

    O,O-bis[(4-methylthio)-3-ethylphenyl]
    isopropylphosphoramidate                                   2.0

    O,O-diethyl O-[(4-methylthio)-3-methylphenyl]
    phosphate                                                  1.0

    O-ethyl O-[(4,6-bismethylthio)-3-methylphenyl]
    isopropylphosphoramidate                                   3.0

    O-ethyl O,O-bis-[(4-methylthio)-3-methylphenyl]
    phosphate                                                  8.0

    O-ethyl O-[(4-methylthio)-3-methylphenyl] phosphate        1.0

    water                                                      0.3

    EVALUATION FOR ACCEPTABLE DAILY INTAKE

    BIOCHEMICAL ASPECTS

    Biotransformations

         The two major metabolites identified following injection into
    bean, tomato, peanut and potato stems were O-ethyl
    O-4-methylsulfinyl-m-tolyl isopropylphosphoramidate and O-ethyl
    O-4-methylsulfonyl-m-tolyl isopropylphosphoramidate, the sulphoxide
    and sulphone of the thio-ether (Waggoner, 1972). A third metabolite
    (apparently a more potent inhibitor of cholinesterase) was 
    not identified but was considered to be a further metabolite 
    resulting from the sulphoxide. Further details of this study are 
    given in the section "Fate of residues in plants". Small residues of
    the unknown metabolite may be of toxicological significance because
    of the potent anticholinesterase properties.

         The metabolic fate of labelled fenamiphos was studied in vivo
    in rats and in vitro with rat liver microsomes. The compounds were
    labelled in the ethyl (14C) isopropyl, (14C) or the thiomethyl (3H)
    positions. In vivo fenamiphos is excreted within 12-15 hours
    following a single oral dose of 2 mg/kg. In the in vitro studies a
    small quantity of an unknown metabolite possibly resulting from the
    N-dealkylation of fenamiphos was observed (Khasawinah and Flint,
    1972). Apart from this minor component, metabolism in animals and
    plants follows the same pattern: oxidation of the thioether to the
    sulphoxide and sulphone, dearylation to yield the methyl thioether
    phenol (or its sulphoxide and sulphide) and potentially dealkylation
    of the ethyl, isopropyl or isopropylamide moiety of the phosphate
    ester. Treatment of rats with fenamiphos sulphoxide or sulphone
    produced the same excretion pattern and almost identical urinary
    metabolites (Gronberg, 1969).

         When fenamiphos sulphoxide was given to a lactating cow (Gronberg
    et al., 1974) the identified components of the residue were
    fenamiphos, its sulphoxide and its desisopropyl derivative, and the
    phenols of phenamiphos, its sulphoxide and its sulphone. An
    unidentified metabolite was also detected. Quantitative details are
    given in the section "Fate of residues in animals".

    Effects on enzymes and other biochemical parameters

         Fenamiphos, as are other organophosphate esters, is an inhibitor
    of cholinesterase enzymes. The in vitro I50 values were as follows:

         Rat serum - 5.1 x 10-5M.

         Rat erythrocyte - 6.3 x 10-4M.

         Rat brain - 2.1 x 10-4M.

         The maximum inhibition of whole blood cholinesterase in vivo
    occurred in rats three hours after dosing. In vivo sensitivity of
    cholinesterase reflects the in vitro I50 values with plasma
    cholinesterase being more sensitive to inhibition than the erythrocyte
    enzyme (Löser and Kimmerle, 1971). The metabolites of fenamiphos are
    more active inhibitors than the parent molecule (Waggoner, 1972). In
    vitro inhibition of horse serum cholinesterase showed relative
    values for fenamiphos < sulfoxide = sulfone < sulfoxide metabolite.

         In vitro I50 values of chicken and monkey liver aliesterase
    (triacetin hydrolysis) and monkey cholinesterase are as follows:

         Chicken (aliesterase):   4.2 x 10-5M.

         Monkey (aliesterase):    1.0 x 10-6M.

         Monkey (cholinesterase): 4.6 x 10-6M.

         (Coulston and Wills, 1974)

         On the basis of some preliminary electrophysiological studies
    with the cat, it was estimated that a threshold dose of fenamiphos
    might fall in the range of 0.8 to 1.5 mg/kg (Coulston and Wills,
    1974).

    TOXICOLOGICAL STUDIES

    Special studies on carcinogenicity

    Mouse

         Groups of Charles River random bred Swiss white mice (125 males
    and 125 females/group) were fed fenamiphos in the diet at 0, 25 and 50
    ppm for eighteen months in a study specifically designed to evaluate
    the carcinogenic potential of the compound. Additional groups of mice
    were fed 10 ppm N-nitrosodiethylamine for eighteen months (125 males
    and 125 females); 40 ppm for six months (60 males and 60 females); and
    1000 ppm benzidine (100 females) for eighteen months as positive
    controls. Fenamiphos did not affect the incidence or pattern of
    mortality. Clinical chemistry studies performed at 18 months were
    normal. No signs of tumour formation were observed on gross or
    microscopic examination which were attributed to fenamiphos (Smith et
    al., 1972).

    Special studies on mutagenicity

    Mouse

         Groups of twelve male mice were administered fenamiphos
    intraperitoneally at 0, 0.25 and 0.50 mg/kg and mated for six
    consecutive weeks to virgin females in a standard dominant lethal
    test. A positive reference (methyl methanesulphonate) was used in this

    experiment. Fenamiphos did not induce alterations in male germinal
    cells which would be expected to lead to an early embryo mortality
    (Arnold et al., 1971).

    Special studies on neurotoxicity

    Hen

         Groups of hens (eight per group) were fed fenamiphos in the diet
    at levels of 0, 1, 3, 10, and 30 ppm for thirty days. At the end of
    the feeding experiment some animals were sacrificed and the remainder
    were observed for four weeks for neurological signs of poisoning. Food
    consumption was depressed at 30 ppm and the average body weight and
    growth of the animals at this same level was reduced. Cholinesterase
    (whole blood) depression was observed at thirty days at 3, 10 and 30
    ppm, although cholinergic signs of poisoning were not observed at any
    time. There were no indications of delayed neurotoxic effects and
    microscopic examination of brain, spinal cord, and sciatic nerve
    (stained with H&E) did not indicate delayed neurological involvement
    with fenamiphos (Kimmerle, 1970; Spicer, 1970).

         Groups of hens (ten per group) were orally administered an LD50
    dose of fenamiphos (5.0 mg/kg). The birds were observed for three
    weeks and sacrificed. No evidence of delayed neurotoxicity was
    observed either clinically or histologically while positive signs were
    observed with TOCP (Kimmerle, 1971; Spicer, 1971).

    Special studies on potentiation

    Rat

         Male rats were tested orally with fenamiphos (SRA 3886) in
    combination with disulfoton or E 154 and no potentiation of the acute
    toxicity was noted (Kimmerle, 1972c).

    Special studies on reproduction

    Rat

         A standard three generation, two litters per generation,
    reproduction study was performed with fenamiphos. Four groups of
    animals, consisting of ten male and twenty female rats per group, were
    fed fenamiphos at 0, 3, 10, and 30 ppm in the diet throughout the
    study period including mating, gestation, and suckling. Immediately
    after birth, pups were examined for malformations prior to either
    preparing for another generation or sacrifice. Five weanling rats per
    group of the F3b generation were sacrificed and macroscopic and
    microscopic examinations performed on the major tissues and organs.
    There were no apparent differences with regard to reproduction
    parameters including fertility, litter size, lactation index, growth
    of young, or on examination for malformation in any of the animals
    exposed to fenamiphos levels up to and including 30 ppm in the diet.
    It was concluded that fenamiphos had no influence on the reproduction

    of rats at dietary levels up to and including 30 ppm (Löser, 1972c;
    Cherry et al., 1972).

    Special studies on teratogenicity

    Rabbit

         Groups of fifteen artificially inseminated rabbits were orally
    administered fenamiphos at levels of 0, 0.2, and 0.4 mg/kg/day.
    Positive control groups (oral treatment with thalidomide (37.5
    mg/kg/day)) were concurrently run with this experiment. All animals
    were treated from day 6 through 18 of gestation and sacrificed on day
    29. At day 29 the young were examined for 24 hours, sacrificed and
    examined after skeletal staining. At the high level of treatment of
    fenamiphos, 2/12 instances of abortion and 2/12 premature deliveries
    were observed. No external or internal abnormalities were observed in
    the foetuses following treatment. With the exception of the animals at
    the high level of treatment where a few aborted or delivered
    prematurely, no effects on reproduction were observed with fenamiphos
    (Ladd et al., 1971).

    Acute toxicity

    TABLE 2  Acute toxicity of fenamiphos
                                                                            
                                   LD50
    Animal        Sex    Route     (mg/kg)     References
                                                                            

    Rat           M      oral      2.4-15.6    Löser and Kimmerle, 1971
                                               Kimmerle and Solmecke, 1971a

    Rat           F      oral      2.3-19.4    Kimmerle, 1972c
                                               Crawford and Anderson, 1974
                                               DuBois et al., 1967

    Rat           M      ip        3.0-3.7     ibid.

