IPCS INCHEM Home


    PESTICIDE RESIDUES IN FOOD - 1984


    Sponsored jointly by FAO and WHO






    EVALUATIONS 1984




    The monographs



    Data and recommendations of the joint meeting
    of the FAO Panel of Experts on Pesticide Residues
    in Food and the Environment and the
    WHO Expert Group on Pesticide Residues
    Rome, 24 September - 3 October 1984

    Food and Agriculture Organization of the United Nations
    Rome 1985

    AMITRAZ

    Explanation

         Amitraz was reviewed by the 1980 JMPR. 1/ A temporary ADI of
    0.0005 mg/kg was estimated and a number of temporary MRLs proposed.
    Additional residue data on whole olives from supervised trials were
    required by 1984 and additional residue data on citrus fruit and
    further trials on hops, eggplant and onions were considered desirable.

         The present meeting was informed that the use of amitraz on
    olives has not been developed commercially. Residues data on pears and
    citrus were made available, as well as new information on plant
    metabolism.

    RESIDUES IN FOOD AND THEIR EVALUATION

    USE PATTERN

         Amitraz is registered in a number of territories for the control
    of various mite species of citrus (Panonychus citri, Tetranychus
    spp., Phyllocoptruta oleivora). Cultural practices and agronomic
    needs differ among these territories. For example, higher rates of
    amitraz are required to control infestations of Tetranychus spp.
    than for other mite species. Similarly, application volumes vary
    depending on local practice and the number and size of trees. Thus,
    approved uses are often expressed differently in the different
    territories. These have been standardized in terms of maximum spray
    concentration and an approximate equivalent rate of amitraz per
    hectare in Table 1.

         The use of amitraz has been approved recently in the Netherlands
    on strawberries for the control of spider mite at 38 g/100 1 up to
    flowering and after the last picking (1981), and on eggplant,
    peppers and tomatoes in glasshouses for the control of spider mite at
    76 g/l 1000m2 by swingfog or pulsfog only, with a three-day interval
    between last application and harvesting (1981/82). Its use on pig,
    cattle and sheep has been approved since 1980.

              

    1/  See Annex 2 for FAO and WHO documentation


        TABLE 1.  Registration Status of the Use of Amitraz on Citrus

                                                                                                    

                                                            Approved application rates
                                  Withholding                                                       
                                    period            Spray concentration        Approximate
    Territory                       (days)                 (%a.i.)                g a.i./ha
                                                                                                    

    Cyprus                            14                     0.04                    600
    Ecuador                           14                     0.12                    500
    Iran                              NA                     0.02                    400
    Italy                             14                     0.04                    400
    Japan                             14                     0.02                  1 200
    Malaysia                           7                     0.04                    400
    Morocco                           28                     0.01                  1 200
    Republic of Korea                 NA                     0.02                    900
    Spain                              7                     0.04                    400
    Taiwan province of China          14                     0.02                    400
    Turkey                            28                     0.04                    400
                                                                                                    
    

    RESIDUES RESULTING FROM SUPERVISED TRIALS

    Apples and Tomatoes

         Apple and tomato samples from amitraz trials were analysed for
    amitraz and its metabolite BTS 27 271. An analytical procedure was
    used that involved the conversion of amitraz to BTS 27 271 and the
    assay of the total BTS 27 271 residue. The maximum residue of BTS
    27 271 in apples 28 days after a single spray application of amitraz
    was found to be 0.24 mg/kg. In tomatoes, three days after a single
    spray application of amitraz, the maximum residue of BTS 27 271 was
    found to be 0.46 mg/kg (Table 2).

    Citrus

         Residues on citrus grown in the United States have been
    determined by the "total residue" method, in which all residues
    containing the 2,4-dimethyl-analine moiety are measured and the
    residue expressed as amitraz equivalent. (The residue method
    recommended by JMPR/Codex determines the sum of amitraz and its
    metabolite N-(2,4-dimethylphenyl)-N'-methylformamidine (BTS 27 271).
    Residue values determined by the "total amitraz" method may be
    converted to equivalent values determined as BTS 27 271 by dividing by
    a factor of 1.8.)

    Grapefruit

         Following one to three applications of amitraz at up to
    24 oz/acre (1 lb/acre = 1.12 kg/ha), mean residues in grapefruit over
    a period of 1 to 14 days ranged from <0.05-1.04 mg/kg, with an 
    over-all mean of 0.49 mg/kg (Table 3).

    Lemon

         Following one or two applications of amitraz at a rate of
    24 oz/acre, mean residues in lemons over a period of 1 to 12 days
    ranged from 0.44 to 1.23 mg/kg in lemons, with an over-all mean of
    0.81 mg/kg (Table 4).

