WHO/FOOD ADD/71.42



    Issued jointly by FAO and WHO

    The content of this document is the result of the deliberations of the
    Joint Meeting of the FAO Working Party of Experts and the WHO Expert
    Group on Pesticide Residues, which met in Rome, 9-16 November, 1970.



    Rome, 1971



    Diazinon was evaluated at the Joint Meeting in 1965, 1966, 1967 and
    1968. Since the previous evaluation (FAO/WHO, 1968), some new
    experimental work has been reported on this compound. This new work is
    presented and discussed in the following monograph addendum.

    Information relating to the use, and to the occurrence of residues, of
    the pesticide has been freshly reviewed, and that part of this
    addendum headed RESIDUES IN FOOD AND THEIR EVALUATION is intended to
    replace the contests of previous monographs under this heading.


    Stabilization of diazinon formulations appear to have eliminated toxic
    condensation products of diethylphosphoric and diethylphosphorothioic
    acids and, thereby, to have reduced the overall mammalian toxicity
    (Geigy, 1969).



    Absorption and distribution

    Following daily oral administration of diazinon to two rats for ten
    days at a daily dose of 0.02 mg/kg body-weight, residue levels of less
    than 1 percent of the totally applied dose were found one day after
    cessation of treatment. Of the tissues examined, muscle (0.77 percent
    of the total dose applied), small intestine (0.65 percent),
    colon-caecum (0.76 percent), stomach-oesophagus (0.25 percent), fat
    (0.23 percent) and liver (0.16 percent) had the highest values six
    hours after the last application. This study precludes the
    accumulation of diazinon in mammalian tissue (Mücke et al., 1970).


    Further investigations in the rat were carried out by Mücke et al.,
    (1970) and these studies again confirmed that diazinon and its
    metabolites are rapidly excreted mainly in the urine. The studies
    indicated that no opening of the pyrimidine ring with subsequent
    oxidation of the fragments of CO2 takes place. From 95 percent (in
    females) to 98 percent (in males) of an oral dose of diazinon was
    excreted in 168 hours, with the major quantity present in urine (69
    percent in females and 80 percent in males) and faeces (24 percent in
    females and 16 percent in males). The material was present in urine
    and faeces as three derivatives of the pyrimidyl moiety and one polar
    unidentified fraction, presumably containing several components.

    The distribution and the excretion of 32P-labelled insecticide was
    also followed in the dog (Millar, 1963) and in the guinea pig
    (Kaplanis et al., 1962). Considerable breakdown of diazinon in these
    species was confirmed. In the case of the guinea pig, the elimination
    of the radioactivity ceased within 7 days, by which time more than 87
    percent of the oral dose left the body with the urine.


    Organophosphorus insecticides are degraded in animals by cleavage of
    phosphorus ester linkages. In the case of phosphorothioates, the
    common routes of metabolism are the ones leading to the production of
    dialkyl phosphorothioic acids and the other forming, after
    denitrification, dialkyl phosphoric acids. It has long been assumed
    that these metabolites were produced by hydrolytic action of

    It is suggested that many of the so-called phosphatase products or
    hydrolysis products may actually be oxidative metabolites.

    Results of in vitro studies using rat liver microsomes and reduced
    pyridine nucleotide cofactors in the presence of oxygen indicate that
    diazinon is oxidatively activated to the oxygen analogue diazoxon and
    degraded by hydrolysis to diethylphosphorothioic acid (Nakatsugawa et
    al., 1969).

    Mücke et al. (1970), investigating the in vivo degradation of
    diazinon in the rat, characterized urinary oxidative metabolites of
    the pyrimidyl moiety following hydrolysis as *(see below) and the
    **(see below) as well as the major unchanged enol,

    Thin layer chromatographic analysis of the urine demonstrated the
    presence of four metabolite fractions. Fractions 1, 2 and 3 were found
    to be homogeneous, whereas fraction 4 contained a series of very polar
    substances. Spectroscopic investigations of these metabolites revealed
    that each contained the same heterocyclic moiety. This ring system has
    been identified as:


    Hydrolysis of the ester bond yielding
    2-isopropyl-4-methyl-6-hydroxypyrimidine and oxidation at the primary
    and tertiary carbon atom of the isopropyl side chain were found as the
    main degradative mechanisms. The structure of the main metabolites was

    confirmed by independent synthesis, and the inhibitory activities on
    acetyl cholinesterase were determined. The structure of the
    metabolites and the metabolic pathway of the pyrimidine moiety are
    shown in Figure 1.

    * 2-(1-hydroxy-2-propyl)-4-methyl-6-hydroxypyrimidine

    ** 2-(2-hydroxy-2-propyl)-4-methyl-6-hydroxypyrimidine

    The actual sequence of the degradation reactions was determined by
    following the fate of 14C-labelled metabolites after intravenous
    application. Metabolite 1 resulted in the same pattern of metabolites
    as diazinon itself. Metabolite 2 was excreted mainly unchanged and
    metabolite 3 was excreted in a completely unchanged form.

    Hastie (1963) reviewed available data on the metabolism and
    elimination of diazinon from animals and animal tissues. When orally
    administered, diazinon is degraded by the digestive enzymes before the
    lipid-soluble material can reach the fat depots. The more circuitous
    route involved following dermal application allows a certain amount of
    diazinon to bypass the sites of degradation, thereby reaching the fat
    depots unchanged. Reabsorption into the digestive tract from these
    depots is a somewhat delayed process.


    Special studies on teratogenicity

    Hamster and rabbit

    An examination of the teratogenic potential of diazinon was performed
    using Golden Syrian hamsters and New Zealand white rabbits (Robens,
    1969). Oral administration of diazinon in maize oil at a dose of 0.125
    mg/kg body-weight on day 6, 7 and 8 of gestation and at 2.25 mg/kg
    body-weight on day 7 or 8 produced no terata in the hamster.
    Administration of diazinon to rabbits daily from day 5 to 15 of
    gestation at 7 or 30 mg/kg body-weight per day induced no terata or
    dose-related embryotoxic effects.

    Special studies on acute toxicity of metabolites

    LD50 values following acute oral administration to rats are available
    for two diazinon metabolites:

    2-isopropyl-4-methyl-6-hydroxypyrimidine: 2 700 mg/kg body-weight

    5 000 mg/kg body-weight
    (Mücke et al., 1970).

    FIGURE 1

    Results in Table I indicate a complete loss of acetyl cholinesterase
    inhibitory power. The table also indicates that a drastic reduction in
    the acute toxicity of the insecticide had occurred during metabolism
    (Mücke et al., 1970).


    Properties of the main metabolites
    Compound        Acute LD50         Inhibition of
                                         AChE ID50

    Diazinon        approx. 250 mg/kg    2.7 × 10-5M

    Metabolite 1    approx. 2 700 mg/kg  10-2M

    Metabolite 2            5 000 mg/kg  10-2M

    Recent investigations by Mücke et al. (1970), have shown that
    2-isopropyl-4-methyl-pyrimidin-6-ol is of low toxicity, having an
    acute oral LD50 of approximately 2 700 mg/kg in the rat, and that
    there is no detectable anticholinesterase activity. These findings
    provide an answer to the doubts expressed by Ralls et al. (1966),
    concerning the toxicity of 2-isopropyl-4-methyl-pyrimidin-6-ol.