    Rat           F      ip        4.2-4.9     Löser and Kimmerle, 1971

    Rat           M      dermal    73-500      DuBois et al., 1967

    Rat           F      dermal    84-154      Kimmerle and Solmecke, 1971a

    Mouse         M      oral      22.7        Löser and Kimmerle, 1971

    Mouse         M&F    ip        3.4         DuBois at al., 1967

    Guinea Pig    M      oral      56-100      ibid.
                                               Löser and Kimmerle, 1971
                                               Kimmerle and Solmecke, 1971a

    Guinea Pig    M      ip        17.3        DuBois et al., 1967

    TABLE 2  (Cont'd.)
                                                                            
                                   LD50
    Animal        Sex    Route     (mg/kg)     References
                                                                            

    Rabbit        M      oral      10-17.5     Löser and Kimmerle, 1971
                                               Kimmerle and Solmecke, 1971a

    Cat           M      oral      Ca.10       Löser and Kimmerle, 1971
                                               Kimmerle and Solmecke, 1971a

    Dog           M      oral      Ca.10       Löser and Kimmerle, 1971
                                               Kimmerle and Solmecke, 1971a

    Hen           F      oral      5.3         Löser and Kimmerle, 1971
                                               Kimmerle and Solmecke, 1971a
                                                                            

    TABLE 3  Acute toxicity of metabolites and impurities of fenamiphos
                                                                            
                                   LD50
    Species       Sex    Route     (mg/kg)     References
                                                                            

    Fenamiphos-sulphoxide

    Rat           F      oral      10-25       Thyssen, 1974a

    Fenamiphos-solphone

    Rat           F      oral      10-25       ibid.

    4-methylthio-m-cresol

    Rat           M      oral      1418        Crawford and Anderson, 1974

    Rat           F      oral      1333>2500   ibid.
                                               Thyssen, 1974c

    3-methyl-4-methylthiophenol

    Rat           M      oral      1418        Crawford and Anderson, 1974

    Rat           F      oral      500-1000    Thyssen, 1974d
                                   1175        Crawford and Anderson, 1974

    3-methyl-4-methanesulphonylphenol

    Rat           M      oral      1250        ibid

    Rat           F      oral      1000        Thyssen, 1974e
                                   1854        Crawford and Anderson, 1974
                                                                            

         Impurities identified as components of the technical mixture
    (aryldiamide, diarylamide, diaryl ethyl ester, diethyl ester,
    diethylmonamide, di-SCH3 compound, ethyl aryl ester, ethyldiamide,
    and 4-methylthio-3-cresol) were tested for their acute toxic
    properties to rats. At a dosage of 1.5 times the acute LD50 of
    fenamiphos none of the materials were toxic (Crawford and Anderson,
    1973b).

         Technical fenamiphos administered to the skin of rabbits as an
    acetone solution at 50 mg/kg resulted in a slight erythema and was not
    considered as a primary irritant. Technical fenamiphos applied to the
    conjunctival sac of rabbits (100 mg/kg as a crystalline material) was
    irritating to the eye. This irritation was believed to be a mechanical
    rather than a physiological effect (Crawford and Anderson, 1971).

         A 15% granular formulation was examined for dermal and inhalation
    toxicity properties and at the highest level examined (200 mg/kg and
    20 mg/l respectively) no toxicity was observed (Crawford et al.,
    1970b; Crawford and Anderson, 1972a). The rat oral LD50 of a 15%
    granular formulation was 66.6 mg/kg for male rats and 62.7 mg/kg for
    female rats (DuBois and Kinoshita, 1970). A 5% or 10% granular
    formulation, administered at up to 500 mg/kg to the backs of rats
    resulted in depressed cholinesterase activity values. Mortality was
    not observed at the maximum dose tested and it was considered that the
    granular formulation was not a dermal hazard although the material was
    rapidly absorbed into the body (Kimmerle and Solmecke, 1971b). The
    acute dermal toxicity and dermal and eye irritation properties of a
    liquid formulation (37.4% a.i.) were tested in rabbits. The acute
    LD50 was 75.7 mg/kg and 71.5 mg/kg to male and female rabbits
    respectively (Crawford et al., 1970a; Crawford and Anderson, 1972b).
    When applied to intact and abraded skin at a dose of 0.25 ml (0.085 mg
    a.i.), fenamiphos was not found to be a primary irritant. Fenamiphos
    (0.1 ml, equivalent to 0.034 mg a.i.) was an irritant when applied to
    the conjunctival sac of rabbits. Control formulation data were not
    reported (Crawford and Anderson, 1973c). The acute rat oral LD50 of a
    35% liquid formulation was calculated to be 24.8 mg/kg (equivalent to
    8.7 mg fenamiphos /kg). Inhalation toxicity studies with this
    preparation using a small particle size distribution (1-3 microns)
    resulted in an LC50 value of 0.175 and 0.091 mg/l following one and
    four hour exposure respectively (DuBois and Kinoshita, 1971). Studies
    with rodents administered fenamiphos by inhalation at doses up to 0.23
    mg/l for one to four hours exposure as a static spray showed that
    rabbits and guinea pigs were more tolerant of the acute effects than
    rats and mice. A one hour LC50 value for mice was 0.06 mg/l and for
    rats 0.23 mg/l while rabbits and guinea pigs were unaffected at these
    concentrations (Kimmerle and Solmecke 1971a; 1972b). Acute oral
    administration of 2.5 mg/kg to rabbits had no effect on several liver
    function tests including BSP, SGPT and SDH activity at 1 and 24 hours
    and seven days after treatment (Kimmerle and Solmecke 1971a).

         Studies performed on male rats indicated that, following
    poisoning, the administration of atropine and/or 2-PAM or Toxogonin
    would reduce the acute lethal dose by a factor of approximately two.
    As with other organophosphorus compounds, rapid administration of
    atropine and oxime reactivator following poisoning would afford some
    protection and would alleviate the cholinergic signs of poisoning
    (Kimmerle, 1972a; DuBois et al., 1967).

    Short term studies

    Rat

         Groups of rats (fifteen males and fifteen females per group,
    thirty males and thirty females were used as controls) were fed
    fenamiphos in the diet at 0, 4, 8, 16, and 32 ppm for twelve weeks.
    Male and female rats from the highest dose group exhibited signs of
    cholinergic stimulation in the first two months of the test.
    Behavioral differences in all other groups were not apparent. There
    were no differences from the control in the average of any group with
    regard to food consumption and growth. With the exception of
    cholinesterase inhibition, there was no apparent effect on group
    averages of haematological parameters examined. Plasma cholinesterase
    depression was observed at 8 ppm. A no-effect level, based upon plasma
    cholinesterase, was observed at 4 ppm. Gross and microscopic
    pathological examination was performed on tissues and organs at the
    conclusion of the experiment. A slightly increased liver weight,
    observed in males at 16 and 32 ppm, was not reflected in the
    calculation of relative organ-to-body weight ratios nor in the
    histological examination. Based on cholinesterase depression, 4 ppm in
    the diet was a no-effect level in this experiment (Löser, 1968b;
    Mawdesley-Thomas and Urwin, 1970a).

         Groups of male rats (15 per group) were administered fenamiphos
    orally or by intraperitoneal injection daily, 5 days/week for 60 days.
    The animals all survived a dose range of 1.5 (ip) to 1.7 (oral)
    mg/kg/day with no evidence of a cumulative toxicological effect due to
    fenamiphos (Kimmerle and Solmecke, 1971a). In an earlier study female
    rats survived daily ip administration of 1 mg/kg for 60 days while 40%
    of those administered 2 mg/kg did not survive. All rats died at 3
    mg/kg administered by intraperitoneal injection (DuBois and Flynn,
    1968). These studies indicate little if any cumulative toxicity.

    Dog

         Groups of beagle dogs (two males and two females/group) were fed
    fenamiphos in the diet at 0, 2, 6, and 18 ppm for three months.
    Behavioral abnormalities, evidenced by signs of cholinergic
    stimulation, were evident at 18 ppm in the diet and growth of females
    at this high level was reduced. Average haematological and clinical
    chemistry values including liver function tests, kidney function tests
    and urinalyses were not apparently affected by fenamiphos in the diet.
    Averages of plasma and red blood cell cholinesterase values were

    depressed at 4 ppm in the plasma of both males and females. At 2 ppm
    no effect on the average red cell cholinesterase values was found
    while plasma cholinesterase was depressed (20-30%) in both sexes.
    Gross morphological examination of tissues and organs at the
    conclusion of the study indicated no abnormal effects of fenamiphos in
    the diet (Löser, 1968a).

         Groups of beagle dogs (two males and two females/dose, three of
    each sex were used in the control group) were fed fenamiphos in the
    diet at levels of 0, 1, 2 and 5 ppm for twelve weeks. There was no
    effect of feeding fenamiphos at levels up to and including 5 ppm in
    the diet on the average of any of the parameters examined including
    haematology, liver function tests, clinical chemistry tests, kidney
    function tests, and gross and microscopic examination of tissues and
    organs. As with other studies, cholinesterase was the only parameter
    significantly affected, with the females being more susceptible than
    the males and the plasma being more sensitive to inhibition than red
    blood cell. Erythrocyte cholinesterase was unchanged at 2 ppm while
    plasma cholinesterase was slightly depressed. One ppm in the diet had
    no effect on plasma cholinesterase. As the depression of plasma
    cholinesterase was minimal and transient at 2 ppm it might be
    considered that this would be a no-effect level in this experiment
    (Löser, 1969; Mawdesley-Thomas and Urwin, 1970b).