    Lime

         Following one to three applications of amitraz at up to
    5 oz/acre, mean residues in limes over a period of 1 to 14 days
    ranged from 0.16 to 2.11 mg/kg, with an over-all mean of 0.84 mg/kg
    (Table 5).

    Tangerine and Tangelo

         Following a single application of 24 oz/acre of amitraz to
    tangerines, mean residue levels over a period of 1 to 12 days were
    0.79 to 1.49 mg/kg, with an over-all mean of 1.16 mg/kg. For tangelo,
    following one or two applications, the equivalent residue levels were
    0.73 to 1.85 mg/kg and 0.86 mg/kg, respectively (Table 6).


        TABLE 2.  Amitraz Residues in Tomatoes from Supervised Trials, The Netherlands

                                                                                                            

                                   Application
                                                            
    Year         No.           Rate            Formulation       Residues1               Reference
                               (kg a.i./ha)                      (mg/kg)
                                                                                                            

    1974         1             1.14            40                0.40 (0.29-0.46)        Goodall &
                                                                                         Somerville, 1974

    1974         1             1.14            40                0.27 (0.17-0.36)        Greve &
                                                                                         Hogendoorn, 1975

    1979         1             76 g a.i./      pulsfog           0.11 (0.08-0.17)        Netherlands,
                               1 000 m2                                                  1979

    1980         1             80 g a.i./      pulsfog           0.15 (0.10-0.21)        )
    (glass-                    1000 m2                                                   ) van Adrichem &
    house)                                                                               ) Vogelezang,
                                                                                         ) 1981
    1980         1             81 g a.i./      swingfog          0.05 (0.02-0.07)        )
    (glass-                    1 000 m2                                                  )
    house)                                                                               )
                                                                                                            

    1  Measured three days after application; determined and expressed as 
       N-2,4-dimethylphenyl-M-methylformamidine.

    TABLE 3.  Amitraz Residues in Grapefruit from Supervised Trials, United States

                                                                                                        

              Application                 
    Rate           No.      Spray volume     Interval        Residues (mg/kg)           Reference
    (oz a.i./               (gal/acre)       (days)       Range           Mean
    acre)
                                                                                                        

    4.5                         300             1         0.17 - 0.19     0.18          Ford, 1981b
                                                8         0.10 - 0.15     0.13
                                               15         0.11 - 0.12     0.11
                                               29         0.07 - 0.08     0.08
                                               43         0.06 - 0.07     0.07

    9                           300             1         0.33 - 0.38     0.36          Ford, 1981b
                                                8         0.18 - 0.27     0.23
                                               15         0.15 - 0.18     0.17
                                               29         0.12 - 0.16     0.14
                                               43         0.09 - 0.13     0.11

    24                        1 800             7         0.18 - 0.37     0.28          Upjohn &
    7.5                         100             1                         0.32          Boots,
                                                7                         0.18          1974 - 1981
                                               14                         <0.05
    15                          100             1                         0.61
                                                7                         0.43
                                               14                         <0.05

    24             3                            1         0.82 - 1.27     1.04          Ford, 1981d
                                                7         0.71 - 1.09     0.98
                                               14         0.84 - 1.02     0.92
                                                                                                        

    Note: 1 lb/acre = 1.12 kg/ha; 1 U.S. gal/acre = 9.36 l/ha

    TABLE 4. Amitraz Residues in Lemons from Supervised Trials, United States

                                                                                                        

              Application                 
    Rate           No.      Spray volume     Interval        Residues (mg/kg)           Reference
    (oz a.i./               (gal/acre)       (days)       Range           Mean
    acre)
                                                                                                        

    48                         1 200             1        1.86 - 1.93     1.90          Ford, 1981a
                                                 7        1.17 - 1.37     1.26
                                                14        1.11 - 1.15     1.13
                                                28        0.73 - 0.79     0.76
                                                56        0.38 - 0.41     0.40
                                               112        0.12 - 0.20     0.17

    24                           180             1        1.14 - 1.24     1.19          Ford 1981d
                                                 7        0.99 - 0.99     0.99
    24             2             180             1        1.19 - 1.26     1.23
                                                 7        0.66 - 0.93     0.80
    24             2              40             1        0.57 - 1.04     0.81
                                                12        0.34 - 0.70     0.52
    24             2             500             1        0.68 - 0.81     0.73
    24             2           1 200             1        0.59 - 0.64     0.62
                                                 7        0.40 - 0.47     0.44
                                                                                                        

    TABLE 5.  Amitraz Residues in Limes from Supervised Trials, United States

                                                                                                        

