Chemical name

         O,O-diethyl phosphorodithioate.


         phosphorodithionate; triazotion (common name in USSR);
         Ethyl-Gusathion(R) Ethyl-Guthion(R). (R)Gusathion A,
         (R)Gusathion K-forte; (R)Gusathion H.
         Bay 16259
         R 1513

    Structural formula


    empirical formula: C12H16N3O3PS2

    Other information on identity and properties

    (a) Composition of technical azinphos-ethyl

         The technical material contains a minimum of 92% azinphos-ethyl.


    triethyl thiophosphate and
    triethyldithiophosphate                      together max. 2.0%

    bis(3,4-dihydro-4-oxo-1,2,3-triazin-3-ylmethyl)-sulfide  together
    and -disulfide                                           max. 1.5%

    benzotriazin and (3,4-dihydro-4-oxo-1,2,3
    benzotriazin-3 ylmethyl)-methylsulfide       together max. 1.5%

    ethylene-bis (O,O-diethyl-dithiophosphate)   max. 1.9%

    benzotriazin-3-yl(-methyl)-dithiophosphate   max. 0.7%

    bis (3,3-dihydro-4-oxo-benzotriazin-3-yl-methyl)-ether  max. 0.6%

    0-ethyl-S-(3,4, dihydro-4-oxo-1,2,3
    benzotriazin 3-yl-methyl)-dithio-phosphoric
    acid                                         max. 0.5%

    water                                        max. 0.2%

    (b)  Physical and chemical properties of azinphos-ethyl

    Physical state:          colourless crystals.

    Molecular weight:        345.4.

    Melting point:           53°C (pure material).

    Boiling point:           147°C at 0.01 mm Hg
                             111°C at 0.001 mm Hg

    Volatility:              0.0012 mg/cu metre at 10°C
                             0.0042 mg/cu metre at 20°C
                             0.0128 mg/cu metre at 30°C
                             0.0372 mg/cu metre at 40°C

    Vapour pressure:         6.3 x 10-8 mm Hg at 10°C
                             2.2 x 10-7 mm Hg at 20°C
                             7 x 10-7 mm Hg at 30°C
                             2.1 x 10-6 mm Hg at 40°C

    Specific gravity:        D 20 = 1.284
    Refractive index:        N 53 = 1.592
    Solubility:              practically insoluble in water,
                             soluble in most organic solvents

    Formulations used:       emulsifiable liquid 25% w/v, 40% w/v
                             wettable powder 25%, 33%, 40%
                             ULV formulation 500 g/l


    Biochemical aspects

    Absorption, distribution and excretion

         Following oral and I.V. administration of 14C-labelled
    azinphos-ethyl to male rats in doses of 0.1 or 2 mg/kg bw, about 60%
    of the activity was excreted in urine and 30% in faeces in 48 hours.
    Approximately 30% of a 2 mg/kg dose was eliminated in bile within 24
    hours; less than 0.1% was eliminated in expired air, indicating that
    the benzotriazine ring does not undergo extensive degradation.
    Approximately 6% of activity was present in the body 48 hours after
    administration, the mean concentration in tissues being equivalent to
    0.1 ppm. The highest equivalent concentration (0.2-0.3 ppm
    (0.00002%-0.00003%)) was found in blood and 0.15-0.2 ppm
    (0.000015%-0.00002%) was found in lungs, liver and kidneys. The
    results of an exactly similar study using azinphos-methyl showed no
    differences, indicating that mammals metabolize both compounds in a
    similar manner (Anon., 1973).

    Effects on enzymes and other biochemical parameters

         Brain cholinesterase activity in vitro was reduced by 50% by
    1.4 x 10-5 molar azinphos-ethyl; this was considered to be due to the
    presence of impurities with anticholinesterase activity. A single I.P.
    dose of 3.4 mg azinphos-ethyl/kg reduced serum, brain and submaxillary
    gland cholinesterase activity to approximately the same extent.
    Maximum inhibition occurred within an hour and activity returned to
    normal gradually, reversal not being complete by 70 hours. On
    incubation with liver preparation, azinphos-ethyl was transformed into
    a potent anticholinesterase compound, probably the oxygen analogue
    (Dubois et al., 1959).


    Special studies on neurotoxicity

         Groups of three hens received a single dose of 10 or 25 mg
    azinphos-ethyl/kg and were observed for five weeks. One bird on the 25
    mg/kg level died after 26 days but no signs of demyelinating disease
    developed (Kimmerle, 1960).

         Groups of four hens were fed on diet containing 0, 75, 150, 300
    and 600 ppm (0, 0.0075, 0.015, 0.03 and 0.06%) azinphos-ethyl for 30
    days.  Loss of body weight occurred at the two highest dosage levels
    and a significant depression of whole blood cholinesterase activity at
    the 600 ppm (0.06%) level. No signs of neurological damage occurred
    during the dosage period or during the subsequent four-week
    observation period. Histological examination of femoral fixed brain,
    spinal cord and femoral nerve failed to detect evidence of
    demyelination or nerve damage (Kimmerle, 1968; Grasso, 1969).

    Special studies on potentiation and antidotes

         No significant potentiation of acute toxicity occurred with
    azinphos-ethyl in combination with parathion, methyl parathion,
    systox, EPN, malathion, trithion, phosdrin, sevin, delnav, OMPA,
    diazinon, azinphos, di-syston, Co-Ral, Folex or Ronnel. A twofold
    potentiation occurred with azinphos-ethyl and ethion (Dubois and
    Raymond, 1960a; Dubois, 1963; Kimmerle, 1966a).