    No information is available on the toxicity of the metabolite found
    after treatment of kale with diazinon (see "FATE OF RESIDUES. In

    Acute toxicity

                   Acute toxicity to the rat
                   (various workers)

    Animal         Route       LD50             Reference

    Rat            oral        250 (male)       Gaines, 1969

    Rat            oral        285 (female)     Gaines, 1969

    Rat            oral        466              Boyd & Carsky, 1969

    Rat            oral        293-408 (male)   Edson & Noakes, 1960

    Rat            dermal      900 (male)       Gaines, 1969

    TABLE II (cont'd)
                   Acute toxicity to the rat
                   (various workers)

    Animal         Route       LD50             Reference
    Rat            dermal      455 (female)     Gaines, 1969

    Acute toxicity of diazinon to rats is summarized in Table II.

    Differences in LD50 values expressed over the past few years may be
    due to the presence of impurities contaminating early diazinon
    samples. It has been shown that, under certain conditions,
    combinations of molecules of diethyl phosphorothioic acid and
    diethylphosphoric acid can condense to produce
    tetraethylpyrophosphoric esters, which may be extremely toxic.
    Stabilization of diazinon formulations appear to have eliminated some
    of these condensation products and reduced the acute LD50 (Geigy,

    As has been demonstrated with other pesticides, the acute LD50 to
    rats increased as the protein level in the diet increased or decreased
    from an optimal level. Raising the protein content from 29 percent to
    81 percent, or lowering the protein content to 4 percent, increased
    the toxicity approximately twofold (Boyd et al., 1969).

    Short-term studies

    Dog and pig

    Groups of pigs (three male and three female) and dogs (three male and
    three female) were orally administered diazinon by capsule daily for
    periods up to eight months at doses of 0, 1.25, 2.5, 5 and 10 mg/kg
    body-weight/day to pigs and 0, 2.5, 5, 10 and 20 mg/kg body-weight/day
    to dogs (Earl et al., 1970). In pigs, mortality and cholinergic signs
    of poisoning were evident at 2.5 mg/kg/day and above. Although
    significantly increased myeloid/erythroid (ME) ratios were observed,
    no aplastic anaemia was evident. In dogs, mortality and cholinergic
    signs of poisoning were evident above 10 mg/kg, with significantly
    increased ME ratios observed in dogs dying at 20 mg/kg. No evidence of
    aplastic anaemia was observed in dogs and pigs.

    Long-term studies

    No new information available.


    It has been demonstrated that diazinon is oxidized in vitro to
    diazoxon and further to diethylphosphorothioic acid. Farther
    degradation has been shown to occur in vivo with the urinary
    metabolites, which are substantially less toxic than the parent
    compound. Distribution of diazinon in the body was relatively low,
    with no accumulation in tissues or organs noted. Excretion in urine
    and faeces was fairly rapid. No signs of blood dyscrasias were evident
    in studies with dogs and pigs. No teratogenic or embryotoxic effects
    were observed in hamsters and rabbits.

    Stabilization of diazinon formulations have been reported to have
    eliminated potential condensation products of diethylphosphoric acid
    and diethylphosphorothioic acid. Information on the long-term toxicity
    effects of diazinon is still inadequate. No information is available
    on residuous anticholinesterase metabolites which may occur in plants.


    Level causing no toxicological effects

    Rat:        0.1 mg/kg body-weight/day

    Dog:        0.02 mg/kg body-weight/day

    Monkey:     0.05 mg/kg body-weight/day

    Man:        0.02 mg/kg body-weight/day


    0 = 0.002 mg/kg body-weight



    Pre-harvest treatments

    Diazinon is a broad spectrum insecticide which has found many
    applications, including control of:

    (a)   pests of field crops, orchards and pastures;

    (b)   animal ectoparasites;

    (c)   soil-inhabiting insects;

    (d)   industrial, public health and domestic pests.

    Numerous formulations, including emulsifiable concentrates, wettable
    powders, dusts and granules, are available. Foliar pests are normally
    controlled by application in spray form, but effective control of rice
    stem borer and some leaf hoppers has been obtained through application
    of granules. Animals are normally treated by dipping, spraying,
    jetting or dusting.

    In the United States, diazinon is registered for application to more
    than 60 food or feed crops including most fruits, vegetables and
    forages. Use on corn (maize) for control of corn root worm and corn
    ear worm and to alfalfa (lucerne) for control of alfalfa weevil are
    major applications. There is an increasing use on rice.

    Dipping, jetting or spraying of sheep for protection against sheep
    blowfly are major uses in Australia, New Zealand, South Africa and
    South America. Due to its solubility in wool grease, the material can
    remain on the sheep in a stable state for several weeks and thus
    provide effective protection against parasite attack. Dermal
    applications to sheep, cattle and goats are also used for control of
    lice, ticks, horn flies and certain other insects.

    Table III summarizes typical dosages and pre-harvest periods for the
    various crop categories. Diazinon has been found effective in
    controlling over 100 species of food crop pests such as mites, aphids,
    thrips, maggots, fruit flies, worms, beetles, grasshoppers, leaf
    miners, etc. Seed furrow soil treatments are used for several root
    vegetable crops.

    Diazinon dosages and pre-harvest periods

    Crop                Actual dosage                      Pre-harvest
                                                           period (days)

    Tree fruits         0.5 lb/100 gal (full coverage)     10-20

    loganberries)       1.0 lb/acre (full coverage)        7

    Citrus              0.5 lb/100 gal (full coverage)     7-21

    Leafy vegetables    0.5-1.0 lb/acre                    5-21

    Root vegetables     0.5-1.2 lb/acre                    10

    Others              0.25-1.0 lb acre                   0-7

    TABLE III (cont'd)
    Diazinon dosages and pre-harvest periods

    Crop                Actual dosage                      Pre-harvest
                                                           period (days)
    Forages & hays      0-5-1.0 lb/acre                    No grazing
                                                           4-10 days
                                                           before cutting

    Cattle & sheep      1.0-2.3 gal of 0.30-0.5%           (14
                        spray per animal                   pre-slaughter

    Post-harvest treatments

    There is no commercial post-harvest use of diazinon on crops.

    Other uses

    Diazinon is recommended for fly control in dairy barns and other farm
    buildings as well as in food processing plants; however, this is
    becoming less important because of resistance developed by flies. It
    is also used in households to control carpet beetles and clothes
    moths, in home gardens and in buildings to combat ants, cockroaches,
    fireants, etc. Control of cockroaches is an important field of use.


    Residues of diazinon on or in plants, in animal tissues, or even in
    the soil, are not highly persistent. In many countries and on over
    sixty crops, residues have been determined at various time intervals
    after applications of varying amounts of diazinon. For example, in the
    controlled experiments with apples in the U.S.A., 16 varieties were
    treated in 15 states using ´ to 1 lb/100 gal (i.e., full coverage
    sprays) on various spray schedules and in combination with other
    pesticides and fungicides.

    A summary of the numerous data (Geigy, 1956-67) obtained from the
    rates of application shown in Table III is given in Table IV.