         As an extension of the previous short term study in dogs (Löser,
    1969), an additional two male and two female dogs were fed fenamiphos
    in the diet at 10 ppm for three months. Two male and two female
    animals were also maintained as a control. There was no mortality over
    the course of the experiment and a very slight deviation in the
    average body weight of both males and females was noted. Because of
    the small sample population, the slight weight differences cannot be
    fully evaluated. There was no effect of feeding fenamiphos on any of
    the haematological parameters examined. Urinalysis, clearance
    examinations, blood sugar and cholesterol were normal over the course
    of the experiment. Cholinesterase activity was significantly depressed
    in both plasma and erythrocytes and in both male and female dogs. In
    addition, several abnormalities were noted with regard to some of the
    serum enzyme parameters related to liver function after three months
    of feeding, especially in male dogs. Alkaline phosphatase and SGPT
    activity were significantly increased. Following gross and microscopic
    examination of tissues and organs, no significant differences were
    noted between the control and those animals fed 10 ppm. The abnormal
    findings in some enzyme parameters related to liver functions,
    predominantly in males at three months of feeding 10 ppm in the diet,
    were not accompanied by pathological findings at autopsy nor confirmed
    in another test where fenamiphos was fed at levels of 18 ppm in the
    diet. They are considered a transient occurrence and not directly
    related to the presence of fenamiphos in the diet (Löser, 1970;
    Thompson et al., 1972a).

         Groups of pure bred beagle dogs (four males and four females per
    group) were fed fenamiphos in the diet at levels of 0, 0.5, 1, 2, 5,
    and 10 ppm for two years. There were no significant effects noted with
    fenamiphos at any dietary level with regard to growth, food
    consumption or any of the standard clinical and physiological
    examinations made during the course of the study. One dog died after
    being fed 0.5 ppm in the diet. This dog was considered to have died of
    pneumonia and its death was not related to administration of
    fenamiphos. Gross and histological examinations of all tissues and
    organs at the conclusion of study did not reveal any abnormal
    developments considered to have been a result of feeding fenamiphos.
    The only significant physiological effect observed was
    anti-cholinesterase activity which was marginally depressed in plasma
    at 2 ppm. As with other species, the plasma appears to be the most
    sensitive indicator of exposure with a no-effect level being 1 ppm in
    the diet (equivalent to 0.029-0.036 mg/kg/day) (Löser, 1972b; Thompson
    et al., 1972b).

    Long term studies

    Rats

         Groups of SPF derived Wistar strain (forty males and forty
    females per group, eighty males and eighty females used as controls)
    were fed fenamiphos in the diet, at concentrations of 0, 3, 10, and 30
    ppm for two years. Behavioral abnormalities were evident, as signs of
    cholinergic stimulation, only during the first six weeks of feeding at
    30 ppm. After six weeks of feeding, the obvious anticholinesterase
    effect disappeared and was not evident for the remainder of the two
    year study. There were no differences in averages at any feeding level
    on growth, mortality, food consumption, haematological values,
    clinical chemistry values or liver and kidney function tests. Urine
    examinations as well as blood sugar and cholesterin values were
    normal. Thyroid weights and thyroid-to-body weight ratios of females
    were heavier than normal at 30 ppm. All other major tissues and organs
    appeared normal under gross and microscopic examination. The thyroid
    weight in females at 30 ppm was high but was not accompanied by an
    abnormal tumour development, goitre or by unusual histological
    findings.

         Cholinesterase determinations indicated that plasma
    cholinesterase was the most sensitive parameter. At 10 ppm in the
    diet, fenamiphos inhibited plasma cholinesterase. No significant
    effects were observed at 3 ppm in the diet (equivalent to 0.17-0.23
    mg/kg bw/day) (Löser, 1972a; Cherry and Newman, 1973).

    COMMENTS

         Fenamiphos, an acutely toxic organophosphate ester, is rapidly
    absorbed as evidenced by rapid onset of cholinergic signs of
    poisoning. In animals fenamiphos is rapidly degraded, predominantly
    through oxidation to acutely toxic products. Fenamiphos does not
    appear to affect biochemical systems other than cholinesterase.

    Testing for the delayed neurotoxic effect commonly seen with TOCP was
    negative. Short term and long term dietary studies in both rats and
    dogs have indicated, with the exception of cholinesterase depression,
    no unusual effects. In long term studies with rats, transient
    behavioural abnormalities were observed during the first six weeks of
    feeding, which disappeared and were not evident for the remainder of
    the study. Female rats are more susceptible than males to
    cholinesterase depression. Plasma cholinesterase depression is a
    better indicator of exposure than red blood cell cholinesterase. Based
    on plasma cholinesterase depression, a no-effect level in a two-year
    rat study is considered to be 3 ppm in the diet and in a two year dog
    study, 1 ppm in the diet. Long term studies in rats and mice reported
    to the Meeting did not show a carcinogenic effect. Although there are
    no studies available in man, sufficient data are available and the
    Meeting allocated an ADI using the more sensitive species, the dog.

    TOXICOLOGICAL EVALUATION

    Level causing no toxicological effect

         Rat: 3 ppm in the diet equivalent to 0.17 mg/kg bw.

         Dog: 1 ppm in the diet equivalent to 0.029 mg/kg bw.

    ESTIMATE OF ACCEPTABLE DAILY INTAKE FOR MAN

         0 - 0.0006 mg/kg bw.

    RESIDUES IN FOOD AND THEIR EVALUATION

    USE PATTERN

         Fenamiphos is an organophosphorus compound with a systemic action
    and a powerful nematicidal effect. It is active against root-knot,
    cyst-forming and free-living nematodes and has important applications
    against sucking insect pests and spider mites. Fenamiphos is
    commercially used in the USA, Australia, Spain, the Cameroons,
    Caribbean, Chile, Columbia, Costa Rica, Ecuador, Guatemala, Ivory
    Coast, Jamaica, Martinique, Mexico, Nicaragua, San Salvador and
    Uruguay. Registration proceedings and trials are in progress in
    several other countries.

         Fenamiphos is formulated as 5 and 10% granules and as a 40%
    emulsifiable concentrate.

    Pre-harvest treatments

         Fenamiphos is formulated as a granular product and as an
    emulsifiable concentrate. Both formulations are recommended chiefly
    for treatments in banana, pineapple, vegetable (tomatoes, brassicas,
    peppers, eggplants), tobacco, coffee, groundnut and citrus crops.
    Application is usually made to the soil at sowing, planting and

    transplanting, and in established crops. The general dose rate is 5 to
    10 kg active ingredient per hectare for broadcast (overall)
    application, but is reduced for band application according to band
    width. Furthermore, the emulsifiable concentrate is suitable for dip
    treatments of banana seedlings and for foliar spraying of pineapples.
    Details of uses and recommendations are given in Table 4.

        TABLE 4  Use Pattern of fenamiphos (All applications are pre-harvest against nematodes)

                                                                                                

                                                                                     No. of
                     Application rate                                                treatments
    Crop                  a.i.           Type of Application         Formulation1    per year
                                                                                                

    Bananas          1.5-2.5 g/m2        At planting                 G
                     3.0 g/plant         Soil treatment in
                                         established crop            G               3-4

                     4-5 kg/ha           In irrigation
                                         canals or direct
                                         to soil                     EC              2

                     1-1.5 g/corm        Dip treatment
                                         pre-planting plus
                                         soil application            EC

                     2 or 1.5 g/
                     planting position
                     (but no more than
                     total of 3 g/
                     planting position)                              G

    Pineapples       10-40 kg/ha         Broadcast treatment
                                         pre-planting of
                                         crowns and slips            G

                     5-20 kg/ha          Broadcast treatment
                                         pre-planting of
                                         crowns and slips
                                         in combination with         G

                     3-5 kg/ha           foliar spraying                             3 in
                                         post-planting               LC              established
                                                                                     crop

                     15 kg/ha            Foliar spray
                                         application at
                                         planting, repeat
                                         after an interval
                                         of 2 months                 EC              2

    TABLE 4  (Cont'd.)

                                                                                                

                                                                                     No. of
                     Application rate                                                treatments
    Crop                  a.i.           Type of Application         Formulation1    per year
                                                                                                

    Tomatoes         1-2.5 g/m2          Immediately before
                                         or after sowing             G

                     5-10 kg/ha          Broadcast/overall
                                         application                 G,
                                         pre-planting                EC

    Brassicas        5-8 kg/ha           Broadcast/overall
                                         application                 G,
                                         pre-planting                EC

    Tobacco          1-2.5 g/m2          Before or immediately
                                         after sowing or             G

                     0.1-0.2 g/plant     at transplanting or
                                         in established crop         G               1

                     5-10 kg/ha          Broadcast/overall
                                         application                 G,
                                         pre-planting                EC

    Coffee           1-2.5 g/m2          Seedbed treatment           G
                     1.5-2.5 g/shrub     In established crop         G               2-3

    Groundnuts       3-5 kg/ha           Broadcast/overall
                                         application                 G,
                                         pre-sowing                  LC              1

    Cucurbitaceae    0.15-0.2 g/         Band application
                     planting hole or    at sowing                   G
                     1.5-2.5 kg/ha

    Peppers          5-8 kg/ha           Broadcast application
                                         at sowing or at
                                         transplanting               G               1

    Eggplant         5-8 kg/ha           Broadcast application
                                         at sowing or at
                                         transplanting               G               1

    Citrus           1-1.5 g/m2          Seedbed treatment           G

                     2-3 g/tree          Treatment in nursery        G

                     1.5-3 g/tree        In established crop         G, LC           2-3

    TABLE 4  (Cont'd.)