              Application                 
    Rate           No.      Spray volume     Interval        Residues (mg/kg)           Reference
    (oz a.i./               (gal/acre)       (days)       Range           Mean
    acre)
                                                                                                        

    7.5                          250            86                        <0.05         Ford, 1981c
    15                                          86                        <0.05

    24                            40             1        2.07 - 2.15     2.11
                                                 7        1.18 - 2.17     1.68

    7.5                          100             1                        0.41
                                                 7                        0.27
                                                14                        0.16

    15                                           1                        0.64
                                                 7                        0.28
                                                14                        0.23

    24             3              40             1        1.37 - 2.07     1.72
                                                12        0.60 - 1.11     0.86
                                                                                                        

    TABLE 6.  Amitraz Residues in Tangerines and Tangelos from Supervised Trials, United States

                                                                                                        

              Application                 
    Rate           No.      Spray volume     Interval        Residues (mg/kg)           Reference
    (oz a.i./               (gal/acre)       (days)       Range           Mean
    acre)
                                                                                                        

    TANGERINE

    24                            40             1        0.86 - 2.11     1.49          Upjohn &
                                                12        0.63 - 0.85     0.74          Boots,
                                                                                        1981b

    TANGELO

    24                           500            97        0.26 - 0.38     0.32          Upjohn &
    24                            40             1        1.13 - 2.57     1.85          Boots,
                                                12        0.73 - 0.97     0.85          1981a
    24             2             500             1        0.65 - 1.07     0.86
                                                14        0.72 - 0.73     0.73
                                                                                                        
    

    Orange

         The application rate of 24 oz/acre is that approved under an
    experimental use permit in the United States and for which a temporary
    tolerance of 2 mg/kg has been established. At this rate, the range of
    residue values in oranges over a period of 1 to 7 days following a
    single application was 0.18 to 1.25 mg/kg, with an overall mean of
    0.48 mg/kg. Following two applications, the equivalent values were
    0.32 to 1.01 mg/kg and 0.59 mg/kg. Following three applications, the
    range of mean values over a period of 1 to 21 days was 0.26 to
    2.20 mg/kg, with an overall mean of 0.188 mg/kg (Table 7).

         Residues of amitraz in oranges, grown in the United States,
    treated at higher rates (i.e. 40 oz/acre or 2.8 kg/ha) were within the
    range of expected values, as were those crops treated at lower rates
    (Table 8).

         The analytical method used to determine residues in or on oranges
    grown in Japan measured amitraz and its metabolite BTS 27 271
    separately. Studies undertaken in Japan are summarized in Tables 9 and
    10. In the former, the data indicate that the majority of the residues
    are in the peel, with residues being predominantly present as the
    metabolite BTS 27 271. The second study (Table 10) confirms the low
    residues (generally less than 0.01 mg/kg of the parent compound
    following a preharvest interval of 15 days.)

         Two studies were conducted in China in 1982 and 1983 to determine
    the persistence and residue distribution of amitraz in oranges. The
    first study determined the residues of amitraz from trials conducted
    on oranges grown in Guangdong. In 1983 this study was repeated in
    Guangdong and Guangxi. The method of analysis used to measure residues
    was the same as that used in the United States, which determines
    amitraz and its metabolites containing the 2,4-dimethylaniline moiety.
    These studies are unpublished but are summarized in Tables 11 and 12.
    These data confirm the general levels of amitraz residues found in
    other studies and their distribution within the fruit.

         The residues of 2,4-dimethylaniline (BTS 24 868) in two samples
    of commercially grown oranges were determined using an analytical
    method that had been initially developed for BTS 24 868 residues in
    pears. Peel and flesh were analysed separately. The recoveries of BTS
    24 868 from control oranges ('Valencia' and 'Maroc Late'), fortified
    at either 0.1 or 0.05 mg/kg, gave an over-all mean and standard
    deviation of 82.4  15.7 percent. Mean BTS 24 868 residues in the peel
    of control oranges fortified with 0.25 mg/kg of either amitraz, BTS
    27 271 or BTS 27 919 were found to range from 0.012 to 0.026 mg/kg
    (equivalent to 4.8 to 10.3 percent artefactual conversion of the
    parent compounds to BTS 24 868). Residues of BTS 24 868 in the flesh
    of oranges from the two commercial orchards analysed were below the
    limit of detection (0.003 mg/kg), as were the total amitraz-derived
    residues (limit of detection 0.025 mg/kg). Residues of BTS 24 868 in
    the peel of these oranges were 0.022 mg/kg (Grower 1) and 0.040 mg/kg


        TABLE 7.  Amitraz Residues in Oranges from Supervised Trials, United States

                                                                                                        

