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    PESTICIDE RESIDUES IN FOOD - 1983


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    EVALUATIONS 1983





    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
    Geneva, 5 - 14 December 1983

    Food and Agriculture Organization of the United Nations
    Rome 1985

    TRIADIMEFON

    TOXICOLOGY

    Explanation

         Triadimefon was evaluated by the 1979 Joint Meeting (FAO/WHO
    1980)1 and as no acceptable daily intake (ADI) was allocated at that
    Meeting, guideline levels were proposed. At the 1982 Joint Meeting, a
    temporary ADI was allocated, and guideline levels were changed to
    temporary maximum residue limits.

         Further studies were desired on livestock animals for
    establishing a dose-response relationship between feed contents and
    residues in animal tissues, including realistic feeding levels.
    Information was also desired on residue levels in coffee and hope and
    in pineapples after appropriate postharvest treatments.

         New residue data has been received on triadimefon and its main
    metabolite, triadimenol, in fruit, coffee, grains and pineapple
    (postharvest). Data have also been provided from feeding experiments,
    where cattle and poultry were fed with triadimefon-triadimenol
    mixtures. In addition, data have become available from studies on
    metabolism in plants and behaviour of the compounds in water and soil.
    These data are evaluated in this monograph addendum.

    EVALUATION FOR ACCEPTABLE DAILY INTAKE

    TOXICOLOGICAL STUDIES

    Special Studies on Teratogenicity

         Emulsified triadimefon (93.2 percent pure) was administered by
    gavage daily to pregnant CD-SD rats on days 6 to 15 of gestation at 0,
    10, 30 and 90 mg/kg. Animals were sacrificed on gestation day 20 and
    foetuses were examined for gross, soft tissue and skeletal anomalies.
    Maternal toxicity, indicated by decreased body weight gains, occurred
    at 90 mg/kg. Implantation rates, number of viable foetuses, resorption
    rates, litter size, sex ratio and average foetal weight were not
    influenced by treatment. Anomalies of the urogenital system, namely
    hydronephrosis and distension of the urinary bladder, were noted at
    the 30 and 90 mg/kg levels, but the increases were without statistical
    significance. A significant number of extra ribs occurred at 90 mg/kg
    but other skeletal abnormalities, incompletely ossified and wavy ribs,
    were not statistically significant. Thus, the no-effect level from
    this study corresponded to 30 mg/kg (Unger et al. 1982).


              

    1  See Annex 2 for FAO and WHO documentation.

         Groups of 12 Himalayan rabbits received daily doses by gastric
    tube of 0, 10, 30 and 100 mg/kg of emulsified triadimefon from days 6
    to 18 of gestation. The dams were sacrificed at day 29 and foetuses,
    delivered by Caesarean section, were examined for gross, soft tissue
    and skeletal abnormalities.

         Only dams treated at 100 mg/kg exhibited symptoms of maternal
    toxicity, namely reduced food intake, diarrhoea or reduced stool
    volume and swelling or inflammation of the external vagina, with
    weight loss during treatment. A slight reduction in maternal weight
    gain during treatment at 30 mg/kg was not statistically significant.

         At 100 mg/kg, the rate of intrauterine foetal loss and the
    male/female sex ratio increased; the latter was possibly associated
    with the reduced total number of foetuses. Mean foetal and placental
    weights were unaffected and there was no increase in the incidences of
    skeletal deformities, malformation or growth stunting of foetuses. The
    results of this study suggest 30 mg/kg as the no-effect level for
    reproductive toxicity in the Himalayan rabbit (Roetz 1982).

    Special Studies on Skin Sensitization

         Triadimefon (97 percent pure) did not exhibit dermal sensitizing
    properties in guinea pigs when injected intracutaneously and by dermal
    patch testing (Iyatomi 1981).

    Special Studies on Neurotoxicity

         In male mice, strain Bor:CFI(SPF), triadimefon did not prolong
    hexobarbital anaesthesia; exhibit anticonvulsant, cataleptic or
    analgesic effects; inhibit traction capability, or orientational or
    spontaneous mobility at 0, 0.3 or 3.0 mg/kg. At the same doses, male
    rats exhibited no cataleptic effects and neuromuscular transmission,
    as indicated by electrophysiological techniques, was not significantly
    affected (Polacek 1983).