                                                                                                

                                                                                     No. of
                     Application rate                                                treatments
    Crop                  a.i.           Type of Application         Formulation1    per year
                                                                                                

    Potatoes         5-10 kg/ha          Broadcast/overall           G, EC,
                                         treatment pre-planting      LC              1

    Pyrethrum        5-8 kg/ha           Broadcast application
                                         at planting                 G

    Ornamentals      1.5-3 g/m2          In established crops        G

    Cotton           1.7-3.5 kg/ha       Band application
                                         (band width of              G,
                                         30-45 cm.) at sowing        LC

    Beets            3-(6) kg/ha         Band application
                                         immediately after
                                         sowing or during            G,
                                         emergence                   EC

    Soybeans         5-8 kg/ha           Broadcast/overall
                                         application                 G,
                                         pre-sowing                  LC              1

    Beans            5-8 kg/ha           Broadcast application
                                         pre-sowing                  G               1

    Grapes           2-3 g/plant                                     G               1

    Strawberries     10 kg/ha            Broadcast application
                                         pre-planting                G

                     300 g/1000          Post-planting or            G
                     metres of row       post-harvest

    Lawns            10-20 kg/ha         Broadcast application       G
                                                                                                

    1  G = Granules;   EC = Emulsifiable concentrate;   LC = Liquid concentrate.
    

    Post-harvest treatments

    No recommended uses.

    Other uses

    Fenamiphos is recommended for use on ornamentals (granular
    formulation).

    RESIDUES RESULTING FROM SUPERVISED TRIALS

         The residues of fenamiphos together with its sulphoxide and
    sulphone resulting from supervised trials in a wide range of crops are
    shown in Table 5. In most crops, residues were below 0.05 mg/kg. The
    exceptions were grapes, lettuce, potatoes, strawberries and tomatoes
    which contained up to about 0.1, 0.5, 1, 0.7 and 0.3 mg/kg
    respectively. Residues in tobacco were much higher, with respective
    maximum levels in green, cured and fermented tobacco of about 12, 140
    and 100 mg/kg.

    FATE OF RESIDUES

    In animals

         A feeding study was carried out on a lactating dairy cow to
    determine whether fenamiphos sulphoxide, found in plants as the major
    metabolite, would be incorporated into milk and animal tissues either
    as the intact compound or in metabolized form (Gronberg et al., 1974.
    See also "Biotransformations"). A single dose of 0.8 mg/kg body
    weight, corresponding to 27 ppm in the diet, of ring-14C fenamiphos
    sulphoxide was administered. Four hours after application the label
    was distributed as follows. Urine 39%, faeces <0.1%, rumen 47%,
    tissues 1.4%, bile 0.1%, omasum, abomasum and milk <0.1% each; total
    recovery 88%. The following compounds were found: fenamiphos (I),
    fenamiphos sulphoxide (II), desisopropyl-fenamiphos (III), phenol of
    fenamiphos (IV), phenol of fenamiphos sulphoxide (V), phenol of
    fenamiphos sulphone (VI) and "unknown" (VII). The levels of these
    residues in tissues and milk are shown in Table 6.

         Of the dose, 18% was reduced to the parent fenamiphos, apparently
    by microorganisms. At 4 hours 82% of the activity in whole blood and
    87% of the activity in urine was identified as conjugated phenols.

         The residues of fenamiphos in poultry eggs and tissues were
    determined by Gronberg et al. (1973). Laying hens were fed for 14 days
    with carbon-14 ring-labelled fenamiphos in feed at 0.06, 0.18 and 0.65
    ppm concentration. During this time, residues in eggs were below the
    detection limit of 0.003 mg/kg. At slaughter, all tissue residues from
    birds given feed containing 0.65 ppm were below the limit of
    determination of 0.003 to 0.005 mg/kg, although very low residues were
    detectable in some tissues.



    
    TABLE 5  Residues of fenamiphos and metabolites resulting from supervised trials

                                                                                                                                               

                                                           Rate of                                               Residues, fenamiphos and
                                                           application          Interval       No. of          sulphoxide and sulphone, mg/kg
    Crop             Country              Formulation1     (kg a.i./ha)         (days)         analyses           Range               Average
                                                                                                                                               

    Apples           Australia            10% G            22.4                 334             1              n.d.2                 n.d.2

    Bananas,         Central
    peel             America              10% G            2.8-12 g
                                                           a.i./plant           1-195          41              <0.025-0.3             <0.025
    pulp                                                                                                       <0.025                 <0.025

    Bananas,         Ivory Coast          5% G             10 g a.i./plant      1-14            4              <0.02                  <0.02
    peel

    pulp                                                                                                       <0.02                  <0.02

    peel                                                                        28-88           3              0.06-0.1               0.07

    pulp                                                                                                       0.03-0.08              0.05

    Broccoli         USA                  3% G;

                                          15% G            6.72                 65-101          8              <0.01-0.04             0.02

                                          15% G            10.0                 92              1              0.2                    0.2

    Brussels
     Sprouts         USA                  3% SC;

                                          15% G            6.72-10.0            107-133         5              <0.01-0.02             <0.01

    Cabbage          USA                  3% SC;

                                          15% G            6.72-10.0            55-108         14              <0.01-0.02             0.01

    TABLE 5  (Cont'd.)

                                                                                                                                               

                                                           Rate of                                               Residues, fenamiphos and
                                                           application          Interval       No. of          sulphoxide and sulphone, mg/kg
    Crop             Country              Formulation1     (kg a.i./ha)         (days)         analyses           Range               Average
                                                                                                                                               

                     Australia            40% EC           4.5                  42-106          6              n.d.2                  n.d.2

    Carrots          USA                  15% G            6.72                 96-160          9              <0.01-0.05             0.01

    Cauliflower      USA                  3% SC;

                                          15% G            6.72-10.0            97-111         12              <0.01-0.04             0.02

    Coffee           Brazil               -                1-2 g a.i./plant     14-15           6              <0.02-0.07             0.05
    beans,            Central
    green             America                                                   28-30           6              <0.02-0.09             0.05

                                                                                56-62           4              <0.02-0.05             0.03

                                                                                90              2              0.03; 0.05             0.04

    Cottonseed       USA                  3% SC;

                                          15% G            1.12                 157-196        10              <0.01                  <0.01

    Cotton           USA                  3% SC;
    gin trash                             15% G            1.12                 161-196         8              <0.01                  <0.01

    Cotton           USA                  3% SC;
    foliage                               15% G            1.12                 143-148         4              <0.01-0.1              0.04

    Grapefruit       USA                  3% SC;
    peel                                  15% G            33.6 - 50.4          183-184         1              <0.01                  <0.01

    pulp                                                                                                       <0.01                  <0.01

    whole fruit                                                                                                <0.01                  <0.01

    TABLE 5  (Cont'd.)

                                                                                                                                               

                                                           Rate of                                               Residues, fenamiphos and
                                                           application          Interval       No. of          sulphoxide and sulphone, mg/kg
    Crop             Country              Formulation1     (kg a.i./ha)         (days)         analyses           Range               Average
                                                                                                                                               

    Grapes           Australia            5% G
                                          43% EC           5.6 - 14.7           145-147         2              n.d.2                  n.d.2

                                                           22.0                 145-147         1              0.03                   0.03

                                                           44.0                 145-147         1              0.08                   0.08

    Leaf-lettuce     USA                  3% SC            11.2                 46              1              0.3                    0.3

    Head             USA
    lettuce,                              3% SC;
    head                                  15% G            11.2                 61-72           4              0.02-0.1               0.08

    wrapper leaves                                                                                             0.09-0.5               0.3

    discard leaves                                                                                             0.09-6.5               1.9

    Lemons,          USA
    whole fruit                           3% SC            33.6                 184             1              0.01                   0.01

    Limes,           USA                  3% SC;
    whole fruit                           15% G            33.6                 147             2              <0.01                  <0.01

    Melons           Guatemala

                     Australia            5% G

                     Egypt                40% EC           1.6-10.0             56-112          5              n.d2-0.05             n.d.2

    Oranges,         USA                  3% SC;           22.4-50.4            182-366         4              <0.01-0.1              0.04
    peel                                  10% G;
                                          15% G

    TABLE 5  (Cont'd.)

                                                                                                                                               

                                                           Rate of                                               Residues, fenamiphos and
                                                           application          Interval       No. of          sulphoxide and sulphone, mg/kg
    Crop             Country              Formulation1     (kg a.i./ha)         (days)         analyses           Range               Average
                                                                                                                                               

    pulp                                                                                        4              <0.01                  <0.01

    whole fruit                                                                                 5              <0.01-0.02             0.01

    whole fruit      Australia            5% G;

                                          40% EC           11.2-22.4            21-139         10              n.d.2                  n.d.2

    Peanuts,         USA                  3% SC;
    kernels                               10% G            4.51-13.45           122-148         5              <0.01-0.02             <0.01

    shells                                                                                                     (0.01-0.2              0.06

    vines                                                                       98-148          5              0.02-4.3               2.3

    Pineapples       Hawaii, USA          3% SC;
                                          10% G            44.8-112             238-658        10              <0.01-0.03             <0.01
                                          3% SC
                                          (foliar spray)   5.6                  1-29           20              <0.02-4.0              0.5

    Potatoes         USA                  3% SC;
                                          15% G (row
                                          appl)            6.1                  41-58           3              <0.02-1.2              0.7

                                                                                71-106          7              <0.01-1.0              0.15

    Potatoes,        USA, Canada,         3% SC;
    whole            Fed. Rep. of         15% G
                     Germany, UK,         (broadcast
                     Australia                             4-5-11.2             67-203         23              n.d.2-0.45             0.07

    peel                                                                                        1              0.07                   0.07

    TABLE 5  (Cont'd.)

