DIAZINON           JMPR 1975


         At the 8th Session of the Codex Committee on Pesticide Residues a
    request was made for a recommended maximum residue limit for diazinon
    in milk and milk products: (ALINORM 76/24 para. 89).


         Diazinon is used as a spray or dip for the control of lice and
    ticks in cattle. It may also be used in dairy barns for the control of
    flies and similar pests. It is also used on pasture and forage crops
    for the control of a range of insect pests. When used as a spray on
    cattle the concentration is 0.05 - 0.1% active ingredient.


         The results of investigations on the metabolic fate of diazinon
    in mammals were summarized in the Report of the 1969 Joint Meeting
    (FAO/WHO 1970). These show that when diazinon is fed to lactating
    cows, even at concentrations as high as 1000 ppm in the ration, no
    residues appear in milk, meat, or tissues other than fat. Even then,
    the fat from the animals receiving 1000 mg/kg in their ration
    contained only 0.2 mg/kg of diazinon.

         New data were provided by Switzerland in response to the request
    made by the Codex Committee on Pesticide Residues. Reports of
    experiments carried out in 1971 (Ciba-Geigy 1971) contain the results
    of residue analyses for diazinon and diazoxon in milk samples from
    eight cows, which were sprayed four times at weekly intervals with
    0.05 or 0.1% active ingredient. The milk was analysed daily after each

         The results which are summarized in Table 1 show the residue
    values to vary considerably from cow to cow and between treatments of
    individual cows. The residue levels in milk from cows treated with
    0.1% diazinon are somewhat higher than in milk from those treated with
    0.05%. The maximum residue levels reported were 0.57 mg/kg and 0.39
    mg/kg for the 0.1% and 0.05 a.i. treatments respectively and these
    were found shortly after treatment. These residue levels decreased to
    0.02 mg/kg or less within about 6 days of spraying.

         Diazoxon was not detected in any samples of milk by methods
    capable of determining 0.005 mg/kg.

         Bourne and Arthus (1967) used 15 lactating cows in an experiment
    to determine the presence or absence of diazinon in milk following
    dermal application. Five cows were treated for 4 consecutive days with
    2% diazinon dust at a rate of 60g per cow; 5 received diazinon applied
    from a backrubber for 10 consecutive days and 5 were untreated. Milk
    samples were analysed at 12 hours and 1, 3, 5, 10 and 15 days after
    the initial application of diazinon.

         The milk was analysed by the method of Margot and Stammbach
    (1964) with a limit of determination of 0.05 mg/kg. Milk from 3 of the
    cows treated with the diazinon dust and 2 of the cows treated by the
    backrubber method contained detectable quantities of the insecticide
    12 hours after treatment. The residues persisted in the milk from two
    of the cows treated with the 2% dust for the first 24 hours after the
    initial application. The amount only just exceeded the limit of
    determination, the highest value reported being 0.135 mg/kg. Milk from
    untreated cows gave a reaction which was calculated to be equivalent
    to 0.04 mg/kg apparent diazinon.

         Mathysse and Fisk (1968) measured the residue of diazinon and
    other insecticides in cows' milk following treatment similar to those
    used in ectoparasite and fly control. Their studies included the
    measurement of residues in the milk of individual cows after topical
    application. Very small amounts of short-lived residues were found in
    milk after spraying cows with a large volume of 0.06% diazinon
    suspension. Maximum apparent diazinon was 0.33 mg/kg 1 day after a
    second spray treatment. By 7 days, apparent diazinon residues were the
    same as in milk from untreated cows.

         Much lower residues of diazinon in milk were found by Hastie
    (1963) who reported 0.04 - 0.05 mg/kg 1 day after cows were sprayed
    with 0.05 and 0.1% diazinon emulsion and less than 0.01 mg/kg within 2

         Formica (1973) determined the residue of diazinon in the milk of
    sheep following dipping in emulsions containing 0.04 and 0.02% active
    ingredient. Using a GLC method capable of determining 0.01 mg/kg in
    milk it was found that residues of diazinon decrease within 15 days
    after dipping from 0.17 to less tho 0.01 mg/kg (when treated with
    0.04% a.i.) or from 0.09 to less than 0.01 mg/kg (when dipped in 0.02%

         Leschchev, et al, (1972) report trials in which two lactating
    cows were sprayed with solutions containing 0.2% a.i. diazinon at the
    rate of 3 litres/animal. Samples of milk taken after the first milking
    after treatment were analysed by GLC methods. Peak concentrations were
    reached after 6 hours (0.65 and 0.39 mg/kg from individual cows).
    Three days after treatment the residue level had declined to
    0.036 mg/kg. Four days after treatment the residue levels were below
    the limit of determination (below 0.001 mg/kg). The levels were
    greatly different between the two cows.

         Bull and McDougall (1974) determined the level and fate of
    diazinon residues in milk and milk products from a dairy herd sprayed
    with 0.5% a.i. diazinon emulsion at the rate of 10 litres/animal. They
    found that the maximum concentrations occurred in the first milking
    after treatment and in bulked whole milk from the treated herd the
    maximum concentration was 0.25 mg/kg. Residues in whole milk returned
    to pre-treatment levels by the 4th milking. Cream and butter prepared
    from the milk of the treated herd contained 2.4 mg/kg and 4.5 mg/kg
    respectively at the first milking and declined to 0.3 mg/kg in butter
    after the 4th milking. Only a trace of diazinon (less than 0.04 mg/kg)
    was detected in skim milk made from the whole milk from the first
    milking after treatment. The whole milk excreted by the herd contained
    4% fat. Cream contained 59% fat and butter 81.6%. Skim milk contained
    0.07% fat.