         The effects of azinphos-ethyl are counteracted by atropine and by
    reactivating compounds. The two drugs given in combination give more
    pronounced effects (Kimmerle, 1966; Lorke and Kimmerle, 1968;  Dubois
    et al., 1959).

    Acute toxicity

    Species        Route     Sex     mg/kg bw      References

    Mouse          I.P.              3.8-4.0       Dubois et al., 1959

    Rat            Oral              12.0-20.5     Ben-Dyke et al., 1970
                                                   Kimmerle, 1959,
                                                   1966 a & b

                             F       7.0           Dubois et al., 1959
                             M       15.2

    Rat            I.P.      F       4.4           Dubois et al., 1959
                             M       9.2
                             M       7.5           Kimmerle, 1959

    Rat            Dermal            75-280        Ben-Dyke et al., 1970
                                                   Dubois et al., 1959
                                                   Kimmerle, 1959

    Guinea-pig     Oral              17            Dubois et al., 1959
    Guinea-pig     I.P.              8.0           Dubois et al., 1959
    Chicks         Oral              34            Sherman et al., 1967

    F = Female;   M = Male.

    Short-term studies

    Rat.  Twenty-four male rats received an oral dose of 1 mg
    azinphos-ethyl/kg bw on each of 28 consecutive working days. The rate
    of weight gain was normal and signs of poisoning did not occur.
    Erythrocyte cholinesterase showed 50% depression after 2, 82% after 3
    and 90% after 28 days' treatment. Activity had returned to normal 35
    days after treatment stopped (Kimmerle, 1959).

         Groups of five female rats received daily I.P. injections of
    azinphos-ethyl at dosage levels of 0.5, 1, 2 and 3 mg/kg bw for 60
    days. Only the two highest dosage levels caused a reduction in the
    rate of weight gain and an increased mortality (Dubois and Raymond,

         Groups of 15 male and 15 female rats received diet containing 0,
    1, 2, 4 and 8 ppm (0, 0.0001, 0.0002, 0.0004 and 0.0008%) for three
    months. No effects were found on growth rate, food consumption,
    mortality rate or on the results of haematological investigations and
    analysis of blood. The 4 ppm (0.0004%) level had no significant effect
    on plasma enzyme but depressed the erythrocyte cholinesterase activity
    after one month. The 8 ppm (0.0008%) level depressed plasma enzyme
    after only one week's exposure and prolonged exposure caused no
    further depression; erythrocyte enzyme activity continued to fall
    during the first month's exposure. In general, females appeared to be
    more sensitive than males. Autopsy, determination of organ weights and
    histological examination of organs and tissues detected no abnormality
    in animals fed azinphos-ethyl (Löser, 1969; Mawdesley-Thomas and
    Urwin, 1969).

         Groups of 12 male and 12 female rats were fed on diets containing
    0, 5, 10 and 50 ppm (0, 0.0005, 0.001 and 0.005%) azinphos-ethyl for
    16 weeks. The growth rate of female animals was unaffected while male
    rats receiving 50 ppm (0.005%) showed a slightly reduced rate of
    growth compared with controls. No animals showed signs of
    cholinesterase inhibition but determination of the activity of the
    enzyme in serum, erythrocytes, submaxillary and brain tissue of five
    male and five female rats of each group showed that it was markedly
    inhibited in the 50 ppm (0.005%) group. Inhibition was most marked in
    erythrocytes (87%) and serum (85%) and less marked In brain (24% in
    males and 72% in females) and gland tissue (16% in males and 59% in
    females). Serum and erythrocyte activity was depressed (52% and 80%
    respectively) in rats fed 10 ppm (0.001%) azinphos-ethyl in their
    diet. Only erythrocyte enzyme was significantly inhibited in rats on 5
    ppm (0.0005%) diet; males and females did not differ in this respect.
    The remaining seven animals of each sex of each group were autopsied
    and the organs weighed and examined histologically but the results of
    this examination are not reported (Doull and Root, 1960).

    Dog. Groups of two male and two female dogs aged between 6 and 14
    months were fed for 12 weeks on diets containing 0.25, 0.5, 1, 2, 3
    and 10 ppm, (0.000025, 0.0005, 0.0001, 0.0002, 0.0003 and 0.001%)
    azinphos-ethyl. The serum and erythrocyte cholinesterase activity was
    determined periodically before, during and following the dosage
    period. Dogs receiving 3 and 10 ppm (0.0003 and 0.001%) diets
    exhibited signs of cholinesterase activity depression and were taken
    off the diets after 1 and 6 weeks respectively. Over 50% inhibition
    occurred in the serum and erythrocytes of dogs fed on 2 ppm (0.0002%)
    diet. Erythrocyte enzyme activity was not inhibited in dogs receiving
    the 0.25% diet but the serum enzyme was inhibited by about 20%. Since
    the serum cholinesterase activity in control animals was inhibited by
    10% the no-effect level was considered to be approximately 0.25 ppm

    (0.000025%). In the animals affected, activity was reduced during the
    first week of the test and then remained constant while the
    erythrocyte enzyme tended to decrease gradually throughout the 12-week
    test period. Cholinesterase activity returned to normal in 3-4 weeks
    when dogs on the highest dosage levels were transferred to control
    diet and in 2-3 weeks with the 0.5 and 1 ppm (0.00005 and 0.0001%)
    groups (Doull et al., 1963).