                                                                                                                                               

                                                           Rate of                                               Residues, fenamiphos and
                                                           application          Interval       No. of          sulphoxide and sulphone, mg/kg
    Crop             Country              Formulation1     (kg a.i./ha)         (days)         analyses           Range               Average
                                                                                                                                               

    flesh                                                                                       1              0.07                   0.07

    Sweet            USA                  3% SC;
     Potatoes                             15% G
                                          (broadcast)      6.72                 108-143         8              <0.01-0.04             0.01

                                          3% SC;
                                          15% G
                                          (row appl)       4.0-6.1              108-143         8              <0.01-0.06             0.01

    Soybeans,        USA                  3% SC;
    bean, green                           15% G            11.2                 75-117         12              <0.01-0.09             0.04

    vine, green                                                                 75-117         12              <0.01-12               2.9

    bean, dry                                                                   131-159        11              <0.01-0.03             0.01

    Strawberries     Australia            5% G
                                          40% EC           16.5-22.5            36-121          6              0.03-0.7               0.2

    Sugarbeets,      USA                  3% SC;
    tops                                  15% G            6.72-10.0            119-187         9              <0.01-0.08             0.01

    beets                                                                                                      <0.01-0.03             0.01

    Tangerines,      USA                  3% SC;
    peel                                  15% G            33.6                 247-251         2              0.07; 0.3              0.2

    pulp                                                                                        2              <0.01; 0.03            0.02

    whole fruit                                                                                 1              0.03                   0.03

    TABLE 5  (Cont'd.)

                                                                                                                                               

                                                           Rate of                                               Residues, fenamiphos and
                                                           application          Interval       No. of          sulphoxide and sulphone, mg/kg
    Crop             Country              Formulation1     (kg a.i./ha)         (days)         analyses           Range               Average
                                                                                                                                               

    Tobacco          Australia            40% EC                                50-95           4              0-5-4.8                1.9

    Tobacco,         USA                  3% SC;           6.72                 4               3              0.9-7.8                3.5
    green                                 15% G                                 7               3              0.8-7.0                2.9

                                                                                11              3              0.8-3.3                1.8

                                                                                14              3              1.4-12                 5.2

                                                                                21              3              1.2-4.9.               2.5

                                                                                28              3              0.4-4.2                1.7

                                                                                35              3              0.25-3.6               1.4

                                                                                36-148         13              0.02-4.8               1.0

    air cured                                                                   88-106          2              3.2; 4.2               3.7

    flue cured                                                                  85              2              11; 13                 12

    cured                                                                       75-91           6              4.5-140                33

    aged                                                                        75-92           3              5.7-16                 11

    fermented                                                                   89              1              98                     98

    Tomatoes         USA,                 3% SC;

                     Canada               15% G            11.2-16.8            61-89          10              <0.01-0.3              0.1

    TABLE 5  (Cont'd.)

                                                                                                                                               

                                                           Rate of                                               Residues, fenamiphos and
                                                           application          Interval       No. of          sulphoxide and sulphone, mg/kg
    Crop             Country              Formulation1     (kg a.i./ha)         (days)         analyses           Range               Average
                                                                                                                                               

                     Australia            5% G;
                                          40% w/v          9.8-11.2             78-161          5              <0.05                  <0.05

                     Fed. Rep, of
                     Germany              5% G             9.8-12.2             79-161          5              n.d.3                  n.d.3
                                                                                                                                               


    1   EC = emulsifiable concentrate;   G = granules;   SC = spraying concentrate.   n.d. = <0.01.

    2   <0.01 mg/kg.

    3   <0.05 mg/kg.
    

    TABLE 6  Residues, mg/kg, in tissue and milk of cow fed fenamiphos
             sulphoxide  (Gronberg et al., 1974)

                                                                            

    Compound1      Fat         Meat        Liver       Kidney       Milk
                                                                            

    I              0.004       n.d.2       0.006       n.d.         n.d.

    II             n.d.        n.d.        0.002       n.d.         0.002

    III            0.002       n.d.        0.005       0.16         0.004

    IV             0.005       0.001       0.029       0.86         0.005

    V              0.003       0.003       0.021       0.36         0.025

    VI             n.d.        n.d.        n.d.        0.01         0.004

    VII            0.002       0.005       0.036       0.25         0.020
                                                                            

    1  For identities of compounds, see text.

    2  n.d., not detectable, = <0.001 mg/kg.


    In plants

         Various investigations of the metabolism of fenamiphos in plants
    and soil demonstrate the rapid thiooxidation of the parent compound to
    the sulphoxide and sulphone. Both metabolites are detoxified by
    hydrolysis, generally followed by glucosylation of the phenolic
    products.

         Fenamiphos-14C,3H was injected into the stems of beans,
    tomatoes, peanuts and potatoes and the plants were harvested at 7, 14,
    21 and 28 days (Waggoner, 1972. See also "Biotransformations"). Two
    major metabolites were identified by TLC, isotopic ratios, IR, and MS
    as the sulphoxide and sulphone of fenamiphos. The sulphoxide was the
    major metabolite, accounting for 33-41% of the residue, followed by
    the sulphone (31-33%), both after 7 days' treatment. Two minor
    metabolites containing intact phosphoramidate structures accounted for
    not more than 1.5 and 0.2% of the total residue.

         Khasawinah studied fenamiphos metabolism in carrots (1973a),
    tomatoes (1973b), cabbages (1973c), soybeans (1972b) and tobacco
    plants (1971) following soil application, and in snap beans (1972a)
    after both soil treatment and stem injection; 14C-ring, 14C-1-ethyl
    and 3H-methylthio labelled fenamiphos were used.

         Carrots readily absorbed and metabolized fenamiphos and its major
    soil foliage and 14C from the ethyl group was detected in the foliage
    and carrots. This 14C was probably incorporated into lipids,
    pigments, sugars and structural elements such as cellulose.
    Water-soluble residues were mainly conjugates of the sulphoxide and
    sulphone phenols. No parent fenamiphos was detected. Residues of the
    sulphoxide and sulphone were below 0.06 mg/kg in both carrots and
    foliage. At the end of the growing period, soil residues were 2.7
    mg/kg fenamiphos equivalents (one third of the amount applied) of
    which 65% consisted of the sulphoxide and sulphone in the ratio 4:1.

         Results with tomatoes were similar. Sulphoxide and sulphone
    residues reached a peak of 0.2-0.3 mg/kg 30-40 days after treatment,
    and no parent compound was detected later than 40 days. The results
    showed the stability of the thio-methyl-ring linkage.

         Comparable results were obtained with head cabbage. An
    organosoluble polar metabolite with an apparently intact
    phosphoramidate structure was detected soon after treatment and
    declined gradually to insignificant levels.

         In tobacco plants the sulphoxide reached a peak in less than one
    week, and then decreased as the sulphone increased. At the end of the
    growing period the ratio of sulphoxide to sulphone was about 3:2.

         Soybeans were planted in soil that had been treated with
    14C-ethyl, 3H-methylthio fenamiphos and cropped with tobacco for one
    growing season. The soil at soybean planting contained 0.65 mg/kg
    fenamiphos sulphoxide, 0.07 mg/kg fenamiphos sulphone and 0.18 mg/kg
    fenamiphos equivalents as unextractable material. Nineteen days old
    soybean seedlings contained 16.9 mg/kg (fresh weight basis) of these
    two soil metabolites in a sulphoxide: sulphone ratio of 73:17. In the
    mature plant (150-day growing period), the total concentration of the
    two metabolites, found in equal proportions, was 3.5 mg/kg in the dry
    leaves and 0.19 mg/kg in the dry beans. The water-soluble
    radioactivity consisted mainly of the glucose conjugate of the
    sulphone phenol. The insoluble radioactivity was not characterized.

         The fate of 14C1-ethyl and 3H-methylthio fenamiphos was
    investigated in snap beans following stem injection and soil treatment
    in systems designed for the recovery of the applied nematicide. The
    study demonstrated volatile 14C radioactivity, presumably as CO2.
    40% of the stem-injected and 12% of the soil-applied fenamiphos was
    recovered in this form. Volatile tritium radioactivity was less, 7.4%
    and 1.3% of the amounts applied by stem-injection and soil treatment,
    respectively. The metabolites formed by both methods of application
    were fenamiphos sulphoxide, fenamiphos sulphone and the sulphoxide and
    sulphone phenols in the free form or conjugated with glucose.

         The metabolism of similarly labelled fenamiphos applied by stem
    injection, soil drench or spray to fruited pineapple plants was
    studied by Flint (1973). Soil treatment at 20 pounds a.i./acre
    resulted in maximum total radioactive residues in fruit of 0.086 mg/kg
    fenamiphos equivalents at 90 days after treatment. Metabolites
    identified in fruit and foliage were identical to those previously
    found in several other plant and animal systems.

