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    THIABENDAZOLE      JMPR 1975

    Explanation

         Thiabendazole was evaluated by the Joint Meeting in 1970 (FAO/WHO
    1971), 1971 (FAO/WHO 1972) and 1972 (FAO/WHO 1973). Tolerances were
    proposed for apples, pears, bananas and citrus fruits. Since that time
    a considerable amount of information has been obtained on extended
    uses for tuber treatment of potatoes and sweet potatoes. Thiabendazole
    is used on seed potatoes during storage before planting as well as on
    potatoes intended for human or animal consumption to prevent rot
    during storage. Some additional data were obtained on residues in milk
    of dairy cattle after continuously administering feed containing 10-30
    mg thiabendazole/kg. This monograph addendum is an evaluation of the
    new data.

    USE PATTERN

         Registered or considered uses of thiabendazole additional to
    those mentioned in previous evaluations are summarized in Table 1.

    RESIDUES RESULTING FROM SUPERVISED TRIALS

    Potatoes

         Extensive data resulting from several trials carried out in
    Denmark, the Netherlands and the United States have been examined,
    together with limited data from Ireland and the United Kingdom. They
    are summarized in Table 2.

    FATE OF RESIDUES

    In animals

         Lactating dairy cattle were fed continuously during 3-4 weeks
    with food containing 10, 20 and 30 mg/kg thiabendazole. No residues
    were found (limit of determination 0.1 mg/kg) in the milk of cattle
    fed 10 and 20 mg/kg. One of 12 milk samples taken from cows fed 30
    mg/kg showed an apparent residue of thiabendazole plus its main
    metabolites slightly abate the limit of determination (0.1 mg/kg); no
    residue was found in the other samples (Warf Inst. Inc., 1974).

    In storage and processing

         During storage for 3-4 months the initial thiabendazole residue
    decreased only slightly. Washing the potatoes before analysis, as in
    household practice, resulted in a decrease of 43-73% in the 1974-75
    Danish residue trials and 40-77% in the 1973/1974 Netherlands trials
    (see Table 2).


    
    TABLE 1.  Use patterns of thiabendazole in potatoes, sweet potatoes and sugar beets
                                                                                                                                               
                                                                                   Application rate
      Country          Crop          Use                 Formulation      formulation          active ingredient       Type of treatment
                                                                                                                                               

    United States     seed-potato   Only against         Suspension       42 fl. oz/100        ca 5g a.i./1000         Spraying on conveyer
    of America        "edible"      fusarium rot         42-45% a.i.      gallon               kg potatoes             band, sometimes followed
                      potatoes                                            1 gallon/metric                              by dipping in the same
                                                                          tonne potatoes                               concentration

                                                         wp 60%           2 pounds/100         ca 5g a.i./1000                 "
                                                                          gallon               kg potatoes
                                                                          1 gallon/metric
                                                                          tonne potatoes

    Denmark           seed-         Rot caused by        suspension       4.7 l/100 litre      ca 42g a.i./            spraying on
    Federal           potatoes      black scurf          42-45% a.i.      2 litre/metric       1000 kg                 conveyer band
    Republic of                     Rhizoctonia                           tonne                potatoes                or swing-fog
    Germany                         solani                                potatoes                                     treatment of
                                    skin spot                                                                          storage bins
    Netherlands                     Oospora postulans
                                    silver scurf         wp 60%           3.5 kg/100 l         ca 42 gr a.i./                "
                                    Helminthosporium                      2 litre              1000 kg
                                    solani                                suspension/metric
                                                                          tonne potatoes

                                    gangrene             smoke
                                    Phoma exigua         tablets 12%                           ca 40g a.i./
                                                                                               1000 kg

    United States     sweet-        Black rot            suspension       110-130 fl. oz/                              root dip
    of America        potato        scurf                                 42-45% a.i.          100 gallon
                      (seed roots)  foot rot

                      sugar beet    Cercospora leaf      suspension       6-12 fl. oz/         0.3-0.6 kg/ha           spraying of
                                    spot                                  42-45% a.i.          acre                    aerial parts

                                                         wp 60%           5-10 oz/acre         0.3-0.6 kg/ha              "     "
                                                                                                                                               

    TABLE 2.  Thiabendazole residues in potatoes resulting from supervised trials

                                                                                                                                               

                                                                                     Residues, mg/kg
               Country                           Application
               (references                 g a.i.               Storage              Unwashed                            Washed
               in                          metric               period,   Whole                    edible      Whole                 edible
     Crop      parenthesis)    Year   No.  tonne   Formulation  months    potato     peel          portion     potato    peel        portion
                                                                                                                                               