    Long-term studies

    No data available.


         Azinphos-ethyl is absorbed from the gastrointestinal tract and
    excreted in urine and bile. It does not accumulate in tissues. The
    absorption, distribution and excretion of radiolabel by rats are
    similar in animals administered 14C-labelled azinphos-ethyl or
    -methyl. However, insufficient data are available to determine the
    metabolic pathway of azinphos-ethyl and to compare it with that of
    azinphos-methyl, although there is evidence that in both the
    benzotriazine moiety remains intact.

         Azinphos-ethyl inhibits acetylcholinesterase activity in plasma,
    erythrocyte, brain and submaxillary gland and a series of low doses
    causes the plasma activity of rats and dogs to fall rapidly to a
    stable level while erythrocyte acetylcholinesterase tends to fall more
    gradually over a longer period. Female rats were more sensitive than
    males as shown by the degree of enzyme inhibition and, in some tests,
    by LD50 values. Recovery of enzyme activity took several weeks
    following cessation of exposure of rats.

         Short-term studies in rats show the no-effect level to be 2 ppm
    (0.0002%) in the diet. The only toxic effects seen were attributed to
    depression of cholinesterase activity. In an investigation using dogs,
    in which only plasma and erythrocyte cholinesterase activity were
    recorded, the no-effect level was 0.25 ppm (0.000025%) in the diet.

         The Meeting was unable to estimate an acceptable daily intake for
    this substance in the absence of sufficient information on the
    identity and toxicity of its metabolites, on its possible effects on
    reproduction, on its long-term toxicity and on its carcinogenic and
    teratogenic and mutagenic potential.


    Use pattern

         Azinphos-ethyl is a non-systemic organophosphorus insecticide,
    which is used against a relatively broad spectrum of insects e.g.
    Lepidopterous larvae, beetles and their larvae, aphids, jassids and
    spider mites on various crops: cotton, rice, sugar and fodder beets;
    fruits such as apples, pears, citrus-fruit, grapes; tobacco.

         Azinphos-ethyl is used in about 35 countries in Europe, Africa,
    Asia, Australia, New Zealand, North, Central and South America.

         The amounts used on different crops vary greatly from year to
    year depending on the pest situation. A rough estimate may be given:

         cotton and other agricultural crops     60%
         fruit crops (including grapes)          30%
         vegetables (including potatoes)         10%

    Pre-harvest applications

         Azinphos-ethyl is generally used at dosages of 0.04-0.05% active
    ingredient. The officially registered and/or recommended uses of
    azinphos-ethyl are summarized below, with the application rates and
    pre-harvest intervals.


    Crop                          Dosage rate         Minimum pre-harvest
                                  g a.i./ha           interval - days

    Agricultural crops
      cotton                      250-1 000           5

      rice                        300-500             14

      tobacco                     300-600             14

      sugar- and fodder beets     300-500             14

    Fruit crops
      apples, pears, peaches,

      plums and cherries          800-1 000           14-21

      citrus fruit                800-1 000           14-21

      grapes                      800-1 000           14-21

      brassicas                   300-500             7-14

      melons                      300-500             7-14

      tomatoes                    300-500             7-14

      potatoes                    300-                14-

    Hops                          400-800             14

    Pre-harvest intervals officially recommended in different
    countries, days

    Australia           general                       21 days

    Bulgaria            sugar beets                   14 days

    Fed. Rep. of        field crops as:
    Germany             cereals, rape, alfalfa,
                        sugar and fodder beets
                        potatoes                      14 days

                        beans                         21 days

                        cucumbers, tomatoes           14 days

    United Kingdom      apples, pears                 21 days
                        cucumbers and tomatoes
                        (glasshouse cultures)         2 days

    France              general                       15 days

    Italy               general                       20 days

    Morocco             olives                        30 days
                        other crops                   15 days

    New Zealand         root vegetables               14 days
                        smooth-skinned fruit          14 days
                        other fruit and
                        vegetables                    21 days

    Netherlands         potatoes                      28 days

    Portugal            tomatoes for industrial
                        processing                    5 days
                        all other crops               21 days

    Switzerland         fruit, grapes                 21 days
                        potatoes                      21 days

    Spain               cotton                        21 days (2%
                                                      dust 15 days)

                        sugar beets                   21 days
                        hazelnuts                     21 days

    South Africa        potatoes                      21 days

    Pre-harvest intervals officially recommended in different
    countries, days

    South Africa        cotton                 5 days (not
    (Cont'd.)                                  to be used for
                                               feeding purposes
                                               until after 35 days)

    Yugoslavia          fruit                  21 days

    Residue data from supervised trials

         Residue data are available from trials on various fruit,
    vegetables and field crops: apple; kidney bean, soybean, cauliflower,
    kohlrabi, savoy, potatoes; tobacco; the data obtained are summarized
    in the following table.

    Residues in food moving in commerce

         In the Federal Republic of Germany in 1965 and 1968 a total of
    228 samples of fruit and vegetables, home produced and imported,
    analysed for organophosphorous compounds.