        TABLE IV

    Diazinon residues at different application rates


                        Typical                     Residues at
    Crops               initial        Pre-harvest  pre-harvest      Estimated
                        residues       period       period           half-life
                        (ppm)          (days)       indicated (ppm)  (days)

    Tree fruits

    Apples              0.6-0.8        14           0.1-0.4          5
    Pears               0.6-0.7        14           0.1-0.3          5
    Cherries            3-7            10           0.1-0.3          3
    Peaches             2-6            20           0.1-0.6          3-6
    Apricots            1-4            10           0.1              2
    Nectarines          1-6            10           0.2              3-4
    Plums & prunes      2-4            10           <0.1-0.2         2
    Figs                0.5            10           <0.1             3


    Almonds   )
    Filberts  )         0.1 (nuts)     10           <0.1 (nuts)
    Walnuts   )                        60           <0.1 (kernels)


    Oranges             3-5            21           0.1-0.4          4
    Lemons              4.0            21           0.6-0.7          6-7
    Grapefruit          0.3            7            0.1-0.2          7

    Caneberries and small fruit

    Strawberries        0.9-1.4        5            0.2-0.4          2-4
    Grapes              1-8            18           <0.1-0.3         3
    Cranberries         9              7            <0.1             1
    Blueberries         1-4            7            <0.1-0.3         1-2
    Blackberries  )
    Boysenberries )     1-5            7            <0.1-0.3         2
    Loganberries  )
    Raspberries   )

    TABLE IV (cont'd)

    Diazinon residues at different application rates

                        Typical                     Residues at
    Crops               initial        Pre-harvest  pre-harvest      Estimated
                        residues       period       period           half-life
                        (ppm)          (days)       indicated (ppm)  (days)
    Leafy vegetables

    Cabbage             1-2.5          7            <0.1-0.7         4-6
    Celery              2-9            10           <0.1-0.7         2
    Cauliflower         1              5            0.4-0.5          7
    Broccoli            1-2            5            <0.1-0.5         3
    Lettuce             6-17           10           0.3-0.5          1-2
    Spinach             5-12           10           <0.1-0.2         2
    Endive              3-18           10           0.1              2
    Collards            3              12           <0.1             2
    Kale                10-24          12           0.1-0.2          1
    Parsley             1-6            12           0.1-3.0          2
    Swiss chard         2              12           <0.1             2
    Turnip greens       4-15           12           <0.1             2
    Brussels sprouts    0.2            10           <0.1

    Root vegetables (foliar application)

    Beets               <0.1           0
    Onions              7-13 (green)   10 (green)   0.4-0.6 (green)  2
                        2-3  (dry)     10 (dry)     <0.1-0.3 (dry)   2
    Carrots             1-2            10           0.1-0.3          2-3
    Carrots (soil
    application)                       120          0.1
    Parsnips            0.7            10           0.3              6
    Radishes            <0.1-0.4       10           <0.1             4
    Turnips             0.5            10           0.4-0.5          21

    Vegetables (others)

    Peppers             0.6-0.8        5            <0.1-0.2         2-3
    Cucumbers           1.0-2.5        7            <0.1             2
    Green beans         1-2            7            <0.1             2
    Lima beans          0.2-1.0        7            <0.1-0.2         2
    Squash              0.1-0.2        3            <0.1-0.2         2
    Maize (ears only)   <0.1           0            <0.1             -
    Peas (plus pod)     <0.1           0            <0.1             -


    Tomatoes            0.1-0.4        3            <0.1-0.2         2
    Melons              0.1-0.7        3            <0.1-0.2         2-3
    Olives              1-6            75           <0.2-0.6         ca 25

    TABLE IV (cont'd)

    Diazinon residues at different application rates

                        Typical                     Residues at
    Crops               initial        Pre-harvest  pre-harvest      Estimated
                        residues       period       period           half-life
                        (ppm)          (days)       indicated (ppm)  (days)

    Hops (cones)        3-11           14           0.1-0.3          3
    Sorghum (grain)     0.5            7            <0.1             2
    Cotton (seed)       0.1-0.2        7            <0.1
    Safflower (seed)    <0.1
    Sunflower                          80           0.1-0.2
    Sugarcane (stems)   <0.1           7            <0.1
    Tea                                7            <0.1 (manufactured)
    Coffee              1              7            0.1 (green beans)

    Cereal crops
    Wheat                              13           <0.1 (grain)


    Lamb (fat)          1-3            14           0.1-0.75         5
    Beef (fat)          1-3            14           <0.1-0.2         3


                   Pre-grazing  Cutting       Initial     Residue     Half
                   interval     time          residue     at          life
                   (days)       (days)        in forage   cutting     (days)
                                              (ppm)       (ppm)

    Alfalfa        0            7             12-24       0.2-0.5     2
    Clover         0            7             4-14        1.0-4.0     2-3
     grass         0            21            9           4.0-7.2     2-3
                                30 (oil
                                formulation)  54
    Pea/bean       0            4             5-10        2.0-5.0     2
    Maize          0            0             12-21       -           2
    General Comments

    In animals

    Reports from numerous trials indicate that residues of diazinon in
    subcutaneous fatty tissues of sheep and cattle treated for parasite
    control do not exceed 0.75 ppm one day after treatment. The residue
    levels in internal fat, however, may be higher. Average residue levels
    decline rapidly following treatment, but fat samples from individual
    animals may exceed 0.75 ppm for 14 days. Hastie (1965) showed that
    standard treatment procedures resulted in residues in sheep one day
    after treatment which were in excess of 1 ppm in the fat. After three
    days, residue levels had declined to 0.3-0.5 ppm. Claborn et al.
    (1963) showed that cattle sprayed with diazinon contained residues in
    omental fat six days after treatment, but residues were not detectable
    at 14 days.

    Residues of diazinon in animal fat may be influenced by the condition
    of the treated animal due to the dilution factor brought about by the
    total amount of fat present. Application rates also affect the residue

    In plants

    Residue levels in various crops have been reviewed by Bartsch (1970).
    Residue analyses of pip fruit have indicated that 90 percent of
    residues are in the peel of ripe fruit and only 2-4 percent in the
    pulp. No residues at all were detected in the pulp and juice of citrus
    fruits, since the peel serves as a barrier (Gunther et al., 1958).

    Residues present in any crop are dependent upon application rates,
    cultural practices and type of formulation used. Residues have
    generally been more persistent in glasshouse crops than in field crops
    (Bartsch, 1970). Granular formulations have given more variable
    residue levels in treated crops than have liquids applied as sprays.
    However, studies have indicated that residue levels are higher overall
    after crop treatment with emulsions rather than granules (Maier-Bode,

    After crop application of emulsions or granules, practically no
    residues have been detected in tubers (potatoes, sweet potatoes and
    yams) or in grain (rice and wheat). Residues in seeds of cotton,
    sunflower and safflower contain only little diazinon in contrast to
    the respective oil products.

    Immediately after treatment of forage crops, residues may reach 150
    ppm. Residue levels fall very rapidly, due in part to growth of the
    forage plants, and within a period of 1-2 days are below the current
    tolerances of 60 ppm for grass and 40 ppm for alfalfa (in the U.S.A.)

    Due to the solubility of diazinon in lipids, high residues may be
    found in olive oil, but they are below the accepted tolerance levels
    of 2 ppm in Italy and 1 ppm in U.S.A., 7-8 weeks after treatment.

    Carrots have been examined with particular care on account of their
    dietary significance, bearing in mind that they are often eaten
    uncooked, and because of their biochemical properties. Residue figures
    vary widely, depending on timing of application, formulation and
    method of application. All trial data reviewed by Bartsch (1970)
    indicated that unless harvest is carried out within 60 days of last
    treatment (soil-application), the residue level is below 0.5 ppm in
    all cases.