              Application1
                                          
    Rate           No.      Spray volume     Interval        Residues (mg/kg)           Reference
    (oz a.i./               (gal/acre)       (days)       Range           Mean
    acre)
                                                                                                        

                   1           1 900             1        0.11 - 0.50     0.26          Upjohn &
                                                 7        0.12 - 0.46     0.25          Boots
                   1           1 300             1        0.24 - 0.25     0.25          1974-1981
                                                 7        0.17 - 0.24     0.21
                   1             100             1        1.00 - 1.49     1.25
                                                 7        0.86 - 1.19     1.03
                   1             100             1        0.62 - 0.79     0.71
                                                 7        0.44 - 0.61     0.53
                   1             180             1        0.24 - 0.71     0.48
                                                 7        0.14 - 0.22     0.18
                   1           1 800             7        0.26 - 0.37     0.31
                   1           1 800             1        0.31 - 0.36     0.34

                   2             100             1        0.58 - 0.88     0.73          Upjohn &
                                                 7        0.39 - 0.71     0.55          Boots,
                   2           1 300             1        0.30 - 0.35     0.33          1974-1981
                                                 7        0.32 - 0.32     0.32
                   2             100             1        0.63 - 1.38     1.01
                                                10        0.47 - 0.76     0.62
                   2             180             1        0.60 - 0.71     0.66
                                                 7        0.40 - 0.53     0.47

                   3                             1        1.85 - 2.42     2.20          Ford, 1981c
                                                 7        1.13 - 1.54     1.46
                                                14        0.98 - 1.23     1.07
                                                21        0.68 - 1.54     1.11
                                                                                                        

    Table 7 (continued)

                                                                                                        

              Application1
                                          
    Rate           No.      Spray volume     Interval        Residues (mg/kg)           Reference
    (oz a.i./               (gal/acre)       (days)       Range           Mean
    acre)
                                                                                                        

                   3                             1        0.47 - 0.59     0.52
                                                 7        0.28 - 0.42     0.35
                                                14        0.38 - 0.42     0.40
                                                21        0.19 - 0.33     0.26
                   3                             1        0.57 - 1.37     0.88
                                                 7        0.52 - 1.32     0.82
                                                21        0.69 - 1.45     1.14
                   3                             1        0.60 - 0.80     0.73
                                                 7        0.37 - 0.74     0.55
                                                                                                        

    1 Rate of application was 24 oz a.i./acre in all trials

    TABLE 8.  Amitraz Residues in Oranqes from Supervised Trials, United States

                                                                                                        

            Application
                                 
    Rate            Spray volume         Interval          Residues (mg/kg)             Reference
    (oz a.i./       (gal/acre)           (days)         Range             Mean
    acre)
                                                                                                        

    19.8              1 000                 1           0.99 - 1.09       1.06          Ford, 1980
                                            7           0.69 - 0.92       0.79
                                           14           0.55 - 0.65       0.59
                                           27           0.38 - 0.46       0.42
                                           49           0.16 - 0.28       0.23
                                          119           0.10 - 0.14       0.11
                                          141           0.09 - 0.09       0.09

    40                1 000                 1           0.62 - 0.69       0.65          Ford, 1981a
                                            7           0.42 - 0.49       0.46
                                           14           0.34 - 0.48       0.40
                                           28           0.31 - 0.36       0.34
                                           58           0.27 - 0.34       0.31

    40                1 000                 1           1.67 - 1.94       1.79          Ford, 1981a
                                            7           1.16 - 1.35       1.25
                                           14           0.83 - 0.95       0.89
                                           28           0.48 - 0.54       0.52
                                           56           0.20 - 0.22       0.21

    40                1 000                 1           0.58 - 0.66       0.63          Ford, 1981a
                                            8           0.46 - 0.59       0.53
                                           15           0.49 - 0.52       0.51
                                           31           0.51 - 0.55       0.52
                                           57           0.41 - 0.49       0.45
                                                                                                        

    TABLE 8.  (continued)

                                                                                                        

            Application
                                 
    Rate            Spray volume         Interval          Residues (mg/kg)             Reference
    (oz a.i./       (gal/acre)           (days)         Range             Mean
    acre)
                                                                                                        

    19.8              1 000                 1           0.64 - 0.85       0.73          Ford, 1980
                                            8           0.50 - 0.53       0.51
                                           14           0.43 - 0.48       0.46
                                           28           0.26 - 0.31       0.29
                                           56           0.15 - 0.16       0.15
                                          112           0.06 - 0.08       0.07
                                          147           0.05 - 0.05       0.05