    In soil and water

         Khasawinah (1970) treated the top 1.5 cm of a sandy loam soil, in
    which tobacco was growing, with labelled fenamiphos. One third of the
    applied amount was taken up by the growing plants during an 11-week
    period. The major product in the soil was the sulphoxide, with small
    quantities of the sulphone. No hydrolysis products of the parent
    compound or its oxidation products were detected in the soil extracts.
    None of the radioactivity was leached into the drainage water, and all
    of it remained in the root zone. About 22% of the radioactivity
    remaining in the soil after 177 days was bound to clay particles and
    was unextractable.

         Fenamiphos was studied for soil runoff, leaching, adsorption, and
    stability in water by Flint et al. (1971) and Church (1971). It was
    moderately adsorbed by sandy loam and silt loam soil. Fenamiphos
    residues in runoff water were less than 3.4% of the applied compound
    over a 37-day interval during which 2.3 to 3.7 inches of irrigation
    were applied; the application rate of fenamiphos was 22.5 kg a.i./ha.
    The leaching of fenamiphos from the three types of soil was inversely
    proportional to the adsorptivity of the soils. It was estimated that
    111 inches of rainfall would be needed for clay loam soil and 75
    inches for sandy loam to leach fenamiphos to a depth of 12 inches.

         Fenamiphos was relatively stable in aqueous systems at pH 5 and 7
    in the laboratory but declined rapidly with a half-life of 4.8 days in
    a simulated field pond at PH 7 and average temperature of 29°C.

         The leaching of "aged" fenamiphos residues in sandy loam soil was
    investigated by Tweedy et al. (1974). Ring-14C fenamiphos was
    incubated with sandy loam soil under greenhouse conditions for 30 days
    and then applied to the top of a sandy loam soil column 2.9 inches in
    diameter and 12 inches high. Distilled water, equivalent to 0.5
    acre-inch/day was added daily for 45 days. Of the radioactivity
    recovered from the system, 77.5% was found in the top fourth of the
    column and only 2.3% was recovered in the leachate. The majority of
    the activity, 65%, apparently did not move at all.

         The metabolism of fenamiphos soil residues under aerobic and
    anaerobic conditions was investigated by Shaw and Flint (1974).
    Fenamiphos, labelled with tritium in the methylthio group or with
    carbon-14 uniformly throughout the aromatic ring, was used in this
    study. The results indicated that anaerobic conditions arrested
    further degradation while aerobic incubation allowed continued

    metabolism. Essentially no 14C or 3H radioactivity was lost during
    incubation indicating stability of the aromatic ring system. The major
    metabolite was fenamiphos sulphoxide with some further thio-oxidation
    and hydrolysis observed under aerobic conditions.

         The effect of fenamiphos on soil microbial populations was
    studied by Houseworth and Tweedy (1972) using Indiana clay loam and
    Commerce silt loam soils. The soils were treated with 50 and 250 mg/kg
    of the pesticide and maintained at 50% field moisture capacity for 56
    days. At intervals, samples of soil were removed from each treatment
    and assayed for populations of bacteria, fungi and Actinomycetes.
    Fenamiphos had no significant effect on them under the conditions of
    the experiment.

         The photodecomposition of thin films of fenamiphos was
    investigated by Khasawinah and Sandie (1974). Thin films of dual
    labelled ethyl-1-14C, methylthio-3H fenamiphos were coated on glass
    plates and silica gel coated glass plates and exposed in the open air
    for about three weeks. Fenamiphos was rapidly oxidized to its
    sulphoxide and then to the sulphone. Some hydrolysis of the sulphone
    occurred after long intervals, especially on glass.

         The results of some studies in the USA of the persistence of
    fenamiphos and its oxidation products in various types of soil were
    available to the Meeting. They are reproduced in Table 7.

    In storage and processing

         The effect of alkali refining and steam deodorization on residues
    in cottonseed and soybean oils was studied in laboratory simulation
    experiments by Thornton (1973a) and Olson (1972b, 1974). In
    cottonseed, the two processes in combination removed 98.5% of the
    fenamiphos, 98.4% of the sulphoxide and 88% of the sulphone. Since the
    sulphone would constitute only a small proportion of a naturally
    occurring residue, the combined processes would remove nearly all the
    residue. In soybeans, the effects of the processes on sulphoxide
    residues was studied, as this is the main component of the residue
    after long post-treatment intervals. The simulated refining process
    removed 96% of the sulphoxide, and deodorization removed 38%. A
    hypothetical residue of 0.42 mg/kg should therefore be reduced to 0.01
    mg/kg by the two steps.

         The effect of citrus processing on residues of fenamiphos
    sulphoxide was investigated by Olson (1972a). Commercial citrus
    processing involves liming and drying of the chopped solids in the
    preparation of cattle feed. Fenamiphos sulphoxide, the main metabolite
    in crops, was resistant to the liming step but 39% of the residue was
    removed by drying. To prepare citrus oil, an aqueous emulsion is
    centrifuged vigorously. 99% of any fenamiphos sulphoxide present in
    the emulsion would be removed from the oil by this procedure.


    
    TABLE 7  Persistence of fenamiphos + sulphoxide + sulphone in various soils in the USA1

                                                                                                                                       

                        Residue, phenamiphos + sulphoxide + sulphone, mg/kg, after interval, days2

                             0                    30-40                80-100                   180-200                 360-400
    Soil            Range        Mean        Range       Mean       Range      Mean         Range       Mean        Range        Mean
                                                                                                                                       

    Silt loam       1.2-15       7.7         5.4-12      9.4        0.8-15     6.9          0.1-6.5     2.5         0.1-2.5      1.1

    Clay            1.0-1.7      1.3         3.7         3.7        1.5-2.7    2.1          0.6-1.3     1.0         0.6-0.7      0.7

    Sand muck       5.1-6.3      5.7         5.1-5.8     5.4        0.1        0.1          0.7-1.0     0.8         0.4-0.6      0.5

    Sand            5.5          5.5         0.3-0.6     0.5        0.1-0.2    0.2          0.06-0.07   0.07        0.03-0.04    0.04

    Sand clay       6.8-8.5      7.7         3.0-4.9     3.9        0.5-1.2    0.8          0.1         0.1         0.1          0.1

    Fox sand        4.3-9.2      6.7         6.8-8.0     7.4        3.1-3.2    3.1          1.0-1.3     1.1         0.9-1.0      0.9

    Peat            15-16.5      16          17-20       18         12.5-17    15           6.8-8.8     7.4         6.3-7.2      6.8

    Low humus       13-17        15          4.6-6.6     5.5        3.6-6.6    5.1          1.2-3.3     2.2         0.3-0.6      0.4
                                                                                                                                       

    1  Fenamiphos was added to soils at 10mg/kg level as granules or spray concentrate.

    2  Usually two or three analyses at each interval.
    


         Olson (1970a) studied the fate of residues on pineapple crowns.
    The fresh crowns were dipped in an aqueous emulsion of spraying
    concentrate containing 0.12% fenamiphos, and allowed to drain dry. The
    surface residue immediately after treatment amounted to about 30 mg
    per crown, of which about half could be removed by extracting with
    water. Seven days after treatment, aqueous extraction removed about
    one-third of the original residue. Surface extraction with benzene,
    however, removed virtually all the initial deposit (29 mg per crown)
    but only 27% (8 mg) after 7 days.

         Storage of broccoli, carrots, peanut kernels, pineapple fruit and
    potatoes at -18° to -23°C for two years showed no significant loss of
    fenamiphos, the sulphoxide or the sulphone (Anonymous, 1973).

         There was no significant loss of residues (parent + sulphoxide +
    sulphone) in field-treated potatoes or of fenamiphos from potatoes
    fortified in the laboratory when cooked at 100°C for 30 minutes in
    sealed jars (Thornton, 1972).

    METHODS OF RESIDUE ANALYSIS

         A specific gas-chromatographic procedure for the determination of
    residues of fenamiphos and sulphoxide and sulphone in various crops,
    animal tissues and milk is described by Thornton (1969, 1971a).
    Following initial extraction, the extract is oxidized with potassium
    permanganate to convert fenamiphos and its sulphoxide to the sulphone.
    The sulphone is then determined by gas chromatography with alkali
    flame ionisation detection. Recoveries from a variety of crops and
    animal tissues fortified with fenamiphos or its metabolites at the
    blending step were generally between 75 and 110%. Interference studies
    by Thornton (1971b, 1973b) and Olson (1970d, 1971b,c) have shown the
    method to be specific in the presence of other possible
    organophosphorus compounds. The limit of detection is about
    0.02 mg/kg.

         The determination of residues of fenamiphos and its metabolites
    in tobacco and tobacco smoke was successfully investigated by Olson
    (1971a) with the Thornton (1971a) method. This method should be
    suitable for regulatory purposes.

         The determination of fenamiphos residues in soil by thermionic
    emission gas chromatography is described by Olson (1970b). The soil
    sample is extracted in a Soxhlet apparatus, using a 1:1
    chloroform-methanol solvent mixture. The solvent is evaporated and the
    residue oxidized and chromatographed. Recoveries of fenamiphos and its
    metabolites were 80-107%. The sensitivity of the method is
    approximately 0.02 mg/kg. Olson (1970c) has also extended the
    procedure to a number of other organophosphorus pesticides.

    NATIONAL TOLERANCES REPORTED TO THE MEETING

         National tolerances reported to the Meeting are shown in Table 8.