    In animals

    Investigations on the metabolic fate of diazinon in mammals were
    initiated mainly by the widespread use of the product as an
    ectoparasiticide in ruminants. Residue studies in fat and milk of cows
    (Bourne and Arthur, 1967; Claborn et al., 1963; Derbyshire and Murphy,
    1962; Matthysse and Lisk, 1968) and of sheep (Harrison and Hastie,
    1965; Matthysse et al., 1968) were carried out after the insecticide
    had been applied regularly by spraying and dipping or by feeding the
    animals on pasture treated with the insecticide. Only small amounts
    of diazinon residues have been found in fat and milk, whereas the
    other tissues were free of the insecticide. In two early studies in
    the cow (Robbins et al., 1957) and in the goat (Vigne et al., 1957),
    the rapid and complete elimination of the 32P-labelled insecticide
    in urine, faeces, blood and milk was shown, demonstrating urine as the
    main route of excretion.

    Rai and Roan (1959) found no residues of diazinon in the milk of dairy
    animals given daily oral doses of diazinon at the rates of 1.06, 5.30
    and 10.60 mg/kg of body-weight over a three-week feeding period. These
    administration rates are calculated to be 100, 500 and 1 000 ppm on
    the basis of the grain fed, or 51, 290 and 500 ppm on the basis of hay
    consumed. Steers treated with 165 and 825 ppm in daily oral doses
    calculated on the basis of grain fed showed traces of diazinon in
    blood, urine, muscle, liver and brain. Only in fat was a significant
    residue found, being 0.23 ppm at the maximum feeding level. These
    results were obtained by the use of three methods of analysis.

    In plants

    Practical residue determination on many occasions has shown that
    diazinon does not persist long as a residue on most food crops. It
    appears that the movement or metabolism of diazinon depends upon the
    plant species (Coffin and McKinley, 1964; Ralls et al., 1966; Gunner
    et al., 1966).

    Diazinon is passed through bean plants unchanged, with rapid
    translocation and emergence in bean root exudates after application of
    diazinon to aerial portion of the plant (Gunner et al., 1966). Sugar
    beet seedlings absorb diazinon applied to the soil (Onsager and Rusk,
    1967) and is translocated in quantities to render the plant

    insecticidal. This is contrary to earlier observations (Gunner, 1966),
    where it was found that diazinon was absorbed by beans but not
    translocated in toxic amounts.

    Analysis of alfalfa (lucerne) indicated that diazinon was absorbed 
    from treated soil into the plant (Nelson and Hamilton, 1970). No 
    metabolites of diazinon were found in the alfalfa, and diazinon was 
    expired by the plants. These findings substantiate the results 
    obtained by Gunner et al. (1966) with beans.

    The metabolism of diazinon in plants has been shown to involve
    hydrolysis of the phosphorus primidylester bond and subsequent
    metabolism of the 2-isopropyl-4-methyl-6-hydroxypyrimidine to carbon
    dioxide. Small amounts of diazoxon have at times been detected in
    field-grown crops (Gomaa et al., 1969). The fact that diazoxon levels
    are very low, if present at all, indicates oxidation is very minor or
    that the oxon is hydrolysed as rapidly as it is found. Margot and
    Gysin (1957) indicated loss of insecticidal activity on plants caused
    by evaporation of diazinon and through hydrolysis. No metabolites of
    diazinon were found.

    Coffin and McKinley (1964) reported on the metabolism and persistence
    of diazinon on field-sprayed lettuce. Diazinon residues decreased from
    8.1 ppm to 0.3 ppm from four hours to seven days after spraying, and
    detectable quantities of diazinon were present at 10 and 14 days. No
    significant amount of diazoxon or other metabolites were found by the
    paper chromatographic detection system.

    Grasses and grains grown for forage which had been treated with
    diazinon were analysed by the sulphide procedure. Maier-Bode (1963)
    found diminution of residues occurred only in the uncut grasses. After
    cutting and while drying to hay, little of the diazinon was lost.

    Ralls et al. (1966), studied the fate of 35S-labelled diazinon on
    field-grown crops and found a rapid decrease in diazinon residues. The
    metabolite identified from field samples was diazoxon. Three
    thin-layer chromatographic systems showed the presence of this
    metabolite on spinach at 0.005 to 0.01 ppm five days after spraying.
    Paper chromatography of snap bean extracts harvested seven days after
    treatment showed an increase in a cholinesterase-inhibiting compound
    with an Rf value corresponding to diazoxon.

    Additional studies in the field revealed residue levels of diazinon
    (I), diazoxon (II) and 2-isopropyl-4-methylpyrimidin-6-ol (III) made
    by Ralls et al. (1967), using diazinon-32p. A spinach sample
    analysed one hour after spraying contained 31.7 ppm (I), 1.5 ppm (II)
    and 2.5 ppm (III). Analysis of a four-day sample gave 1.8 ppm (I),
    0.34 ppm (II) and 2.5 ppm (III). Although diazinon and its oxygen
    analogue dissipated rapidly, compound (III), the result of further
    hydrolysis of diazoxon persisted at the same level. The mammalian
    toxicity of this persistent compound was at the time not known.
    Similar experiments with snap bean and tomato plants showed the same

    rapid disappearance of diazinon and diazoxon to levels greatly below
    0.1 ppm after four days. Less than 0.1 ppm of compound (III) was found
    in all four-day samples.

    Refined analytical techniques were used by Eberle and Novak (1969), to
    further investigate the fate of diazinon in plants. The only
    cholinesterase-inhibiting metabolite detectable at any time after
    diazinon application was diazoxon. The maximum levels of diazoxon
    found in apples and olive oil were 0.004 ppm and 0.007 ppm,
    respectively. At harvest, fruit and vegetables in all instances
    contained less than 0.002 ppm diazoxon.

    The appearance and subsequent disappearance of traces of diazoxon in
    the crops examined indicate that diazinon is oxidized in plants to
    diazoxon which is, in turn, rapidly altered to
    noncholinesterase-inhibiting products. All samples were analysed for
    monothiotetraethylpyrophosphate (S-TEPP), but no residues could be
    detected at the limit of 0.002 ppm. These results are at variance with
    the findings of Melchiorri et al. (1964), and Siesto et al. (1964),
    who earlier reported evidence of the formation of S-TEPP and TEPP. The
    investigations of Eberle and Novak do, however, support the findings
    of Ralls et al. (1966), in that the only cholinesterase-inhibiting
    metabolite detectable at any time after diazinon application is

    The levels of diazinon and diazoxon reported by Eberle and Novak are
    summarized in Table V.