         Only in one of these 220 samples azinphos-ethyl was detected, the
    residue level being less than 0.1 ppm (Krause, 1969).

         Azinphos-ethyl was not found in any of the 378 sub-samples of a
    total diet study carried out in England and Wales in 1966-67 (Abbott
    et al., 1970).

    Fate of residues

    In mammals

         14C-labelled azinphos-ethyl and azinphos-methyl was administered
    orally and intravenously to about 50 male rats (Sprague - Dawley
    approx. 170 g). The compounds were applied in a solvent mixture
    containing 5% Cremophor EL.

         The radioactivity measured related to the sum of the unchanged
    parent compound and its metabolites.

         After oral as well as after intravenous administration about 65%
    (57-68%) of the applied activity was eliminated in the urine within 48
    hours, and about 30% (26-34%) in the faeces (see table).



                                           Application                           Pre-harvest interval in days
    Crop           Country      Year         rate kg                                                                                       >35
                                       No.   a.i./ha   formulation   0         2/3       6/8       10/13     14/15     21/23     28/31     (...days)

    Field crops

    cottonseed     USA          1968   14    0.56      E.C. 12                           <0.01               <0.01
                                       10    "                                           <0.01               <0.01
                                       13    "                                           0.01                0.01
                                       10    "                                           <0.01               0.01

    gin trash      USA          1968   14    0.56      E.C.12                            2.71                1.96
                                       10    "                                           1.28                0.75
                                       13    "                                           0.22                0.12
                                       10    "                                           5.07                3.07

    foliage        USA          1968   14    0.56      E.C.12                            16.45               8.81
                                       10    "                                           1.20                0.60
                                       13    "                                           0.35                <0.07
                                       10    "                                           11.41               11.47

    rape seed      Germany      1971   1     0.3       w.p. 33%                                                                            n.d.(74)

    Fruit crops

    Cox's and      UK           1961   3     1.13      w.p. 25%      0.3                 <0.3                <0.3      <0.3             n.d.(47)
    Cox's          UK           1961   2     1.4       w.p. 25%      1.04                          0.66                0.43      0.42
    Delicious      Belgium      1969   1     1.25      E.C. 50%                                    0.94                0.44      0.19      0.09 (42)

    TABLE 1. (Cont'd.)


                                           Application                           Pre-harvest interval in days
    Crop           Country      Year         rate kg                                                                                       >35
                                       No.   a.i./ha   formulation   0         2/3       6/8       10/13     14/15     21/23     28/31     (...days)


    French         Germany      1972   1     0.3       E.C.250g/l    0.6                 0.05                n.d.      n.d.
    beans          Fed.Rep.     1972   1     0.3                     0.6                 0.06                n.d.      n.d.
                                1972   1     0.3                     0.12                0.07                n.d.      n.d.

    soybean        USA          1968   3     0.42      E.C. 12                                               0.55
    green plant                 1969   3     0.42      "                                                     0.79
    whole                       1968   3     0.42      "                       3.08                0.87
                                                                               (0.04)              (0.03)
                                1969   3     0.42      "             14.91     4.62      0.75                0.24
                                                                     (<0.02)   (<0.02)   (<0.02)             (<0.02)
                                1968   3     0.42      "             18.0      3.6       1.6                 0.9
                                                                     (<0.03)   (<0.16)   (<0.03)             (0.39)
    soybean        USA          1968   3     0.42      E.C. 12                                                                             0.26
    vines (dry)                                                                                                                            (<0.03)
                                                                                                                                           (45 d)
                                1969   3     "         "                                                               0.25
                                1968   3     "         "                                                                                   0.14
                                                                                                                                           (55 d)
                                1969   3     "         "                                                                                   0.01
                                                                                                                                           (48 d)
                                1968   3     "         "                                                                         0.23

    TABLE 1. (Cont'd.)


                                           Application                           Pre-harvest interval in days
    Crop           Country      Year         rate kg                                                                                       >35
                                       No.   a.i./ha   formulation   0         2/3       6/8       10/13     14/15     21/23     28/31     (...days)

    beans(dry)                  1968   3     0.42      E.C. 12                                                                             0.10
                                                                                                                                           (45 d)

                                1969   3     "         "                                                               0.01
                                1968   3     "         "                                                                                   0.01
                                                                                                                                           (55 d)

                                1969   3     "         "                                                                                   0.09
                                                                                                                                           (48 d)
                                1968   3     "         "                                                                         0.01

    cauliflower    Germany      1967   1     0.5       w.p.33%       2.95                0.15
                   Fed. Rep.

    kohlrabi       Germany      1968   1     0.5       w.p. 33%      0.25      0.07      0.04                n.d.
    (without       Fed.Rep.     1967   1     0.5       "             0.3                 0.06      0.01
    leaves)                     1967   1     0.5       "             0.4                 0.03      <0.01
                                1967   1     0.3       "             0.15                                    0.12      0.08

    savoy          Germany             1     0.3       w.p. 33%                0.32      0.27                0.15      0.12                0.14
                   Fed.Rep.                                                                                                                (36 d)

    cabbage        Germany      1967   1     0.3       w.p. 33%      0.18                0.07                0.06      <0.02
                   Fed. Rep.

    TABLE 1. (Cont'd.)