    Potatoes   Denmark         1974/  1     40     wp 60%         0         2                                  2.8       10.3        0.07*
    (edible)   (Holm,          1975                Mist spray
    Bintje     1975)                                              1         5.9       36.8         0.05        1.6       9.5         0.02
                                                                  2         5.9       33.8         0.06
                                      1     40     smoke tablet   0      10.8, 10.0  46.0, 49.2   0.50, 0.15
                                                   12%            1      9.8, 8.9    50.5, 42.3   0.07, 0.22   4.0, 4.7  21.7, 25.8  0.04, 0.07
                                                                  2      7.9, 6.4    43,1, 35.4   0.21, 0.08
                                      1     40     Pulsfog        0      10.6, 6.7   56.1, 33.9   0.09, 0.14
                                                   form           1      6.9, 5.7    37.3, 31.0   0.19, 0.10   3.9, 0.6  18.9, 8.7   0.08, 0.05
                                                                  2      10.2, 5.1   57.5, 27.2   0.16,0.07
    Kennebeck                  1974/  1            wp 60%         0         4.6       25.2         1.9
                               1975                Mist spray
                                      1                           0         5.0       43.9         0.32
    Desire                            1                           0         2.7       18.2         4.3
               Ireland         1974   1     42     wp 60%                   9.22
               (Logan, 1974;                       Mist spray            (8.45-13.3)
               Merck, Sharp
               and Dohme,
               1974 b)
               United Kingdom  1972/  1    ca 45   dust 1%                  2.3**
               (Tisdale and    1973
               Lord, 1973)            1    ca 225  dust 5%                  4.8**

    TABLE 2.  (Cont'd.)
                                                                                                                                               
                                                                                     Residues, mg/kg
               Country                           Application
               (references                g a.i.              Storage  Whole                         Unwashed potatoes
               in                         metric              period,  washed      whole                    edible       Ratio:  Notes
     Crop      parenthesis)   Year   No.  tonne  Formulation  months   potato      potato       peel        part         peel:      
                                                                                                                         edible
                                                                                                                         part  
                                                                                                                                               

    Potatoes   Netherlands    1973/  1   25     suspension    0                    2.71         41.8        0.27         1:16
               (Merck, Sharp  1974              42-45.1%
               and Dohme,                                     6        0.74        3.18         14.9        ***          1:4.8
               1974c, 1975)              25     wp 30-40%     0                    2.07         31.2        0.25         1:16
                                                acid form
                                     1   25     Wäcker form   0                    1.87         25.2        0.41         1:16
                                                15%
                                     2   25+25  suspension    0        1.75        3.51         75.         ***          1:16
                                                42-45%        4.5      0.54        0.93         5.14        0.04         1:4.8   Average whole
                                                                     (0.23-0.78)  (0.89-1.01)  (4.75-5.60)  (0.02-0.10)          pile and range
                                                              6        1.02        2.01         9.1         0.53         1:4.8   Top layer of
                                                                                                                                 pile
                                     2   25+25  wp 30-40%     0        2.09        3.51         5.10        0.54         1:16    Average whole
                                                acid form            (0.81-1.29)  (1.43-2.24)  (6.45-10.8)  (0.33-0.57)  1:4.8   pile and range
                                                              6        0.90        2.22         10.9        0.41         1:4.8   Top layer of
                                                                                                                                 pile
                                     2   25+25  Wäcker form   0        0.76        2.21         22.0        ***          1:16
                                                15%
                                                              4.5      1.44        2.86         14.9        0.37         1.4.8   Average whole
                                                                     (0.79-1.70)  (1.41-3.78)  (7.5-21.6)   (0.07-0.69)  1.4.8   pile and range
                                                              6        2.05        3.00         16.0        0.29         1.4.8   Top layer only
                                     3   3×25   Suspension    2.5      1.62        4.16         14.5        ***          1.4.8
                                     3   3×25   wp 30-40%     2.5      1.90        3.58         19.2        0.32         1.4.8
                                                acid form

                                     3   3×25   Wäcker form   2.5      2.84        5.38         26.0        1.09         1.4.8
                                                15%
                              1974/  1   10     suspension             0.13
                              1975              45%
                                                Pulsfog

    TABLE 2.  (Cont'd.)
                                                                                                                                               
                                                                                     Residues, mg/kg
               Country                           Application
               (references                g a.i.              Storage  Whole                         Unwashed potatoes
               in                         metric              period,  washed      whole                    edible       Ratio:  Notes
     Crop      parenthesis)   Year   No.  tonne  Formulation  months   potato      potato       peel        part         peel:      
                                                                                                                         edible
                                                                                                                         part  
                                                                                                                                               
    Potatoes   Netherlands    1974/  1   10     suspension             0.39
               (Merck, Sharp  1975              45%
               and Dohme,                       Mist spray
               1974c, 1975)              10     Dust, thermal          0.32
                                                dusting
                                                application

                                                                                  Prior to treatment

                                                                Storage                                           Unwashed
                                                                period
                                                                w=weeks                                          washed prior
                                                                m=months         Unwashed          Washed        to analysis
                                                                                                                              