        TABLE V

    Residues of diazinon and diazoxon on vegetables and fruit


    Application rate    Crop             Days after     Residues found (ppm)
    (g ai/100 l)                         last           diazinon    diazoxon

    40 (3 treatments)   golden apples    0              2.8         <0.002
                                         7              0.6         0.004
                                         21             0.3         0.002
                                         63 (harvest)   0.05        <0.002

    40 (3 treatments)   Jonathan         0              1.3         0.002
                          apples         28             0.2         <0.002
                                         70 (harvest)   0.1         <0.002

    50 (1 treatment)    pears            49             0.01        <0.002
    50 (2 treatments)                    35             0.01        0.003
    50 (3 treatments)                    21             0.02        <0.002
    50 (4 treatments)                    10             0.12        0.003

    TABLE V (cont'd)

    Residues of diazinon and diazoxon on vegetables and fruit


    Application rate    Crop             Days after     Residues found (ppm)
    (g ai/100 l)                         last           diazinon    diazoxon

    25 (2 treatments)   Langstieler      7              0.2         <0.002
                          cherries       28 (harvest)   0.02        <0.002

    25 (2 treatments)   Schauenburger    7              0.4         <0.002
                          cherries       28 (harvest)   0.02        <0.002

    4 (2 treatments)    Flakeer          29             1.3
                          carrots        80 (harvest)   0.2         <0.002

    4 (2 treatments)    Guérande         29             2.2
                          carrots        90 (harvest)   0.2         <0.002

       1 treatment      onions           125 (harvest)  0.05        <0.002

    10 (1 treatment)    radish           36 (harvest)   <0.02       <0.002

    25                  Milan cabbage    0              27
                                         7              1.7
                                         21             0.05
                                         63 (harvest)   <0.02       <0.002

    25                  Blanc cabbage    0              12.5
                                         7              1.1
                                         63 (harvest    <0.02       <0.002
    In contrast to the findings of other workers, a further alteration
    product, hydroxysiazinon, has been reported by Pardue et al. (1970).
    This previously unidentified compound was detected during a study of
    diazinon field-sprayed kale samples by a technique of enzyme
    inhibition thin layer chromatography of the extracts previously
    oxidized by bromine water.

    The levels of hydroxydiazinon found in kale in comparison with
    diazinon and diazoxon are indicated in Table VI.


    Residues found by GLC in diazinon-treated kale


                                        Days after application

                                  2         7         11        15

    Diazinon (ppm)                8.8       2.9       2.0       1.6

    Diazoxon (Ppm)                0.004     0.007     0.002     0.002

    Alteration product of
    diazinon1 (ppm)               0.18      0.05      0.03      0.03

    1  Later identified as hydroxydiazinon. Quantitated using the compound
       prepared by UV-irradiation of diazinon.
        Pardue et al. (1970) have not offered any possible explanation for the
    presence of hydroxydiazinon. Many of the cruciferous crops have waxy
    cuticles which would have a tendency to hold diazinon. The effect of
    UV-irradiation on diazinon could then possibly cause alteration to

    In soil

    Literature on diazinon residues in soils has been mainly confined to
    nonflooded conditions (Getzin and Rosefield, 1966; Getzin, 1967;
    Gunner et al., 1966). Getzin (1967) reported that greater amounts of
    the hydrolysis product were recovered from soil fumigated with
    propylene oxide than from nonfumigated soil. Conversely, little 14CO2
    was released from the fumigated soil treated with 14C-labelled
    diazinon, while large amounts were released from nonfumigated soil. He
    also suggested that the initial step in the degradation of diazinon in
    nonflooded soils is hydrolysis at the heterocyclic phosphate bond
    (phosphorus-oxygen-pyrimidine bond), followed by disruption of the
    pyrimidine ring and the subsequent release of 14CO2. Soil
    microflora appeared to play a major role in the of the degradation of
    the parent molecule. Trela et al. (1968) recently observed that the
    degradation of diazinon into pyrimidine and phosphorothioate
    derivatives was greatly stimulated in the presence of microorganisms
    isolated from diazinon-treated soil.

    The degradation of diazinon in submerged neutral or alkaline soil
    showed that diazinon disappeared at a faster rate from nonsterilized
    soils than from sterilized soils (Sethunathan and MacRae, 1969), thus
    indicating the participation of soil microflora in its degradation.

    Surprisingly, only a small amount of 14CO2 was released from
    nonsterilized soils treated with 14C-labelled diazinon (labelled at
    the 2-position on the pyrimidine ring). This result is not in
    agreement with the results on 14CO2 evolution from ring-labelled
    diazinon reported for nonflooded, soils (Getzin, 1967). This
    difference suggests that the fate of diazinon under submerged
    conditions might be different from that in nonflooded conditions.

    In the study of the persistence of diazinon (14C-labelled at the
    4-position on the pyrimidine ring) in submerged soils, soil microflora
    appeared to assist in its degradation into a less toxic hydrolysis
    product (2-isopropyl-6-methyl-4-hydroxypyrimidine). This hydrolysis
    product was, however, resistant to further degradation under submerged
    conditions (Sethunathan and Yoshida, 1969).

    From the foregoing, it appears that the major step in the degradation
    of diazinon in flooded soil is hydrolysis, resulting in the formation
    of 2-isopropyl-6-methyl-4-hydroxypyrimidine as one of the degradation
    products. Under submerged conditions, where the bulk of soil
    microflora is anaerobic, oxidation is negligible and the hydrolysis
    product tends to accumulate and persist in large quantities without
    being oxidized. The more rapid degradation of diazinon and the greater
    recovery of hydrolysis product from nonsterilized soils suggest that,
    in flooded soils, soil microflora play an important role - direct or
    indirect - in the hydrolysis of diazinon to
    2-isopropyl-6-methyl-4-hydroxypyrimidine, but not thereafter. The
    accumulation of 2-isopropyl-6-methyl-4-hydroxypyrimidine in submerged
    soils should not, however, pose a serious residue problem since, based
    on the anticholinesterase activity of the two compounds (Margot and
    Gysin, 1957), the hydrolysis product of diazinon is far less toxic
    than the parent molecule. In addition, drying the soil or increasing
    aeration during land preparation for the succeeding rice crop may
    completely eliminate this degradation product by oxidation.

    The decomposition of diazinon under nonflooded conditions, using two
    soil types in conjunction with three other factors, was explored by
    Bro-Rasmussen et al. (1968). These other factors considered were:

    (i)         activity of soil microorganisms
    (ii)        water content of soil
    (iii)       concentration of diazinon.

    The disappearance rate of diazinon varied considerably with half-lives
    ranging from 21 to 80 days. Results indicated that all factors
    influenced the rate of diazinon degradations and that microorganisms
    play an important role in the disappearance of diazinon from the soil.

    In storage and processing

    Residue levels of diazinon, diazoxon and
    2-isopropyl-4-methyl-pyrimidin-6-ol were measured in snap beans,
    spinach and tomatoes subjected to washing, blanching and pealing (for
    tomatoes) under simulated commercial conditions (Ralls et al., 1967).

    Diazinon on spinach at harvest 4 days after spraying was present at
    1.8 ppm and diazoxon at 0.34 ppm. A spray rinse did not significantly
    reduce residues. Detergent washing reduced diazinon to 0.77 ppm and
    diazoxon to 0.18 ppm, and steam blanching gave a total reduction to
    about 30 percent of the original residue. Only a water blanching
    process significantly reduced the level of the pyrimidinol metabolite
    from 2.5 ppm to 0.1 ppm. Residues at harvest (8 days) on snap beans
    and tomatoes were less than 0.1 ppm. Subsequent commercially simulated
    treatment appeared to have little or no effect, except possibly the
    commercial peeling of tomatoes. Further studies on the reduction of
    residues during food processing operations are reported by Farrow et
    al. (1969).