    4.5                 300                 1           0.19 - 0.27       0.25          Ford, 1981b
                                            8           0.10 - 0.15       0.13
                                           15           0.12 - 0.14       0.13
                                           29           0.09 - 0.12       0.10
                                           43           0.08 - 0.12       0.10

    9                   300                 1           0.39 - 0.45       0.41          Ford, 1981b
                                            8           0.23 - 0.34       0.28
                                           15           0.23 - 0.28       0.26
                                           29           0.13 - 0.16       0.14
                                           43           0.14 - 0.16       0.15
                                                                                                        

    TABLE 9.  Amitraz and BTS 27 271 Residues in Oranqes from Supervised Trials, Japan1

                                                                                                    

                                                  Residue (mg/kg) 2                Reference
    Interval        Compound                                                  
    (days)          analysed           Peel         Pulp         Whole fruit
                                                                                                    

    20              Amitraz            0.01         <0.007         <0.01           Takano,
                    BTS 27 271         0.77          0.176          0.35           1974

    30              Amitraz            0.01         <0.007         <0.01
                    BTS 27 271         0.46          0.116          0.19

    40              Amitraz            -             -              -
                    BTS 27 271         0.26          0.098          0.13

    50              Amitraz            -             -              -
                    BTS 27 271         0.08          0.073          0.07
                                                                                                    

    1  Spray concentration 0.02% amitraz.
    2  Residues of amitraz and BTS 27 271 analysed separately.

    TABLE 10.  Amitraz Residues in Oranges from Supervised Trials, Japan

                                                                                                   

    Spray          Part           No. of         Interval         Residue
    volume1        analysed       applications   (days)           (mg/kg)2           Reference
    (1/ha)                                                    Lab.A     Lab. B
                                                                                                   

    8 000          Flesh             0              -         <0.01     <0.01        Nissan &
                                     2             15         <0.01     <0.01        Boots,
                                     2             30         <0.01     <0.01        1972
                                     3              7         <0.01     <0.01
                                     3             15         <0.01     <0.01
                                     3             30         <0.01     <0.01

                   Peel              0              -         <0.01     <0.01
                                     2             15         <0.01      0.01
                                     2             30         <0.01      0.01
                                     3              7          0.09      0.10
                                     3             15          0.10      0.07
                                     3             30          0.02      0.02

    6 000          Flesh             0              -         <0.01     <0.01
                                     2             15         <0.01     <0.01
                                     2             30         <0.01     <0.01
                                     3              7         <0.01     <0.01
                                     3             15         <0.01     <0.01
                                     3             30         <0.01     <0.01

                   Peel              0              -         <0.01     <0.01
                                     2             15         <0.01     <0.01
                                     2             30         <0.01     <0.01
                                     3              7          0.08      0.08
                                     3             15         <0.01     <0.01
                                     3             30         <0.01     <0.01
                                                                                                   

    1  Spray concentration 0.01% amitraz.
    2  Residue determined as amitraz alone.

    TABLE 11.  Amitraz Residues in Oranges from Supervised Trials, China1

                                                                                                        

                                             Residues (mg/kg)
                    Interval                                                                            
    Applications    Days                Peel                      Pulp                Whole fruit
                                                                                                       
                                 Range       Mean         Range         Mean       Range        Mean
                                                                                                        

    1                  0         0.98-1.13   1.04         0.026-0.046   0.034      0.44-0.51    0,47
                      20         0.50-0.60   0.56         0.015-0.063   0.059      0.21-0.25    0.23
                      40         0.31-0.55   0.42         0.068-0.083   0.074      0.15-0.27    0.20

    2                  0         1.25-1.94   1.66         0.08-0.10     0.09       0.58-0.63    0.61
                       7         1.12-1.27   1.20         0.09-0.13     0.11       0.38-0.44    0.41
                      14         0.83-0.95   0.89         0.09-0.13     0.11       0.28-0.32    0.30

    2                 20         0.74-0.82   0.77         0.09-0.17     0.12       0.24-0.32    0.28
                      25         0.68-0.73   0.71         0.13-0.16     0.15       0.27-0.29    0.28
                      30         0.63-0.69   0.66         0.13-0.13     0.13       0.24-0.24    0.24
                      35         0.57-0.73   0.65         0.10-0.15     0.13       0.22-0.27    0.25
                      40         0.73-0.82   0.77         0.13-0.16     0.15       0.28-0.30    0.29
                                                                                                        

    1   Spray concentration 0.01% amitraz; application rate 2 600 l/ha; residues determined by 
        "total residue" method.