                                           Application                           Pre-harvest interval in days
    Crop           Country      Year         rate kg                                                                                       >35
                                       No.   a.i./ha   formulation   0         2/3       6/8       10/13     14/15     21/23     28/31     (...days)

    potatoes       USA          1962   8     0.42      E.C. 12                           n.d.
                                1962   8     "         "                                 n.d.
                                1962   8     " 1       "                                 n.d.
                                1962   8     "         "                                 n.d.
                                1962   8     "         "                                 n.d.
                   Netherlands  1972   1     0.20      w.p.25%                                                                   n.d.
                                1972   1     "         "                                                                         n.d.

    tomatoes       New
                   Zealand      1968   2     1.25      E.C. 44       1.03a     0.9a      0.78a               0.5la
                                1968   2     "                       1.5a      0.98a     1.28a               0.80a
                                1968   2     11.25     w.p. 25       1.10a     1.15a     0.66a               0.62a
                                1968   2     "                       1.97a     1.62a     0.94a               0.33a

    cured          USA          1967   3     0.84b     E.C. 12       227       119       63                  22
                                1968   3     0.84b     "             373       282       150                 75
                                1967   3     0.56      E.C. 12       117       138       27                  29
                                1967   3     "         "             79.5      58.6      40.5                7.2
                                1967   3     "         "             170       67        29                  19
                                1967   3     "         "             87        103       14                  8.7
                                1967   3     "         "             254       119       61                  22
                                1967   3     "         "             207       140       68                  40


    n.d. = not detectable.

    a Only residues on the peel; residue in the pulp 0.03-0.09 ppm.

    b Overdosage


                        Route of           Dosage     Number of      % of activity applied
    Compound            administration     mg/kg      animals        excreted in 48 hours

                                                                     urine          faeces

    azinphos-ethyl      i.v.               2          5              66 ± 2         26 ± 4

                        i.v.               0.1        5              59 ± 2         31 ± 4

                        p.o.               2          4              62 ± 2         30 ± 5

                        p.o.               0.1        5              57 ± 5         34 ± 6

    azinphos-methyl     i.v.               2          4              68 ± 3         26 ± 4

                        i.v.               0.1        5              63 ± 3         29 ± 4

                        p.o.               2          5              68 ± 4         26 ± 2

    About 50% of the dosage administered was excreted in 8-9 hours.


    Elimination in the bile

         Following intravenous administration of 2 mg/kg azinphos-ethyl or
    azinphos to each of three animals an average of approximately 30% of
    the applied activity was eliminated in the bile within 24 hours.

    Elimination of azinphos in the air

         Following oral or intravenous administration of 14C-labelled
    azinphos-ethyl less than 0.1% of the applied activity was eliminated
    in the expired air within 24 hours. This indicates that the
    benzotriazine ring in azinphos-ethyl does not undergo extensive
    metabolic degradation.

         Forty-eight hours after oral and intravenous administration of 2
    mg/kg azinphos-ethyl or azinphos to each of four or five animals 6% of
    the applied activity was still present in the animal; approximately 1%
    was present in the gastrointestinal tract.

         The mean concentration of azinphos-ethyl in the animal tissue
    (except the gastrointestinal tract) was at that moment about 0.1 µg/g
    tissue irrespective of the compound applied and the route of

    administration. Autoradiography and quantitative determination in
    single tissues showed that the activity was fairly evenly distributed.
    The highest concentrations were in the blood (0.2-0.3 µg/g).

         The equivalent concentrations in lung, liver and kidneys were
    0.15-0.2 µg/g.

         The concentrations measured in other organs were below the values
    mentioned above.

    Fate of residues in plants

         The metabolism of azinphos-ethyl was studied in cotton and bean
    plants under field conditions (Olson, 1969).

         The residue following application of azinphos-ethyl consisted
    partly of the P = 0 metabolite presumably owing to its higher chemical
    stability. After 14 days approximately 10% of the residue could be
    determined by TLC and GLC as the P = 0 analogue.

    Methods of residue analysis

         Several colorimetric, thin layer and gas chromatographic methods
    for residue analysis of azinphos-ethyl and relevant metabolites are
    described in the literature. Only those methods will be referred to
    which may be suitable for regulatory purposes or which can be adapted
    for these purposes.

    Colorimetric methods

         Miles (1964) developed a rapid colorimetric method for residue
    analysis of azinphos-ethyl, azinphos and their P = 0 metabolites in
    plant material.

         The method is based on the hydrolysis of the pesticide or
    metabolite molecule after separation in a medium of acetic and
    hydrochloric acid and the simultaneous coupling of the presumably
    formed intermediate benzazimide with N-(1-naphtyl)-ethylene diamine to
    produce a violet solution with an absorption maximum at 556 nm.

         The plant material is extracted with chloroform and the extract
    is carried through a clean-up procedure using Attaclay-celite. The
    oxygen analogues are separated in a Florisil column.  Azinphos-ethyl
    and azinphos-methyl are eluated with chloroform, the P = 0 analogues
    with an acetonechloroform mixture.

         The recoveries in plant material range from 78 to 97%.

         The lower limit of detection is about 5 µg of azinphosethyl and
    the P = 0 analogue.

         The method, which is specific for the benzotriazinyl group, was
    proved to be suitable for residue analysis on apples, tomatoes,
    cabbage and tobacco. No interference occurs with milligram quantities
    of carbaryl or the following organophosphorous pesticides: demeton,
    diazinon, dimethoate, disulfoton, EPN, malathion, parathion, phorate,
    schradan and trichlorphon.