    Water washing of tomatoes (without detergent) removed 88 percent of
    total residues, but caused an apparent increase of 11 percent with
    spinach. A similar increase was seen with other insecticides such as
    parathion. Crops such as spinach and broccoli have large surface areas
    and are therefore subject to considerable leaching of water-soluble
    solids during washing. Since results are expressed on a dry weight
    basis, this results in an apparent increase in residue levels.

    Commercial blanching operations are carried out using either hot water
    or steam. Although washing was not effective in removing diazinon from
    spinach, hot water blanching removed 60 percent of the residue. During
    the combined canning operations it was found that there is a good
    overall removal of organophosphorus residues. Thus there was a 99
    percent removal of malathion residues from tomatoes, 94 percent
    removal from green beans and 66 percent removal of parathion from
    spinach; however, removal of parathion residues from broccoli, which
    is processed by snap freezing, amounted to only 10 percent.

    Diazinon is recommended in some countries for application to grapes,
    and Painter et al. (1963) studied the fate of diazinon after addition
    to grape must. Diazinon did not cause any measurable effect on
    fermentation and was not found in any component after fermentation.
    The absence of diazinon after fermentation is probably due to the
    hydrolysis of the compound under the acid conditions prevailing. It is
    interesting to note that several other organophosphorus compounds were
    detected in finished wine when subjected to similar experimental

    In water

    Gomaa et al. (1969) have considered breakdown of diazinon and diazoxon
    which may occur in water. Techniques were developed to study the
    hydrolysis of diazinon and diazoxon in aqueous media under varying
    conditions of temperature and pH. Diazinon and diazoxon are
    quantitatively hydrolysed to 2-isopropyl-4-methyl-6-hydroxypyrimidine
    and diethylthiophosphoric or diethylphosphoric acid.

    In general, at 20°C, diazoxon hydrolysis proceeds much faster than
    diazinon under comparable conditions. A large difference in rate of
    hydrolysis can be detected under acidic conditions, where diazoxon is
    hydrolysed 30 times faster than diazinon. The differences in rates
    decrease as neutrality is approached, but increase again as the pH of
    the hydrolysis solution increases.

    The work of Gomaa et al., indicates that some caution should be
    exercized concerning movement or application of diazinon into water.
    Sethunathan and MacRae (1969), suggested that soil microflora play an
    important part in the hydrolysis of diazinon in flooded soils. These
    conditions are unlikely to apply to aqueous media, which may account
    for the persistence of diazinon reported by Gomaa et al.

    Evidence of residues in food moving in commerce or at consumption

    Of some 14 800 randomly selected samples of raw agricultural products
    examined by the U.S. Food and Drug Administration from June 1965
    through 1966, only 32 samples showed any detectable residue of
    diazinon. Total diet studies conducted during 1965 and 1966 by the
    U.S. Food and Drug Administration revealed that 98 percent of the food
    samples contained no detectable residues of diazinon. The remaining 2
    percent contained only trace quantities. A multidetection gas
    chromatographic method, using an electron capture detector and/or a
    thermionic detector specific for phosphorus, was used for the
    analyses. The sensitivity of the method was about 0.05 ppm (Duggan et
    al., 1967).


    Most of the residue data summarized in this monograph were obtained
    using one or two of four different methods of analysis developed by
    Geigy Chemical Company (1956-67).

    A sulphide procedure was considered most accurate when spray history
    was known. In this procedure, diazinon is extracted from crops with a
    solvent and from the solvent with 48 percent HBr. The 48 percent HBr
    treatment adds a high degree of selectivity for the determination of
    diazinon. Upon boiling the acid solution, diazinon sulphur is
    converted to H2S and distilled off. It is collected in zinc acetate
    solution and then converted to a methylene blue complex, which is
    determined spectrophotometrically. Sensitivity of the sulphide
    procedure is about 0.1-0.2 ppm. Some crops, such as kale, had high
    natural sulphur blanks, so these crops were analysed by a phosphate
    method. Thiocarbamates such as ferbam also interfere and must be
    removed by an additional cleanup step.

    Some phosphorothioates are known to form relatively stable metabolic
    products containing no sulphur, for which the method described above
    would not be applicable, so a cholinesterase inhibition method was
    utilized to validate the sulphide procedure. The method based on
    determining the phosphorus of diazinon and one based on the
    ultraviolet absorption properties of the pyrimidine portion of the

    molecule are fraught with high blank and cleanup problems. Sensitivity
    of these methods is about 0.3-0.4 ppm.

    None of these four methods was of adequate sensitivity or specificity
    for "total diet" samples. Such data were not possible until the GLC
    methods based on electron capture and thermionic detectors were used.
    Diazinon and diazoxon are detected and may be determined by the
    multiresidue method of Abbott et al. (1970), which was successfully
    used in the total diet studies carried out in England and Wales. The
    methods of Storherr et al. (1964, 1965), using an ethyl acetate
    extraction and either a sweep codistillation or celite column cleanup
    with gas chromatographic detection, provide a rapid and adequately
    sensitive procedure for diazinon in most food commodities.

    J. R. Geigy SA has developed a gas chromatographic method which is
    applied following a shakeout with 48 percent HBr. The gas
    chromatographic methods are sensitive to about 0.01 ppm or better. A
    number of thin layer chromatographic procedures described in the
    literature will provide a confirmative test. Specific analytical
    methods for the detection of diazinon have been considerably refined
    in recent years. Extraction, cleanup and analytical techniques have
    been reviewed by Eberle (unpublished).

    An improved procedure for routine determination of diazinon residues
    in fruits, vegetables, soils, etc. using various selective gas
    chromatographic detector systems has been reported by Eberle and Novak
    (1969). Possible metabolites with strong cholinesterase-inhibiting
    activity are detected on TLC plates by fly-head cholinesterase
    inhibition with a limit of detection of 0.002 ppm. The above method is
    considered a marked improvement over previously described methods and
    permits determination of diazinon residues in a variety of crops
    together with detection of cholinesterase-inhibiting metabolites.


    Table VII summarizes national tolerances which have been established
    for diazinon.

        TABLE VII

    Country            Tolerance (ppm)      Crop

    Australia          0.75                 fruits, grains, vegetables

    Canada             0.1                  maize, peas
                       0.25                 melons, figs, cranberries and
                                            7 vegetables

    TABLE VII (cont'd)

    Country            Tolerance (ppm)      Crop

    Canada             0.5                  beans, cucumbers, turnips
    (continued)        0.75                 tree fruits including citrus,
                                            grapes, strawberries and 16

    Germany            0.5                  on or in vegetables, fruits,
    (Fed. Rep.)                             root crops, leg-wes, grapes
                                            and hops

    Hungary            0.5                  food

    India              0 (proposed)         cereals

    Italy              2                    olive oil

    Netherlands        0.5                  on or in
                                            (i)  vegetables or parts thereof
                                                 for consumption, including
                                                 edible mushrooms and edible
                                                 roots, bulbs and tubers

                                            (ii) edible fruits of vegetables
                                                 and fruit crops or parts

    New Zealand        0.75                 food

    Switzerland        The Swiss Intercantonal commission for
                       toxic materials ("Commission Intercantonale
                       des Toxiques") proposes a tolerance of 0.5
                       ppm. Federal regulations are in preparation

    U.S.A              0.1                  banana pulp, potatoes, sweet
                       0.2                  bananas
                       0.5                  almonds, filberts, pecans and
                       0.75                 ca 25 fruits and 25 vegetables,
                                            fat of meat and meat byproducts
                                            of cattle and sheep
                       1                    olives and olive oil
                       3                    almond hulls
                       10                   5 hays

    TABLE VII (cont'd)

    Country            Tolerance (ppm)      Crop

                       25                   bean and pea forage
                       40                   alfalfa (fresh), clover (fresh)
                                            and maize forage
                       60                   pasture grasses

    Diazinon was first synthesized in 1951 and introduced as an
    experimental insecticide in 1952. Initial development of the product
    was prompted by the appearance of DDT resistance in flies, mosquitoes
    and other insects. Extensive markets were developed for the product in
    the late 1950's, and major areas of use included control of pests in
    maize and alfalfa (U.S.A.), control of cockroaches and other insects
    in buildings, the control of sheep ectoparasites (Australasia) and
    control of a variety of insects attacking fruit and vegetables (Europe
    and U.S.A.).