    TABLE 8  National tolerances reported to the Meeting

                                                                            

                                                                   Safety
                                                    Tolerance      Interval
    Count        Crop                                 mg/kg        (days)
                                                                            

    Australia    Tomatoes, brassicas,
                 cucurbits, lettuce, citrus,
                 pineapples, grapes,
                 bananas, ginger                    No residue

    Spain        Tobacco sugarbeets, etc.
                 (industrial purpose),
                 bananas                                           60

    USA          Bananas, citrus                    0.1            180
                                                                            


    APPRAISAL

         Fenamiphos is a systemic nematicide which gives good control of
    root-knot cyst forming and free living nematodes. It is also effective
    against sucking insect pests and spider mites. It is formulated as 5%
    and 10% granules and as an emulsifiable concentrate (40%). Both
    formulations are recommended chiefly for treating bananas, pineapples,
    tomatoes, brassicas, eggplant, tobacco, groundnuts, citrus crops,
    ornamentals and pyrethrum. It is chiefly applied to the soil at sowing
    or planting. The general dose rate is 5-10 kg active ingredient/ha for
    broadcast application, but is reduced for band application. The
    emulsifiable concentrate is especially suitable for dip treatment of
    banana seedlings and for foliar spraying of pineapples. Fenamiphos is
    commercially used in Australia, USA, some Central and South American
    countries, Spain, the Cameroons and the Ivory Coast.

         Various investigations of the metabolism of fenamiphos in plants
    and soil demonstrate the rapid thio-oxidation of the parent compound
    to the sulphoxide and sulphone. In general the major part of the
    residue in crops and soil is the sulphoxide, followed by the sulphone.
    Both are relatively persistent. Both metabolites are detoxified by
    hydrolysis, usually followed by conjugation of the phenolic products
    as glycosides. Little or none of the parent fenamiphos seems to be
    present in most crops at harvest.

         Micro-organisms in soil do not seen to be affected by fenamiphos.
    The dissipation of residues in soil depends on the type of soil,
    increasing in the order peat < silt loam < clay = sand. Fenamiphos
    is only very slowly leached from soil.

         Following application in accordance with good agricultural
    practice, the maximum residue levels of fenamiphos including its
    sulphoxide and sulphone in Brussels sprouts, cotton seed, cabbage,
    carrots, cauliflower, grapefruit, lemons, limes, melons, oranges
    (pulp), peanut kernels, pineapples, soybeans (dried) and sugar beets
    are at or below 0.05 mg/kg. Higher residues are found in some other
    crops. Typical maximum residues are: grapes 0.1 ppm, lettuce 0.5 ppm,
    potatoes 1 ppm, strawberries 0.7 ppm, tomatoes 0.3 ppm and tobacco
    (green) 12 ppm, (cured) 140 ppm (fermented) 100 ppm. Data for
    fenamiphos residues in tobacco smoke are not available.

         Processing cottonseed or soybeans to oil removed 98-99% of the
    residues and processing citrus to cattle feed removed about 40%.
    Cooking potatoes had no significant effect. In a laboratory experiment
    approximately one third of the fenamiphos originally applied was
    extractable with water from the surface of the crowns of pineapples
    seven days after dipping in an aqueous emulsion containing 0.12%
    fenamiphos.

         Residues in eggs and tissues from hens fed for 14 days with 14C
    ring-labelled fenamiphos in feed at 0.65 ppm were below 0.005 mg/kg.
    Residues in milk and tissues of a dairy cow fed once with a dose
    corresponding to 27 ppm fenamiphos sulfoxide in the diet were below
    0.01 ppm.

         Specific gas-chromatographic procedures for the determination of
    residues of fenamiphos, its sulphoxide and sulphone in various crops,
    animal tissues, milk and soil have been elaborated. The initial
    extract is oxidized with permanganate to convert fenamiphos and its
    sulphoxide to the sulphone. The sulphone is determined with an alkali
    flame ionisation or flame photometric detector. Limits of detection
    are about 0.02 ppm, and recoveries higher than 75%. The methods should
    be suitable for regulatory purposes.

    RECOMMENDATIONS

         The following limits refer to fenamiphos including its sulphoxide
    and sulphone, expressed as fenamiphos.

    TOLERANCES

                                                           Tolerance
    Crop                                                    (mg/kg)

    Bananas, coffee beans (green and
     roasted, grapes, sweet potatoes                          0.1

    Broccoli, Brussels sprouts, cabbage,
    carrots, cauliflower, citrus fruits,
    cottonseed, melons, peanut kernels,
    pineapples, soybeans (dried), sugar beets                 0.05*

    * At or about the limit of determination.

    TEMPORARY TOLERANCES

                                                           Temporary
                                                           tolerance
    Crop                                                    (mg/kg)

    Potatoes, tomatoes                                       0.2

    FURTHER WORK OR INFORMATION

    REQUIRED (by 1977)

    1.   Further data on which to judge the residues in or on potatoes and
         tomatoes.

    2.   Adequate residue data on which to base recommendations for
         tolerances for other crops (e.g. beans, cucumbers, lettuce,
         peppers and strawberries).

    DESIRABLE

    1.   Brain cholinesterase and behavioural studies in animals exposed
         to low levels for extended periods.

    2.   Observations in man.

    3.   Additional studies on the potentiation effects with other
         organophosphorus pesticides.

    4.   Residue data for raw agricultural products moving in commerce.

    5.   Further residue data for different crops from supervised trials
         including data on rates and frequencies of application, soil,
         foliar or other treatment and pre-harvest intervals, especially
         for broccoli and tangerines.

    REFERENCES

    Anonymous. (1973) The effect of frozen storage at 0 to -10°F on
    Nemacur residues in peanut meat, broccoli, carrot roots, potatoes,
    pineapple fruit. Chemagro Report No. 36132, 36318, 36319, 36320,
    39094.

    Arnold, D., Keplinger M. and Fancher, O. (1971) Mutagenic study with
    Nemacur(R) (BAY 68138) Technical in albino mice. Report from
    Industrial BioTest Laboratories, Inc., submitted by Bayer AG.
    (Unpublished).

    Cherry, C., Urwin, C. and Newman, A. (1972) Pathology report of BAY
    68,138. Rat breeding study. Report from Huntingdon Research Centre,
    submitted by Bayer AG. (Unpublished).

    Cherry, C. and Newman, A. (1973) Pathology report of Bayer 68,138.
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    Church, D.D. (1971) Nemacur - leaching, runoff and water stability.
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    Coulston, F. and Wills, J.H. (1974) Summary of research of the
    Institute of Comparative and Human Toxicology, Albany Medical College,
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    Crawford, C., Anderson, R. and Nelson, D. (1970a) The skin and eye
    irritating properties of BAY 68,138 3 lb/gal S.C. to rabbits. Report
    from Chemagro Division of Baychem Corporation, submitted by Bayer AG.
    (Unpublished).

    Crawford, C., Anderson, R. and Nelson, D. (1970b) The acute inhalation
    toxicity of Nemacur(R) 15% granular to rats. Report from Chemagro
    Division of Baychem Corporation, submitted by Bayer AG. (Unpublished).

    Crawford, C, and Anderson, R. (1971) The skin and eye irritating
    properties of Bay 68138 technical to rabbits. Report from Chemagro
    Division of Baychem Corporation, submitted by Bayer AG. (Unpublished).

    Crawford, C. and Anderson, R. (1972a) The acute dermal toxicity of
    Nemacur(R) technical to rabbits. Report from Chemagro Division of
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    Crawford C. and Anderson, R. (1972b) The acute dermal toxicity of
    Nemacur(R) 3 lbs/gal. spray concentrate to rabbits. Report from
    Chemagro Division of Baychem Corporation, submitted by Bayer AG.
    (Unpublished).

    Crawford C. and Anderson, R. (1973a) The dermal toxicity of Nemacur(R)
    15% granules to rats. Report from Chemagro Division of Baychem
    Corporation, submitted by Bayer AG. (Unpublished).

    Crawford, C. and Anderson, R. (1973b) Comparative oral toxicity in
    rats of several impurities and a technical compound of Nemacur(R) with
    analytical grade Nemacur(R). Report from Chemagro Division of Baychem
    Corporation, submitted by Bayer AG. (Unpublished).

    Crawford C. and Anderson, R. (1973c) The eye and skin irritancy of
    Nemacur(R) 2 lb/gal spray concentrate to rabbits. Report submitted by
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    Crawford, C. and Anderson, R. (1974) The acute oral toxicity of two
    Nemacur(R) phenolic metabolites and MTMC to male and female rats.
    Report from Chemagro Division of Baychem Corporation, submitted by
    Bayer AG. (Unpublished).

    DuBois, K., Flynn, M. and Kinoshita, F. (1967) The acute toxicity and
    anticholinesterase action of Bayer 68138. Report from University of
    Chicago. (Unpublished).

    DuBois, K. and Flynn, M. (1968) The subacute parenteral toxicity of
    BAY 68138 to rats. Report from University of Chicago, submitted by
    Bayer AG. (Unpublished).

    DuBois, K. and Kinoshita, F. (1970) Acute oral and dermal toxicity of
    a granular formulation of BAY 68138. Report from University of
    Chicago, submitted by Bayer AG. (Unpublished).

    DuBois, K. and Kinoshita, F. (1971) The acute oral and inhalation
    toxicity of a Nemacur(R) (BAY 68138) formulation to rats. Report from
    University of Chicago submitted by Bayer AG. (Unpublished).

    Flint, D.R. (1973) The metabolism of Nemacur in pineapple. Chemagro
    Report No. 39 119.

    Flint, D.R., Church, D.D., Shaw, H.R. and Armour, J., II. (1971) The
    mobility and persistence of Nemacur in soil and water. Chemagro Report
    No. 29 974.