         Results of the study by Bull and McDougall are summarized in
    Tables 1 and 2.


    In processing

         Leschchev et al, (1972) showed that pasteurization (90C for 15
    minutes) had no effect in the level of diazinon in whole milk.
    Pasteurization at 70C for 30 minutes reduced the level by 17%.

         Cooking (details not given) reduced the diazinon concentration by
    53% and "acidification of milk" reduced the concentrations by 65%.

         Bull and McDougall (1974) showed that all the diazinon in whole
    milk is in the fat and that it all carries over into the butter. There
    is an apparent loss owing to interference which produces artificially
    high figures during the analysis of whole milk.


         The data previously considered show that there is no reasonable
    expectation that diazinon residues in animal feed will be transferred
    to milk. New data received by the Meeting from spraying trials carried
    out in USA, Switzerland, USSR and Australia revealed that significant
    quantities of diazinon appear in milk following topical application.
    The quantity excreted varied greatly from animal to animal and from
    one treatment to the next on the same animal.

    TABLE 1.  ppm diazinon in milk, skim milk and butter of individual
              cows treated with nucidol 20 at 0.05% w/v concentration


                                Whole Milk

                                  Cow No.
                                                                          Skim Milk       Butter
    Milkings        151     233     238     248     249       Mean       (Composite)    (Composite)

    Pretreatment                                              0.03          0.02           0.08

    1st milking     0.31    0.25    0.21    0.13    0.19    0.220.08       0.03           5.2

    2nd milking     0.14    0.05    0.05    0.03    0.04    0.060.03       0.02           1.7

    3rd milking     0.08    0.06    0.05    0.06    0.04    0.060.02       ----           0.84

    4th milking     0.03    0.02    0.05    0.02    0.02    0.030.01       ----           0.26

    10th milking    0.02    0.02    0.05    0.02    0.01    0.020.02       ----           0.05

    TABLE 2.  ppm diazinon in milk, skim milk, butter and cream from the
              bulk storage vessel after treating the herd with nucidol 20
              at 0.05% w/v concentration


                               Residue p.p.m. Diazinon

    Bulkings               Milk    Milk    Cream   Butter

    Pre-treatment          0.03    0.02    0.09    0.08

    1st milking            0.25    0.04    2.4     4.5

    1st & 2nd milkings     0.15    0.03    2.1     2.6

    3rd milking            0.06    0.02    0.57    0.60

    3rd & 4th milkings     0.04    0.02    0.26    0.30

         It is apparent that if a herd was treated the level in the
    blended milk would be much less than the maximum amount excreted by
    one cow. In keeping with the recommendations for establishing maximum
    residue levels in milk and milk products (FAO/WHO 1972a) it is
    appropriate to establish the maximum residue limit in the knowledge
    that milk from treated herds will be bulked, and blended with milk
    from untreated cows before going into commercial channels.

         It has been demonstrated that diazinon partitions principally
    into the lipid fraction of animal tissues and it can be expected that
    the bulk of the residue will be located in the milk Lit, the
    concentration being greatly magnified by the preparation of butter.


         The following maximum residue limit is additional to
    recommendations made previously and is based on the measurement of the
    diazinon only:

         Milk and Milk products (fat basis) - 0.5 mg/kg


    Bourne, J.R., and Arthur B.W. (1967) Diazinon residues in milk of
    dairy cows. J. Econ. Entom. 60 (2):402-405.

    Bull, M.S. and McDougall, K. (1974) Determination of diazinon residues
    in milk and milk products from lactating cows following treatment with
    diazinon 20EC. Ciba-Geigy Australia Ltd. Report 74/4/440.

    Formica, G. (1973) Residues in sheep milk after dipping animals in
    diazinon. Ciba-Geigy Agrochemicals (Basle) Report RVA/32/73.

    Hastie, B.A. (1963) Diazinon residues. Geigy (Australasia) Multilith.
    July 1963, 17 pages.

    Leschchev, V.V., Kan, P.T., and Talanov, C.A. (1972) Residues of
    dursban and diazinon in cows milk. Veterinarija 1972 Vol. 10, 114-115
    (in Russian).

    Margot, A., and Stammback, K. (1964) In Analytical Methods for
    Pesticides and Food Additives, Ed. by Gunter Zweig, Academic Press NY.
    Vol.II p. 109-124.

    Mathysse, J.G., and Fisk, D. (1968) Residues of diazinon coumaphos,
    Ciodrin, methoxychlor and rotenane in cows' milk from treatments
    similar to those used for ectoparasite and fly control on dairy
    cattle. J. Econ. Entom. 61 (2):1394-98.

    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 (AGP:1970/M/12/1)
       Diazinon (Pesticide residues in food: 1979 evaluations)
       Diazinon (Pesticide residues in food: 1993 evaluations Part II Toxicology)
       Diazinon (JMPR Evaluations 2001 Part II Toxicological)