    Diazinon does not persist for lengthy periods in either plant or
    animal tissues. Resistant action depends on a combination of factors
    including plant or animal species, application rates, cultural
    practices, climatic conditions, etc. In most instances, the half-life
    on crops is two to three days, except in olives where it ranges from
    12 to 25 days, depending on stage of maturity of the olive at

    In plants, diazoxon has been established as the principal
    anticholinesterase metabolite, though it occurs only as an
    insignificant fraction of the whole residue. This metabolite is in
    turn rapidly converted to noncholinesterase-inhibiting products.
    Studies with radio-labelled insecticide have shown that in plants,
    water and soil as well as mammals, detoxification of the insecticide
    takes place during the metabolism in all systems examined where
    residues are likely to occur.

    Several analytical methods are available for determining residues in
    plant or animal tissue. When utilized in accordance with good
    agricultural practice, the treated product may have residues up to the
    proposed tolerances, but only a small portion of each food commodity
    in these categories is likely to be treated. There are data showing
    that a significant amount of reduction in residues will take place
    during washing, preparation and processing of food for consumption. In
    "total diet" samples, diazinon has seldom been found, and then only at
    a low level. Residue data are available on more than 70 crops from
    several different countries.


    The following tolerances are based on residues likely to be found at
    harvest following currently approved use patterns. On commodities
    other than nuts, oilseeds, olives, olive oil and fat of meat, residues
    will continue to decline during storage and shipment with a probable
    half-life of less than five days.

    The tolerances are expressed as diazinon, since it is known that the
    oxygen analogue, diazoxon, if present, does not occur at
    concentrations above 0.004 ppm.

    Peaches, citrus and cherries                  0.7 ppm

    Other fruits                                  0.5 ppm

    Leafy vegetables                              0.7 ppm

    Other vegetables                              0.5 ppm

    Grain (wheat, barley, rice)                   0.1 ppm

    Nuts almonds, walnuts, filberts
    pecans, groundnuts)                           0.5 ppm

    Oilseeds (cotton, safflower, sunflower)       0.5 ppm

    Sweet maize (on kernels and cob with
    husks removed)                                0.7 ppm

    Olives and olive oil                          2 ppm

    Fat of meat of cattle, sheep and pigs



    1. Reproduction studies on one rodent and one nonrodent species.

    2. Toxicological information on residual anticholinesterase
       metabolites of diazinon in plants.


    Abbott, D. C., Crisp, S., Tarrant, K. R. and Tatton, J. O'G (1970)
    Pesticides in the total diet in England and Wales 1966-67. Pest. Sci.,
    1(1): 10-13

    Bartsch, E. (1970) Residue data of diazinon. J. R. Geigy SA,
    Switzerland (unpublished)

    Bourne, J. R. and Arthur, B. W. (1967) Diazinon residues in the milk
    of dairy cows. J. econ. Ent., 60: 402-405

    Boyd, E. M. and Carsky, E. (1969) Kwashiorkorigenic diet and diazinon
    toxicity. Acta. pharmacol. Toxicol., 27: 284-294

    Boyd, E. M., Carsky, E. and Krijnen, C. J. (1969) The effects of diets
    containing from 0 to 81 percent casein on the acute oral toxicity of
    diazinon. Clin. Toxicol., 2: 295-302

    Bro-Rasmussen, F., Noddegaard and Voldum-Clausen, K. (1968)
    Degradation of diazinon in soil. K.J. Sci. Fd. Agr., 19: 278-281

    Claborn, H. V., Mann, R. D., Younger, R. L. and Radeleff, R. D. (1963)
    Diazinon residues in the fat of sprayed cattle. J. econ. Ent., 56(6):

    Coffin, D. E. and McKinely, W. P. (1964) The metabolism and
    persistence of systox, diazinon and phosdrin on field-sprayed lettuce.
    J. Assoc. Off. Agr. Chem., 47(4): 632-640

    Derbyshire, J. C. and Murphy, R. T. (1962) Diazinon residues in
    treated silage and milk of cows fed with powdered diazinon. J. Agr.
    Fd. Chem., 10(5): 384-386

    Duggan, R. E., Barry, H. C. and Johnson, L. Y. (1967) Pesticide
    residues in total diet samples. II. Pest. Monitor. J., 1(2): 2-12

    Earl, F. L., Melveger, B. E., Reinwall, J. E., Bierbower, G. W. and
    Curtis, J. M. (1970) Diazinon toxicity - comparative studies in dogs
    and miniature swine. Toxicol. appl. Pharmacol. (in press)

    Eberle, D. O. (1970) Analysis of diazinon. J. R. Geigy SA, Switzerland

    Eberle, D. O. and Novak, D. (1969a) Fate of diazinon in field sprayed
    agricultural crops, soil and olive oil. J. Assoc. Off. Anal. Chem.,
    52: 228

    Eberle, D. O. and Novak, D. (1969b) Fate of diazinon in field sprayed
    agricultural crops, soil and olive oil. J. Assoc. Off. Anal. Chem.,
    52: 1067-1074

    Edson, E. F. and Noakes, D. N. (1960) The comparative toxicity of six
    organophosphorus insecticides in the rat. Toxicol. appl. Pharmacol.,
    2: 523-539

    FAO/WHO. (1965) Evaluation of the toxicity of pesticide residues in

    FAO/WHO. (1968) 1968 evaluations of some pesticide residues in food.
    FAO/PL:1968/M/9/1. WHO/Food Add./69-35

    Farrow, R. P., Elkins, F. R., Rose, W. W., Lamb, F. C., Ralls, J. W.
    and Mercer, J. W. (1969) Canning operations that reduce insecticide
    levels in prepared foods and in solid food waste. Residue Reviews,
    29: 73-87

    Gaines, T. B. (1969) Acute toxicity of pesticides. Toxicol. appl.
    Pharmacol., 14: 515-534

    Geigy Chemical Company. (1956-67) Unpublished data and methods of
    analysis in pesticide petitions, submitted to the U.S. Food and Drug

    Geigy Chemical Company. (1969) Diazinon-deterioration-stabilization
    and influence on toxicity. Unpublished report

    Getzin, L. W. (1967) Metabolism of diazinon and zinophos in soils. J.
    econ. Ent., 60: 505-508

    Getzin, L. W. and Rosefield, I. (1966) Persistence of diazinon and
    zinophos in soils. J. econ. Ent., 59(3): 512-516