         A similar colorimetric method for residue analysis of
    azinphos-ethyl in apples, potatoes, alfalfa and watermelons was
    described by Möllhoff (1969).

         The plant samples are treated with acetone; the parent compound
    is extracted with chloroform and then chromatographed in isopropanolic
    solution for clean-up. The alkaline hydrolysis leads to anthranilic
    acid, which is diazotized and coupled with N-(1 naphtyl)-ethylene

         The P = 0 compound of azinphos-ethyl and azinphos are
    co-determined with the method.

         Parathion and 4-nitrophenol do not interfere with the

         The limit of detection of the method is about 0.1-0.05 ppm.

         The recoveries by the colorimetric method (Meagher et al., 1960)
    were found to be similar to those obtained with GLC methods (Wagner,

                                       Recovery %
    Crop           Added ppm
                                       GLC       Colorimetry
    potato         0.1                 86        100
                   0.2                 93        99

    citrus         0.1                 76        72
                   0.2                 79        82

    TLC method

         Kirchhof (1970) developed a thin layer chromatographic separation
    of azinphos-ethyl, azinphos-methyl and their P = 0 analogues on silica
    gel coated plates combined with the colorimetric method of Miles

         The limit of determination of the method on apples, lettuce,
    kohlrabi and onions is 0.1-0.2 µg for the parent compounds and their
    P = 0 metabolites alone or in combination.

         The method does not require a special clean-up procedure. There
    is no interference from other insecticides, fungicides, herbicides or
    plant constituents.

    GLC method

         Residues of azinphos-ethyl, azinphos and their P = 0 analogues
    can be determined by gas chromatography with a high degree of
    sensitivity and specificity.

         Especially GLC methods utilizing a phosphorous-specific detector
    e.g. a modified flame ionization detector (thermionic detector) proved
    to be particularly suitable for regulatory purposes.

         Simultaneous GLC determination of azinphos-ethyl and its P = 0
    analogue in soybeans is described by Olson (1969). Azinphos is also

         Following extraction of the plant samples (green plants, dry
    beans and vines) with chloroform, interfering plant constituents are
    precipitated. The resultant extract is directly injected into the

         Under the given conditions azinphos, azinphos-ethyl
    and the P = 0 analogue of azinphos-ethyl are identified by their
    retention times which are 13.3, 17.3 and 15 minutes respectively.

         The limit of determination in this rapid procedure is about 0.005

         A similar procedure for GLC analysis of azinphos-ethyl and
    azinphos in cotton is described by Olson (1969a and b).

         Other organophosphorous compounds which may be used in cotton,
    such as diazinon, disulfoton and its sulfoxide and sulfone, demeton
    and its sulfoxide and sulfone, malathion and malaoxon did not
    interfere with the determination of azinphosethyl, azinphos and their
    P = 0 metabolites.

         A similar GLC method for determination of azinphos-ethyl,
    azinphos and their P = 0 metabolites in cigarette smoke is described
    by Olson (1969c).

         A method for the gas chromatographic determination of residues of
    azinphos-ethyl, azinphos-methyl and their P = 0 analogues in milk is
    described by Hunt et al. (1970). The extraction procedure corresponds
    to that of Adams et al. (1966). The sensitivity of this method for the
    determination of azinphos-methyl and the -ethyl analogue in milk
    samples is about 0.04 ppm and for the P = 0 analogue of
    azinphos-methyl about 0.06 ppm.

         New and generally applicable procedures for the extraction of
    residues of carbaryl, malathion, phosphamidon, azinphos-methyl and
    parathion from plant material are described by Watts (1971). The three
    described procedures which consist of sample blending with
    acetonitrile or ethyl acetate and an exhaustive Soxhlet extraction
    procedure using 10% methanol in chloroform, were compared. They were
    all found to give very good recoveries.

    National tolerances
        Australia                     fruit          2.0
                                  vegetables     1.0
                                  cereals        1.0
                                  potatoes       0 (at or about limit of detection)

    Belgium                       fruit          0.4
    azinphos-ethyl and
    -methyl together              vegetables     0.4
                                  potatoes       0.05

    Fed. Rep. of Germany          fruit          0.4
    azinphos-ethyl and
    -methyl together              vegetables     0.4 (except root vegetables)

                                  celeriac       0.4
                                  other food
                                  crops          0.05

    azinphos-ethyl and
    -methyl together                             0.4

    azinphos-ethyl and
    -methyl together              fruit crops    0.4
                                  vegetables     0.4 (except potatoes)
                                  potatoes       0.05

    azinphos-ethyl and            fruit crops
    -methyl together              incl.
                                  grapes         0.4
                                  vegetables     0.4

    South Africa                  fruit,
                                  vegetables     2

         Azinphos-ethyl is a non-systemic organophosphorus insecticide
    with contact action as well as stomach poison action used on a
    considerable scale in many countries on a relatively wide range of

         The main uses are foliar applications on field crops, such as
    cotton, sugarbeet, fruit and vegetables against a wide range of

         Technical azinphos-ethyl contains a minimum of 92% of the pure
    compound. The impurities in the technical material are known.

         Azinphos-ethyl is marketed in the form of wettable powders,
    emulsifiable liquids and as a ULV formulation.