    TABLE 12.  Amitraz Residues in Oranges from Supervised Trials, China1

                                                                                                        

                                             Residues (mg/kg)
                    Interval                                                                            
    Applications    Days                Peel                      Pulp                Whole fruit
                                                                                                       
                                 Range       Mean         Range         Mean       Range        Mean
                                                                                                        

    1                  0         1.83-1.91   1.88         0.004-0.008   0.006      0.72-0.83    0.77
                      20         0.55-0.62   0.58         0.06-0.11     0.09       0.24-0.29    0.27
                      40         0.26-0.43   0.33         0.05-0.08     0.07       0.13-0.19    0.16

    2                  0         1.47-1.56   1.51         0.06-0.10     0.08       0.53-0.54    0.54
                      20         0.46-0.50   0.48         0.13-0.14     0.13       0.23-0.31    0.26
                      40         0.36-0.38   0.37         0.10-0.14     0.12       0.18-0.20    0.19

    1                  0         1.11-1.13   1.12         0.014-0.016   0.015      0.49-0.54    0.51
                      20         0.57-0.59   0.58         0.08-0.12     0.10       0.27-0.29    0.28
                      40         0.36-0.53   0.46         0.06-0.09     0.08       0.16-0.24    0.20

    2                  0         1.29-1.95   1.61         0.08-0.09     0.09       0.24-0.70    0.50
                      20         0.35-0.36   0.36         0.09~0.13     0.11       0.17-0.19    0.18
                      40         0.25-0.32   0.28         0.07-0.08     0.07       0.12-0.15    0.13
                                                                                                        

    1   Spray concentration 0.01% amitraz; application rate 3 000 l/ha; residues determined by 
        "total residue" method.
    

    (Grower 2) with the corresponding total amitraz-derived residues being
    0.14 and 0.35 mg/kg. Expressed as a percentage of the total 
    amitraz-derived residue, the BTS 24 868 residues ranged from 15.6 to
    18.3 percent. This is outside the range of artefactual conversion of
    the known metabolites to BTS 24 868 and, therefore, indicates that
    approximately 50 percent of the BTS 24 868 residues in peel are "true"
    residues. However, when calculated on a whole fruit basis by combining
    the results from peel and flesh, a maximum value of less than
    0.01 mg/kg BTS 24 868 was obtained (McGibbon, 1984b).

    Pear

         A method has been developed for the analysis of
    2,4-dimethylaniline residues (BTS 24 868) in pears. The recoveries of
    BTS 24 868 from control pears ('Williams','Bon Chretian' and
    'Conference'), fortified at either 0.1 or 0.05 mg/kg, gave an over-all
    mean and standard deviation of 74.3  12.4 percent. Mean BTS 24 868
    residues in control pears fortified with 0.5 mg/kg of either amitraz,
    BTS 27 271 or BTS 27 919 were found to range from 0.006 to 0.018 mg/kg
    (equivalent to 1.5 to 4.3 percent conversion of the parent compounds
    to BTS 24 868). The mean residues of BTS 24 868 in commercially-grown
    pears treated with amitraz under normal field practice ranged from
    0.002 to 0.005 mg/kg, with a minimum detectable level estimated at
    0.001 mg/kg. The level of total amitraz-derived residues in the
    treated pears was found to be in the range 0.10 - 0.20 mg/kg. The
    ratio of BTS 24 868 residues in the treated fruit to the total
    amitraz-derived residue was calculated as 1.2 to 3.9 percent. This is
    within the range of artefactual conversion of coexisting amitraz and
    its metabolites. It follows, therefore, that there is no evidence to
    suggest that specific BTS 24 868 residues exist in the treated pears
    (McGibbon, 1984a).

    Citrus and Processed By-products

         Studies have been conducted on the distribution of amitraz
    residues in citrus and on the effects of processing. In 'Valencia' and
    'Navel' oranges, approximately 80 percent of the residue present at
    harvest was in or on the peel. Residues were more evenly distributed
    in 'Hamlin' oranges, primarily because of their thinner peel. In
    grapefruit, approximately 90 percent of the residue occured in the
    peel. These studies are summarized in Table 13.

         In processing studies dry citrus pulp from processed oranges
    contained residues some four to seven times higher than in fresh
    fruit. Residues in citrus molasses were approximately 50 percent lower
    than those in dry pulp. The remaining fractions contained levels at or
    below those detected in fresh fruit.