    Potatoes   United States  1972   1   5.5    wp 60%           1 w             1.16-1.30        0.01-0.02
               (Merck, Sharp             10.5   wp 60%           1 w             2.16-2.30
               and Dohme,
               1974a)
    Russet                               5.5    wp 60%          11 m             0.97-1.01
    Burbank                              10.9   wp 60%          11 m             1.13-1.15
                                         2.7    wp 60%          11 m             1.48-2.53        0.97-1.02
                                         5.5    wp 60%          11 m             1.63-2.87        1.41-1.44
                                         10.9   wp 60%          11 m             1.85-3.00        0.16-0.17
                                         5.5    wp 60%          1-1/2 w          1.62-1.65        0.75-0.77
                                                                24-29 w                           1.40-1.66
                                         10.9   wp 60%          1-1/2 w          2.94-3.06        1.36-1.37
                                                                24-29 w                           3.37-3.41

    TABLE 2.  (Cont'd.)
                                                                                                                                               
                                                                                     Residues, mg/kg
               Country                           Application
               (references                g a.i.              Storage  Whole                         Unwashed potatoes
               in                         metric              period,  washed      whole                    edible       Ratio:  Notes
     Crop      parenthesis)   Year   No.  tonne  Formulation  months   potato      potato       peel        part         peel:      
                                                                                                                         edible
                                                                                                                         part  
                                                                                                                                               
    Monona and
    Russet                    1973   1   5.5    suspension      1-1/2 w          0.45-0.56                       0.36-0.46
    Burbank                                     40% wp
                                         10.9       "           1-1/2 w          0.91-1.54                       0.40-0.88
                                         5.5        "            5 w             0.44-0.52                       0.40-0.52
                                         10.9       "            5 w             0.90-1.18                       0.45-1.07
                                         5.5        "            11 w            0.49-0.52        0.40-0.72
                                         10.9       "            11 w            0.90-1.18                       0.45-1.16
                                         5.5        "            22 w            0.69-0.40                       0.48-0.52
                                         10.9       "            22 w            0.95-1.66                       0.6 -0.88
                                         5.5        "            30 w            0.44-0.60                       0.44-0.48
                                         10.9       "            30 w            0.83-1.22                       0.58-1.00
                                                                                                                                               

    *    Samples erroneously washed before analysis.
    **   Dust removed by brushing before analysis.
    ***  Sample analysis unreliable.
    

         The remaining residue occurred mainly in the skin. It was shown
    in an experiment carried out in Idaho, United States of America, in
    1974 (Merck, Sharp and Dohme, 1974d) that further processing to French
    fries, especially peeling, removed most of the remaining residue
    (Table 3).

        TABLE 3.  Effect of processing on thiabendazole residues in potatoes
                                                                                       

    Thiabendazole residues, mg/kg
    Potatoes and potato products
                                               French                Waste
                        After                  fries                 Trim      Caustic
                        caustic     After      not                   table     waste
    Unwashed   Washed   treatment   peeling    fried      In peel    waste     liquid
                                                                                       

    1.44       1.00     0.23        0.02       0.01       2.50       0.16      0.02
    3.41       2.10     0.40        0.03       0.01       5.28       0.16      0.12
                                                                                       
    
    NATIONAL TOLERANCES REPORTED TO THE MEETING

         National tolerances established or changed since the 1972 Joint
    Meeting (other than tolerances on apples, pears, bananas and citrus
    fruits) are listed in Table 4.

    TABLE 4.  National tolerances reported to the Meeting
                                                                             
                                                                    Tolerance,
    Country          Commodity                                      mg/kg
                                                                             

    Australia        meat                                              0.2
                     milk                                              0.05

    Israel           celery                                            5
                     strawberries                                      3

    Netherlands      tomatoes                                          0.1

    United           potatoes (from post harvest applications)         3
    States of        milk, fat, meat and meat by-products of
    America          cattle, goats, hogs, horses and sheep             0.1*

                     sugar beet (excluding tops)                       0.25

                     sugar beet tops                                  10
                     dried or dehydrated sugar-beet pulp               3.5
                                                                             
    *  Combined residue of thiabendazole and 5-hydroxythiabendazole
       ref: USA Fed. Reg. 1975.

    APPRAISAL

         Extensive data became available from the United States, Denmark
    and the Netherlands together with some from Ireland and the United
    Kingdom on the use of thiabendazole on potato tubers and residues
    resulting therefrom.

         Some additional data on the residues in milk after feeding cows
    with feed containing 10-30 mg/kg of thiabendazole were evaluated. No
    residues were found (limit of determination 0.1 mg/kg) in milk of
    dairy cattle fed continuously for 3-4 weeks on feed containing these
    residue levels.