         The concentration/rates of application vary, depending on pest,
    crop and method of application; normal application rates are
    250-1000 g/ha.

         The residue data available were obtained from different countries
    and regions with different climatic and pest conditions. The data
    presented for azinphos-ethyl including the P = 0 analogue are, with
    few exceptions, representative of those likely to result from good
    agricultural practice.

         Limited information is available on the fate of residues in
    plants. The residues which may occur in food of plant origin,
    following recommended directions for use and recommended pre-harvest
    intervals consist largely of the parent chemical and to a small extent
    of the P = 0 analogue. The residue may contain up to 10% of the P = 0

         Information considered provided a comparison between the nature
    and fate of azinphos-ethyl and its methyl analogue. The only
    noticeable difference is the greater persistence of the P = 0 analogue
    of the azinphos-ethyl. The P = 0 analogue is not detected at harvest
    following the use of azinphos-methyl.

         Only limited information is available on the rate of decrease of
    the residue of azinphos-ethyl and the P = 0 analogue in crops during
    storage and processing, including household cooking. Information was
    presented on the extent of carry over of residues in tobacco smoke
    following application to tobacco.

         Extensive data was available from supervised trials on
    cauliflower, kohlrabi, savoy cabbage, white cabbage, french beans. It
    was considered that a sufficient range of vegetable crops had been
    studied to enable recommendations to be made for vegetables as a

         Little information is available on azinphos-ethyl in food in
    commerce. A rapid and sensitive colorimetric method is described for
    the determination of azinphos-ethyl and the P = 0 analogue together.
    The method is specific for the benzotriazinol group and thus
    azinphos-ethyl and azinphosmethyl cannot be determined separately.

         Gas chromatographic procedures are available for specific
    determination of azinphos-ethyl and the P = 0 analogue. Appropriate
    extraction and clean-up procedures in food products of plant and
    animal origin are available. These methods are suitable for regulatory


         The following tolerances are recommended for azinphosethyl and
    its P = 0 metabolite expressed as azinphos-ethyl.


    Commodity                   Tolerance      Pre-harvest intervals on
                                (ppm)          which recommendations are
                                               based (days)

    Tomatoes                    1              14 (outdoors)

    Apples, pears               0.5            21

    Vegetables, except
      tomatoes and potatoes     0.5            14-21

    Soybeans (dry)              0.2            14-21

    Potatoes                    0.05a          14

    Cotton seed, rape seed      0.05a          14


    a At or about the limit of determination

    N.B.  In those cases where a mixture of residues of azinphos-ethyl
    and azinphos-methyl occurs together on a commodity, except  tomatoes,
    the total residue of both compounds including their P = 0 analogues
    may not exceed the levels recommended for azinphos-methyl. In case of
    tomatoes the total residue should not exceed the level recommended
    above for azinphos-ethyl, 1 ppm.


    Required (before an acceptable daily intake can be estimated)

    1.   Long-term studies to investigate chronic toxicity and

    2.   Studies to identify metabolites in plants and animals.

    3.   Studies to investigate the toxicity of metabolites.

    4.   Studies to detect effects on reproduction.

    5.   Studies to detect teratogenic activity.


    1.   Additional information on the nature of terminal residues
         in plants, animals and their products.

    2.   Data on disappearance of residues during storage and
         cooking of vegetables and fruits.


    Abbot, D. C., Crisp, S., Tarrant, K. R. and Tatton, J. O'G.
    1970                Pesticide residues in the total diet in England
                        and Wales, 1966-1967. III. Organophosphorous
                        pesticide residues in the total diet. Pestic. Sci
                        1: 10-13

    Adams, J. M. and Anderson, C. A. Spectrophotofluormetric
    1966                method for Guthion residues in milk and animal
                        tissues. J. Agric. Fd. Chem. 14: 53-55

    Anderson, C. A. A Comparison of the Residue Decline Rates
    1963                for Guthion and Ethyl Homolog on Alfalfa, Apples
                        and Lespedezza. Chemagro Report No. 10 394

    Anon. Pharmacokinetic studies with 14C-labelled Gusathion
    1973                A and Gusathion M (provisional results)
                        Unpublished report from Isotopen-Institut,
                        submitted by Bayer A.G.

    Ben-Dyke, R., Sanderson, D. M. and Noakes, D. N. Acute
    1970                toxicity data for pesticides. World Review of Pest
                        Control, 9: 119-127

    Doull, J. and Root, M. The Effect of Diets containing Ethyl
    1960                Guthion on Rats. Unpublished report from
                        University of Chicago

    Doull, J., Root, M. and Cowns, J. Determination of the safe
    1963                dietary level of Ethyl Guthion for dogs.
                        Unpublished report from University of Chicago

    Dubois, K. P. The Acute Toxicity of Ethyl Guthion in
    1963                Combination with Four Other Organic Phosphates.
                        Unpublished report from University of Chicago

    Dubois, K. P. and Raymund, A. B. The Acute Toxicity of Ethyl
    1960a               Guthion in Combination with Other
                        Anticholinesterase Agents. Unpublished report from
                        University of Chicago

    Dubois, K. P. and Raymund, A. B. The Subacute Toxicity of
    1960b               Ethyl Guthion to Rats. Unpublished report from
                        University of Chicago

    Dubois, K. P., Schmalgemeier, D. and Leighton, L. B.
    1959                Studies on the Toxicity and Anticholinesterase
                        Action of Ethyl Guthion. Unpublished report from
                        University of Chicago

    Grasso, P. Results of histological examination of brain,
    1969                spinal cord and a peripheral nerve from hens
                        treated with Ethyl-gusathion for 30 days.
                        Unpublished report from British Industrial
                        Research Association, submitted by Bayer A.G.