    Gomaa, H. M., Suffett, I. H. and Faust, S. D. (1969) Kinetics of
    hydrolysis of diazinon and diazoxon. Residue Reviews, 29: 171-190

    Gunner, H. B., Zukerman, B. M., Walker, R. W. Miller, C. W., Denbert,
    K. H. and Longley, R. E. (1966) The distribution and persistence of
    diazinon applied to plant and soil and its influence on soil
    microflora. Plant Soil; 25: 249-264

    Gunther, F. A., Ewart, W. H., Blinn, R. C., Elmer, H. S. and Wacker,
    G. B. (1958) Field persistence comparisons of residues of the
    insecticide diazinon in lemons and Valencia oranges and effects on
    juice flavour. Agr. Fd. Chem., 6: 521

    Harrison, D. L. and Hastie, B. A. (1965) Diazinon residues in the milk
    of cows and fat of sheep after feeding on pasture treated with
    diazinon. New Zealand J. agr. Res., 9: 1-7

    Hastie, B. A. (1963) The metabolism and elimination of diazinon from
    animals, animal tissues and foodstuffs. Geigy Agricultural Chemicals,
    Australia (bulletin)

    Hastie, B. A. (1965) Diazinon residues in sheep fat. Geigy
    Agricultural Chemicals, Australia (unpublished)

    Kaplanis, J. N., Louloudes, S. J. and Roan, C. C. (1962) Trans. Kansas
    Acad. Sci., 65: 70-75

    Maier-Bode, H. (1963) Residues of insecticides on cover crops growing
    in orchards after application of organic phosphorus toxicants on the
    trees. Z. Pflanzenkrankh. Pflanzenschutz, 70(80): 449-459

    Maier-Bode, H. (1967) Untersuchungen über den Gehalt
    landwirtschaftlicher und gärtnerischer Ernteprodukte an
    Pflanzenschutzmittelrückständen. Der Ministerpräsident des Landes
    Nordrhein-West., Landesamt für Forschung, Jahrbuch 1967, S. 391.

    Margot, A. and Gysin, H. (1957) Diazinon, its degradation products and
    their properties. Belv. Chim. Acta., 40: 1562

    Mathysse, J. G. and Lisk, D. (1968) Residues of diazinon, coumaphos,
    ciodrin, methoxychlor and rotenone in cow's milk from treatments
    similar to those used for ectoparasite and fly control on dairy
    cattle, with notes on safety of diazinon and ciodrin to calves. J.
    econ. Ent., 61(5): 1394-1398

    Melchiorri, P. Maffei F. and Siesto. A. J. (1964) Farmaco (Pavia), Ed.
    Prat., 19: 610

    Michel, H. O. (1949) J. lab. clin. Med., 34: 1564

    Millar, K. R. (1963) Detection and distribution of 32P-labelled
    diazinon in dog tissues after oral administration. New Zealand vet.
    J., 11(6): 141-144

    Mücke, W., Alt, K. O. and Esser, H. O. (1970) Degradation of
    14C-labelled diazinon in the rat. J. Agr. Fd. Chem., 18(2): 208-212

    Nakatsugawa, T., Tolman, N. M. and Dalm, P. A. (1969) Oxidative
    degradation of diazinon by rat liver microsomes. Brochem. Pharmacol.,
    18: 685-688

    Nelson, L. L. and Hamilton, E. W. (1970) Metabolism of diazinon in
    alfalfa. J. econ. Ent., 63(3): 874-878

    Onsager, J. A. and Rusk, H. W. (1967) Adsorption and translocation of
    diazinon and Stauffer N-2790 in sugarbeet seedlings. J. econ. Ent.,
    60(2): 586-588

    Painter, R. P. and Kilgore, W. W. (1963) Distribution of pesticides in
    fermentation products obtained from artificially fortified grape
    musts. J. Fd Sci., 28: 342-346

    Pardue, J. R., Hansen, E. R., Barron, R. P. and Chen, J. J. (1970)
    Diazinon residues on field-sprayed kale. Hydroxydiazinon - a new
    alteration product of diazinon. J. Agr. Fd Chem., 18: 405-408

    Rai, L. and Roan, C. C. (1959) Report included in Geigy Chemical
    Company pesticide petition to the U.S. Food and Drug Administration

    Ralls, J. W., Gilmore, D. R. and Cortes, A. (1966) Fate of radioactive
    o,o-diethyl o-(2-isopropyl-4-methylpyrimidin-6-ol) phosphorothioate on
    field grown experimental crops. J. Agr. Fd Chem., 14(4): 387-392

    Ralls, J. W., Gilmore, D. R., Cortes. A., Schutt, S. H. and Mercer, W.
    A. (1967) Residue levels of diazinon and its transformation products
    on tomatoes, spinach and beans. Fd Tech., 21: 92-94

    Robbins, W. E., Hopkins, T. L. and Eddy, O. W. (1957) Metabolism and
    excretion of phosphorus-32-labelled diazinon in a cow. J. Agr. Food
    Chem., 5(7): 509-513

    Robens, J. F. (1969) Teratologic studies of carbaryl, diazinon, norea
    disulfiram and thiram in small laboratory animals. Toxicol. appl.
    Pharmacol., 15: 152-163

    Sethunathan, N. and MacRae, I. C. (1969) Persistence and
    biodegradation of diazinon in submerged soil. J. Agr. Fd Chem., 17:

    Sethunathan, N. and Yoshida, T. (1969) Fate of diazinon in submerged
    soil. Accumulation of hydrolysis product. J. Agr. Fd Chem., 17(6):

    Siesto, A. J., Maffei, F. and Melchiorri P. (1964) Estratto da
    Archivio Italiano di Scienze Farmacologiche, Series 3, 13: 3

    Storherr, R. W., Getz, M. E., Watts, R. R., Friedman, S. J., Erwin,
    F., Giuffrida, L. and Ives, F. (1964) Identification and analyses of
    five organo-phosphate pesticides. Recoveries from crops fortified at
    different levels. J. Assoc. Off. Agr. Chem., 47(6): 1087-1093

    Storherr, R. W. and Watts, R. R. (1965) A sweep co-distillation
    cleanup method for organophosphate pesticides. J. Assoc. Off. Agr.
    Chem., 48(6): 1154-1160

    Vigne, J. P., Chouteau, J., Tabau, R.-L., Rancien, P. and Karamanian,
    A. (1957) Sur le métabolisme d'un insecticide organo-phosphoré, le
    diéthylthionophosphate de 2 isopropyl 4 méthyl 6 oxypyrimidine chez la
    chèvre. Bull. Acad. Vét. Fr., 30: 85-92

    See Also:
       Toxicological Abbreviations
       Diazinon (EHC 198, 1998)
       Diazinon (ICSC)
       Diazinon (FAO Meeting Report PL/1965/10/1)
       Diazinon (FAO/PL:CP/15)
       Diazinon (FAO/PL:1967/M/11/1)
       Diazinon (FAO/PL:1968/M/9/1)
       Diazinon (WHO Pesticide Residues Series 5)
       Diazinon (Pesticide residues in food: 1979 evaluations)
       Diazinon (Pesticide residues in food: 1993 evaluations Part II Toxicology)
       Diazinon (JMPR Evaluations 2001 Part II Toxicological)