         Data from supervised trials on the residues in seed potatoes and
    edible potatoes were evaluated. Since seed potatoes may be used to
    some extent for human consumption or as animal feed the establishment
    of a maximum residue level is desirable.

         The dosage rates applied in the United States are considerably
    lower than those applied in some European countries. In the latter the
    treatment is used to control a larger number of tuber diseases, some
    of which require higher dosage rates.

         The amount of the initial residue after treatment depends largely
    on the dosage rates applied, the type of formulation, the method of
    application and the amount of adhering soil. Since the residue remains
    mainly on the skin however, household washing and especially peeling,
    decreases the residues remaining after storage to very low levels.
    Industrial processing involving washing and/or brushing reduced
    residues in the tubers to levels at or about the limit of
    determination.

         National tolerances have been established in some countries for
    thiabendazole on or in potatoes and in products of animal origin.

         Since maximum residue limits for pesticides are established in
    various countries on either unwashed or washed potatoes, and since
    washed potatoes are an item of international trade, it is desirable to
    establish limits on both unwashed and washed potatoes.

    RECOMMENDATIONS

         In the light of the new data and data previously available, the
    following additional maximum residue limits are recommended. They
    refer to thiabendazole + 5-hydroxythiabendazole, expressed as
    thiabendazole.

    MAXIMUM RESIDUE LIMITS

                                                           

                                                 Limit,
    Commodity                                    mg/kg
                                                           

    Potatoes (unwashed)                          10

    Potatoes (washed)                            3

    Milk, meat and meat products of
    cattle, goats, horses, pigs and
    sheep                                         0.1*
                                                           

    * At or about the limit of determination of combined residue of
    thiabendazole and 5-hydroxythiabendazole.


    FURTHER WORK OR INFORMATION

    DESIRABLE

         1.   Data on current use patterns to various countries,
    especially on pre-harvest uses, and on resulting residue levels
    including those on grain crops, strawberries and tomatoes.


    REFERENCES

    Holm, F. (1975) Rapport over restkoncentrationer af thiabendazole i
    Kartofler. rep, Bioteknisk Institut, Kolding Danmark for Merck Sharpe
    & Dohme.

    Logan, C. (1974) Potato tuber disinfection by Thiabendazole Mist
    Application. Agriculture in Northern Ireland, 48:439-440.

    Merck, Sharp and Dohme. (1974a) Residue data in the petition for
    registration in the USA of the pesticide chemical thiabendazole on raw
    agricultural chemicals; White potato, 28 June 1974.

    Merck, Sharp and Dohme. (1974b) Residue analysis by Merck, Sharp &
    Dohme Ltd, Hodderson, England on samples of treated potatoes from 1974
    trials by Dr Logan. Dept. of Agr. Belfast, N. Ireland. Unpublished
    report, Merck, Sharp & Dohme.

    Merck, Sharp and Dohme. (1974c) Residue data on potatoes after
    treatment with thiabendazole; data generated from 1973-1974 trials in
    Holland with analysis made by Merck, Sharp & Dohme. Unpublished report
    of Merck, Sharp & Dohme.

    Merck, Sharp and Dohme. (1974d) Commercial processing of thiabendazole
    treated Russett Burbank potatoes into French fries; 1974 Idaho
    experiment. Data in the Petition for registration in the USA of the
    pesticide chemical thiabendazole on raw agricultural commodities.
    White potato, 28 June 1974.

    Merck, Sharp and Dohme. (1975) Residue limits (from the Netherlands)
    on potatoes treated with various methods of application of
    thiabendazole and washed before analysis. Unpublished report Merck,
    Sharp & Dohme.

    Tisdale, M. J. and Lord, K. A. (1973) Uptake and distribution of
    thiabendazole by seed potatoes. Pesticide Science, 4:121-130.

    USA Fed. Reg. (1975) Fed. Register Vol. 40 No. 117, Tuesday 17 June
    1975. Tolerances for thiabendazole in or on raw agricultural
    commodities.

    Warf Inst. Inc. (1974) Thiabendazole studies on residues in milk of
    dairy cattle fed thiabendazole continuously in feed. Report Warf Inst.
    Inc. for Merck, Sharp & Dohme in the Petition for registration in the
    USA of the pesticide chemical thiabendazole on raw agricultural
    commodities; white potato, 28 June 1974.
    


    See Also:
       Toxicological Abbreviations
       Thiabendazole (WHO Food Additives Series 39)
       Thiabendazole (AGP:1970/M/12/1)
       Thiabendazole (WHO Pesticide Residues Series 1)
       Thiabendazole (WHO Pesticide Residues Series 2)
       Thiabendazole (Pesticide residues in food: 1977 evaluations)
       Thiabendazole (Pesticide residues in food: 1979 evaluations)
       Thiabendazole (Pesticide residues in food: 1981 evaluations)