    Hunt, L. M. and Gilbert, B. N. Simultaneous determinations of
    1970                azinphos-ethyl, azinphos-methyl and its oxygen
                        analogue by gas liquid chromatography. Bull. of
                        Env. Cont. and Tox. 5: 42-46

    Kimmerle, G. Active substance R1513 (Ethyl Gusathion;
    1959                No. 2078). Unpublished report from Bayer A.G.

    Kimmerle, G. Ethyl-Gusathion. Unpublished report from
    1960                Bayer A.G.

    Kimmerle, G. Gusathion A/Antidotwirkung und Potentzierung.
    1966a               Unpublished report from Bayer A.G.

    Kimmerle, G. Gusathion A-Wirkstoff (R 1513;  Ht. - Nr. 3651).
    1966b               Unpublished report from Bayer A.G.

    Kimmerle, G. Äthyl-Gusation/Subchronische Neurotoxizitäts
    1968                versuche bei Hühnern. Unpublished report from
                        Bayer A.G.

    Kimmerle, G. and Lorke, D. Toxicology of insecticidal
    1968                organophosphates. Pflanzenschutz-Nachrichten,
                        Bayer, 21: 111-142

    Kirchhoff, J. Spezifischer dünnschichtchromatographischer
    1970                Nachweis von Gusathion-Rückständen in Pflanzen
                        extrakten. Pflanzenschutznachrichten, Bayer, 23:

    Krause, Ch. und Kirchhoff, J. Organophosphatrückstände auf
    1969                Marktproben von Obst and Gemüse sowie auf
                        Getreideerzeugnissen. Deutsch. Pflanzenschutzd.
                        (Braunschweig), 21, 1969: 81-84

    Lorke, D. and Kimmerle, G. The Action of Reactivators in
    1969                Phosphoric - Acid-Ester Poisoning. Naunyn
                        Schmiedebergs Arch. Pharmak. exp. Path. 263: 237

    Löser, E. BAY 16 259/Subchronische toxikologische
    1969                Untersuchungen an Ratten. Unpublished report from
                        Bayer A.G.

    Mawdesley-Thomas, L. E. and Urwin, C. Pathology Report of
    1969                BAY 16 259. Sub-chronic Toxicity Study in Rats
                        Administered over Three Months. Unpublished report
                        from Huntingdon Research Centre, submitted by
                        Bayer A.G.

    Meagher, W. R., Adams. J. M., Anderson, C. A. and Macdougall, D.
    1960                Colorimetric determination of Guthion residues in
                        crops. J. Agric. Fd. Chem., 8: 282-286

    Miles, J. R. W. A new colorimetric method for determination
    1964                of residues of Guthion and Ethyl Guthion and their
                        oxygen analogs. J.A.O.A.C. 47: 882-885

    Möllhoff, E. Kolorimetrische Bestimmung von Azinphos-äthyl. 1969
                        Rückstands analytik von Pflanzenschutmitteln.
                        (DFG), Verlag Chemie GmbH, Weinheim/Bergstr.

    Olson, T. J. Investigation of the possible metabolism of
    1969                Ethyl-Guthion on crops. Chemagro Report No. 25
                        151 (unpublished)

    Olson, T. J. Determination of residues of Guthion M-E in
    1969a               soybeans by thermionic emission gas
                        chromatography. Chemagro Report No. 25 152

    Olson, T. J. A confirmatory gas chromatographic procedure for
    1969b               the Guthion M-E residue method. Chemagro Report
                        No. 25 911 (unpublished)

    Olson, T. J. A study of the possible interferences or other
    1969c               pesticides with the analytical method for Guthion
                        M-E in cotton. Chemagro Report No. 25 912

    Olson, T. J. Determination of Guthion M-E residues in
    1969d               cigarette smoke. Chemagro Report No. 25 121

    Olthoff, P. D. A. and de Mey, R. C. H. Residues of azinphos
    1973                ethyl on potatoes. Report No. 3954 Central
                        Institute for Nutrition and Food Research,

    Schumann, S. A. and Anderson, R. J. Determination of Guthion
    1965                M-E residues in clover by electron capture gas
                        chromatography. Chemagro Report No. 16 571

    Sherman, M., Herrick, R. B., Ross, E. and Chang, M. T. Y.
    1967                Further Studies of the acute and subacute toxicity
                        of Insecticides to Chicks, Toxicol. and Appl.
                        Pharmacol. 11: 49-67

    Wagner, Kl. Report of Bayer A.G., Leverkusen (Pflanzenschutz
    1973                AT/Biologische Forschung, Institut für
                        Rückstandsanalytik) (unpublished)

    Watts, R. R. Extraction efficiency study - Examination of three
                        procedures for extracting 14C-labeled and
                        unlabeled residues of organophosphorus pesticides
                        and carbaryl from bean leaves and kale. J.A.O.A.C.
                        54: 953-958

    See Also:
       Toxicological Abbreviations
       Azinphos-ethyl (Pesticide residues in food: 1983 evaluations)