        TABLE 13.  Amitraz Residues in Citrus Peel and Flesh from Supervised Trials

                                                                                                                       

                                                                  Amitraz (mg/kg)
    Fruit          Application    Days                                                          
    variety        rate           after          Peel      Whole     Peel      Edible    Flesh          Reference
                   (% a.i.)       application    (%)       fruit               flesh     (%)
                                                                                                                       

    Valencia       0.03              58          27.4      0.31      0.92      0.06       15            Ford, 1981a
    orange

    Navel          0.03             112          29.4      0.08      0.20      0.04       32            Ford, 1981a
    orange

    Navel          0.03 x 2          57          32.2      0.45      1.35      0.05        7            Ford, 1981a
    orange

    Hamlin         0.015            145          20.8      0.057     0.11      0.038      53            Ford, 1980
    orange         0.015 + oil      145          22.2      0.096     0.20      0.067      55
                   0.015            145          20.2      0.045     0.10      0.031      53
                   0.015 + oil      145          20.2      0.051     0.10      0.030      47

    Grapefruit     0.01               1          31.3      0.19      0.62      0.005     1.7            Ford, 1980
                                      8          28.1      0.14      0.44      0.007     3.9
                                     15          25.8      0.11      0.44      0.011     6.7
                                     29          26.0      0.07      0.24      0.010    10.6
                                     43          27.9      0.07      0.27      0.015    12.6

                   0.02               1          37.0      0.37      0.88      0.002     0.4
                                      8          28.9      0.27      0.65      0.008     2.9
                                     15          27.7      0.15      0.53      0.012     5.6
                                     29          30.2      0.16      0.37      0.018     9.4
                                     43          28.8      0.12      0.35      0.015     9.6
                                                                                                                       
    
    FATE OF RESIDUES

    In Plants

         Previous studies (FAO/WHO, 1981b) have shown that
    amitraz degrades rapidly to yield predominantly BTS 27 271
    [N-(2,4-dimethylphenyl)-N'-methylformamidine] and smaller amounts of
    BTS 27 919 (2,4-dimethylformanilide).

    Pears

         Radiolabelled amitraz was applied to commercially grown pears
    (var. 'Conference') at two sites in the United Kingdom (Levington and
    Nottingham). An E.C. formulation was used at a spray concentration of
    0.06 percent a.i. (i.e. identical to that used in the United States).
    Samples of fruit were analysed at maturity 29 days (Levington) and 61
    days (Nottingham) after treatment. At harvest, 48.2 percent of the
    applied radioactivity remained in the fruit, of which BTS 27 271
    (14.0 percent) and BTS 27 919 (5.3 percent) were the main metabolites
    characterized. Amitraz accounted for less than 1 percent, with BTS
    24 868 and BTS 28 037 (N,N'-bis-dimethylphenylformamidine) each
    comprising a further 1.2 percent, although in the case of BTS 24 868
    the amount detected may well be artefactual. Uncharacterized polar
    compounds accounted for 34.8 percent, while the remainder of the
    radioactivity (41.0 percent was fibre-bound (McGibbon & Kelly, 1984b).

    Lemons

         Amitraz was applied to the fruit of lemon trees (cv. 'Four
    Seasons') maintained under glass. An E.C. formulation was used at a
    spray concentration of 0.06 percent a.i. Samples of fruit were
    harvested at maturity 32 days after treatment. At harvest, 89.5
    percent of the applied radioactivity remained in or on the fruit, of
    which 72.5 percent was found in the peel. BTS 27 271 (27.2 percent)
    and BTS 27 919 (9.0 percent) were the main metabolites characterized.
    Unchanged amitraz comprised 12.4 percent, while BTS 28 037 and BTS
    24 868 accounted for 2.2 and 2.8 percent, respectively, of the total
    radioactivity recovered, with the possibility that BTS 24 868 was
    produced as an artefact. Uncharacterized polar compounds accounted for
    25.1 percent while the remainder of the radioactivity (13.2 percent)
    was fibre-bound. (McGibbon & Kelly, 1984a).

         These new data confirm the previous findings that amitraz is
    metabolized within a relatively short time. The major metabolites
    remaining at harvest are BTS 27 271 and BTS 27 919. The presence of
    any significant residues of BTS 24 868 is not indicated by either the
    metabolism studies or the investigations aimed at specific analysis
    for residues of the metabolite. A diagrammatic representation of the
    metabolism of amitraz in plants is given in Figure 1.

    FIGURE 1

    NATIONAL MAXIMUM RESIDUE LIMITS

         The following MRLs from the Netherlands were reported to the
    meeting:

         Pome fruit          0.5 mg/kg

         Strawberries        0.05 mg/kg

         Bell peppers        0.2 mg/kg

         Eggplant            0.2 mg/kg

         Tomatoes            0.2 mg/kg

         Milk                0.05 mg/kg

         Meat                0.05 mg/kg

         Other food          0 (0.05) mg/kg

         Limits include and are expressed as
         N-2,4-dimethylphenyl-N-methylformamidine.