    Gronberg, R.R. (1969) The metabolic fate of
    ethyl-4-(methylthio)-m-tolyl isopropylphosphoramidate (BAY 68138),
    ethyl-4-(methylsulfinyl)-m-tolyl isopropylphosphoramidate (BAY 68138
    sulfoxide) and ethyl-4-(methylsulfonyl)-m-tolyl-isopropylphosphoramidate
    (BAY 68138 sulfone) in white rats. Report No. 26759 from Chemagro
    Division of Baychem Corporation, submitted by Bayer AG.
    (Unpublished).

    Gronberg, R.R., Flint, D.R. and Pither, K. (1974) The metabolic fate
    of Nemacur sulfoxide administered orally to a lactating dairy cow.
    Report No. 41104 from the Chemagro Division of Baychem. Corp.,
    submitted by Bayer AG. (Unpublished).

    Gronberg, R.R., Simmons, C.E. and Shaw, H.R., II. (1973) Residues of
    Nemacur in poultry eggs and tissue. Report No. 35995 from the Chemagro
    Division of Baychem Corporation, submitted by Bayer AG. (Unpublished).

    Houseworth, L.D., and Tweedy, B.G. (1972) Effect of Nemacur on
    microbial populations. Chemagro Report No. 34 990.

    Khasawinah, A.M. (1970) The fate of Nemacur in soil. Chemagro Report
    No. 28 796.

    Khasawinah, A.M. (1971) Metabolism of Nemacur in tobacco plants.
    Chemagro Report No. 29 142.

    Khasawinah, A.M. (1972a) Metabolism of Nemacur in snap beans grown in 
    closed glass chambers. Chemagro Report No. 34 992.

    Khasawinah, A.M. (1972b) The uptake and metabolism of Nemacur soil 
    residues by soybean plants. Chemagro Report No. 35012.

    Khasawinah, A.M. (1973a) Metabolism of Nemacur in carrots. Chemagro
    Report No. 36005.

    Khasawinah, A.M. (1973b) Metabolism of Nemacur in tomatoes. Chemagro
    Report No. 38501.

    Khasawinah, A.M. (1973c) The metabolism of Nemacur in cabbage.
    Chemagro Report No. 39120.

    Khasawinah, A.M. and Flint, D.R. (1972) Metabolism of Nemacur(R)
    [ethyl-4-(methylthio)-m-tolyl isopropylphosphoramidate] by rat liver
    microsomes in vitro. Report No. 34217 from Chemagro Division of
    Baychem Corporation, submitted by Bayer AG. (Unpublished).

    Khasawinah, A.M. and Sandie, F.E. (1974) Photodecomposition of thin
    films of Nemacur. Chemagro Report No. 39217.

    Kimmerle, G. (1970) Subchronic neurotoxicity studies on chickens.
    Report from the Institute for Toxicology, submitted by Bayer AG.
    (Unpublished).

    Kimmerle, G. (1971) Acute neurotoxicity studies on hens. Report from
    Institute for Toxicology, submitted by Bayer AG. (Unpublished).

    Kimmerle, G. and Solmecke, B. (1971a) BAY 68138 toxicological studies.
    Report from Institute for Toxicology, submitted by Bayer AG.
    (Unpublished).

    Kimmerle, G. and Solmecke, B. (1971b) Granular formulation. Acute
    dermal toxicity on rats. Report from the Institute for Toxicology,
    submitted by Bayer AG. (Unpublished).

    Kimmerle, G. (1972a) Antidotal experiments on rats. Report from the
    Institute for Toxicology, submitted by Bayer AG. (Unpublished).

    Kimmerle, G. (1972b) Acute inhalation toxicity study with Nemacur(R)
    active ingredient on rats. Report from the Institute for Toxicology,
    submitted by Bayer AG. (Unpublished).

    Kimmerle, G. (1972c) Acute toxicity of SRA-3886 in combination with
    S-276 and with E-154 to rats. Report from Institute for Toxicology,
    submitted by Bayer AG. (Unpublished).

    Ladd, R., Jenkins, D., Keplinger, M. and Fancher, O. (1971)
    Teratogenic study with Nemacur(R) technical in albino rabbits. Report
    from Industrial BioTest Laboratories, submitted by Bayer AG.
    (Unpublished).

    Löser, E. (1968a) Subchronic toxicological studies on dogs. Report
    from the Institute for Toxicology, Farbenfabriken Bayer AG.
    (Unpublished).

    Löser, E. (1968b) Subchronic toxicological studies on rats. Report
    from the Institute for Toxicology, submitted by Bayer AG.
    (Unpublished).

    Löser, E. (1969) Subchronic toxicological studies on dogs (3 month
    feeding test). Report from the Institute for Toxicology, submitted by
    Bayer AG. (Unpublished).

    Löser, E. (1970) Subchronic toxicological studies on dogs. Report from
    the Institute for Toxicology, submitted by Bayer AG. (Unpublished).

    Löser, E. and Kimmerle, G. (1971) Acute and subchronic toxicity of
    Nemacur(R), active ingredient. Pflanzenschutz-Nachr. Bayer,
    24(1):69-113.

    Löser, E. (1972a) Chronic toxicological studies on rats (2 year
    feeding experiment). Report from the Institute for Toxicology,
    submitted by Bayer AG.

    Löser, E. (1972b) Chronic toxicological studies on dogs (2 year
    feeding experiment). Report from the Institute for Toxicology,
    submitted by Bayer AG. (Unpublished)

    Löser, E. (1972c) Generation studies on rats. Report from the
    Institute for Toxicology, submitted by Bayer AG. (Unpublished).

    Mawdesley-Thomas, L. and Urwin, C. (1970a) Pathology report of BAY
    68138. Subchronic toxicological studies in rats. Report from
    Huntingdon Research Centre, submitted by Bayer AG. (Unpublished).

    Mawdesley-Thomas, L. and Urwin, C. (1970b) Pathology report of BAY
    68138. Subchronic toxicity tests in dogs. Report from the Huntingdon
    Research Centre, submitted by Bayer AG. (Unpublished).

    Olson, T.J. (1970a) Residues on the surface of fresh pineapple crowns
    treated with an aqueous emulsion of S.C. formulation of Nemacur.
    Chemagro Report No. 28014.

    Olson, T.J. (1970b) Determination of Nemacur residues in soil by
    thermionic emission gas chromatography. Chemagro Report No. 28731.

    Olson, T.J. (1970c) Determination of Dasanit, Guthion, Metasystox R,
    Nemacur and trichlorfon in soil by thermionic emission gas
    chromatography. Chemagro Report No. 27835.

    Olson, T.J. (1970d) An interference study for the determination of
    residues of Nemacur on pineapple. Chemagro Report No. 28723.

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    tobacco smoke. Chemagro Report No. 30448.

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    residues of Nemacur on cotton and tomatoes. Chemagro Report No. 30095.

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    method for bananas. Chemagro Report No. 31041.

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    Nemacur sulfoxide. Chemagro Report No. 34050.

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    residues of Nemacur sulfoxide. Chemagro Report No. 33461.

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    in cottonseed oil. Chemagro Report No. 40113.

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    carcinogenic study with Nemacur(R) (BAY 68138) in Swiss white mice.
    Report from Industrial BioTest Laboratories, submitted by Bayer AG.
    (Unpublished).

    Spicer, J. (1970) Pathology report of BAY 68138. Subchronic
    neurotoxicity tests on hens. Report from the Huntingdon Research
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    68138. Chronic toxicity study in dogs (administration in diet for 2
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    (Unpublished).

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    metabolites in plant and animal tissues. J. agr. Food Chem., 19
    (5):890-893.

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    for Nemacur and metabolites. Chemagro Report No. 25533.

    Thornton, J.S. (1972) Effect of cooking on residues of Nemacur in
    potatoes. Chemagro Report No. 35314.

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    residues of Nemacur and metabolites in cottonseed oil. Chemagro Report
    No. 35345.

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    No. 36 142.

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    from Institute for Toxicology, submitted by Bayer AG. (Unpublished).

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    from Institute for Toxicology, submitted by Bayer AG. (Unpublished).

    Thyssen. (1974c) 4-methyl-mercapto-m-Kresol, Akute Toxizitat bei
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    (Unpublished).

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    Ratten. Report from Institute for Toxicology, submitted by Bayer AG.
    (Unpublished).

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    AG. (Unpublished).

    Tweedy, B.G. and Houseworth, L.D. (1974) Leaching of "aged" Nemacur
    residues in sandy loam soil. Chemagro Report No. 40 506.

    Waggoner, T.B. (1972) Metabolism of Nemacur [ethyl
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    of two metabolites in plants. J. agr. Food Chem., 20(1):157-160.
    


    See Also:
       Toxicological Abbreviations
       Fenamiphos (ICSC)
       Fenamiphos (Pesticide residues in food: 1977 evaluations)
       Fenamiphos (Pesticide residues in food: 1978 evaluations)
       Fenamiphos (Pesticide residues in food: 1980 evaluations)
       Fenamiphos (Pesticide residues in food: 1985 evaluations Part II Toxicology)
       Fenamiphos (Pesticide residues in food: 1987 evaluations Part II Toxicology)
       Fenamiphos (Pesticide residues in food: 1997 evaluations Part II Toxicological & Environmental)
       Fenamiphos (JMPR Evaluations 2002 Part II Toxicological)