    APPRAISAL

         The meeting examined new residues data on citrus fruit and noted
    that with a 14-day interval between last application and harvest,
    most residue levels were less than the temporary MRL for oranges of
    0.5 mg/kg (for amitraz plus N-2,4-dimethylphenyl-N'-
    methylformamidine), even at the relatively high rates of use in the
    trials in the United States (and approved under an experimental use
    permit). The meeting confirmed its previous estimate.

         Although the maximum residues in some citrus samples were about
    2 mg/kg, it is not known if the high rates used will be recognized as
    good agricultural practice and the meeting, therefore, decided not to
    include these in its evaluation.

    REFERENCES

    Ford, J.J. Persistence of amitraz on Florida-grown Hamelin oranges.
    1980      Report RI 34-017-06 (R 82) submitted by FBC to FAO.
              (Unpublished)

    Ford, J.J. Persistence of the acaricide amitraz on California Citrus -
    1981a     Part II. Report RESID/82/15 (R 133) submitted by FBC to FAO.
              (Unpublished)

    Ford, J.J. Additional residue studies of the acaricide amitraz on
    1981b     Florida-grown citrus. Report RESID/83/43 (R 135) submitted
              by FBC to FAO. (Unpublished)

    Ford, J.J. Residue decline on mature Hamlin oranges treated with three
    1981c     applications of Mitac EC. Report US/R-7 (R 151) submitted by
              FBC to FAO. (Unpublished)

    Goodall, E. & Sommmerville, L. Estimation of combined residues of BTS
    1974      27 419 1974  and BTS 27 271 on Dutch apple and tomato crops.
              Report No. Ax 74028 submitted by Aseptafabriek BV to FAO.
              (Unpublished)

    Greve, P.A. & Hogendoorn, E.A. Residuen van BTS 27 271 in appel en
    1975      tomaat. RIV Report nr. 17/75 Tox-Rob. (Unpublished)

    McGibbon, A.S. Residues of 2,4-dimethylaniline (BTS 24 868) in
    1984a     field-grown pears. Report METAB/84/3 (R 179) submitted by
              FBC to FAO. (Unpublished)

    McGibbon, A.S. Residues of 2,4-dimethylaniline (BTS 24 868) in
    1984b     field-grown oranges. Report METAB/84/5 (R 180) submitted by
              FBC to FAO. (Unpublished)

    McGibbon, A.S. & Kelly, I.D. The metabolism of 14C-amitraz in lemons
    1984a     under glasshouse conditions (an interim report). Report
              METAB/84/6 submitted by FBC to FAO. (Unpublished)

    McGibbon, A.S. & Kelly, I.D. The metabolism of 14C-amitraz in pears
    1984b     (an interim report). Report METAB/84/4 submitted by FBC to
              FAO. (Unpublished)

    Netherlands. Residuproef Asepta Tetranyx of tomaat. Proef nr. 79-167
    1979      submitted by Aseptafabriek BY to FAO. (Unpublished)

    Nissan & Boots. JA-119 (BTS 27 419) Residues analysis - citrus. Report
    1972      (R 162) submitted by Nissan & Boots to FAO. (Unpublished)

    Takano, J. BTS 27 419 residue analysis on citrus and pears and apples
    1974      in Japan. Report 1974 (R 99) submitted by Nissan & Boots to
              FAO. (Unpublished)

    Upjohn & Boots. Residue determinations for U-36,059 (amitraz) and
    1974 -    metabolites in oranges, USA. Report (R 157) submitted by
    1981      Upjohn & Boots to FAO. 1981  (Unpublished)

    Upjohn & Boots. Residue determinations for U-36,059 (amitraz) and
    1981a     metabolites in tangelos, USA. Report (R 158) submitted by
              Upjohn & Boots to FAO. (Unpublished)

    Upjohn & Boots. Residue determinations for U-36,059 (amitraz) and
    1981b     metabolites in tangerines, USA. Report (R 159) submitted by
              Upjohn & Boots to FAO. (Unpublished)

    van Adrichem, J.C.J. & Vogelezang, H.P. Residue-onderzoek amitraz op
    1981      tomaat no toepassing van Asepta Tetranyx d.m.v, puls- of
              swingfog. Rapport 1017/81 submitted by Aseptafabriek BV to
              FAO. (Unpublished)


    See Also:
       Toxicological Abbreviations
       Amitraz (ICSC)
       Amitraz (Pesticide residues in food: 1980 evaluations)
       Amitraz (Pesticide residues in food: 1983 evaluations)
       Amitraz (Pesticide residues in food: 1984 evaluations)
       Amitraz (JMPR Evaluations 1998 Part II Toxicological)