    Special Studies on Induction of Liver Enzymes

         In vitro, technical triadimefon was a modest inhibitor of both
    rat and mouse liver microsomal O-de-ethylation of 7-ethoxycoumarin,
    aldrin epoxidation and biphenyl hydroxylation. It caused a spectral
    shift characteristic of substrate binding with cytochrome-P450.

         When administered daily for seven days to male and female rats,
    triadimefon induced hepatic mono-oxygenase activity (aldrin
    epoxidation, 7-ethoxycoumarin O-de-ethylation) at 30 mg/kg in males
    and 10 mg/kg in females. However, triadimefon did not induce 2- or 
    4-hydroxylation of biphenyl significantly.

         In mice, daily doses of triadimefon induced aldrin epoxidation in
    both males and females at 50 mg/kg and 7-ethoxycoumarin O-de-ethylase
    caused such induction at 50 mg/kg in males and at 100 mg/kg in females
    (Schmidt 1983).

    COMMENTS

         Studies in rats and rabbits confirmed previous findings that
    triadimefon has little or no teratogenic potential. The signs of acute
    poisoning indicate central nervous system toxicity, but investigations
    on the mechanism of this were inconclusive. In vitro, triadimefon
    inhibited hepatic microsomal de-ethylation of 7-ethoxycoumarin, aldrin
    epoxidation and biphenyl hydroxylation, and was bound to cytochrome 
    P-450. In rats and mice fed with triadimefon, induction of 
    7-ethoxycoumarin de-ethylation and aldrin epoxidation, but not of
    biphenyl hydroxylation or cytochrome P-450 level, occurred. These
    results confirm previous findings but do not explain either the
    treatment-related increase in liver weights or the hyperplastic liver
    nodules previously reported in rats and mice. The Meeting agreed to
    extend the temporary ADI until 1985.

    TOXICOLOGICAL EVALUATION

    Level Causing no Toxicological Effect

         Mouse:    300 ppm in the diet, equivalent to 40 mg/kg b.w.
         Rat:      50 ppm in the diet, equivalent to 2.5 mg/kg b.w.
         Dog:      230 ppm in the diet, equivalent to 8.25 mg/kg b.w.

    Estimate of Temporary Acceptable Daily Intake for Man

         0-0.01 mg/kg b.w.

    FURTHER WORK OR INFORMATION

    Required (by 1985)

         Clarification of the toxicological significance of hepatic
    toxicity in rats and mice and of the hyperplastic liver nodules
    observed in chronic mouse feeding studies.

    Desirable

         Observations in humans.

    REFERENCES - TOXICOLOGY

    Iyatomi, A. Report of acute toxicity. Tokoyo report sheet No. 25
    1981      submitted to WHO by Bayer AG. (Unpublished)

    Polacek, I. Safety pharmacology study with MEB 6447 on oral
    1983      administration. Toxicological Institute, Regensburg, Report
              No. R 2428 submitted to WHO by Bayer AG. (Unpublished).

    Roetz, R. MEB 6447. Evaluation for embryotoxic effects on rabbits
    1982      after oral administration. Bayer AG, Institute for
              Toxicology, Report No. 10831 submitted to WHO by Bayer AG.
              (Unpublished)

    Schmidt, U. Interaction of triadimefon with liver microsomes, studies
    1983      on rat and mouse in vivo and in vitro. Bayer Ag,
              Institute for Toxicology, Report No. 11812 submitted to WHO
              by Bayer AG. (Unpublished)

    Unger, T.M., Van Goethem, D. & Shellenberger, T.E. A teratological
    1982      evaluation of Bayleton in mated female rats. Midwest
              Research Institute, Report No. 324 to Mobay Chemical
              Corporation Agricultural Chemical Division submitted to WHO
              by Bayer AG. (Unpublished)

    RESIDUES

    RESIDUES IN FOOD AND THEIR EVALUATION

    USE PATTERN

         Information on good agricultural practice has been provided to
    the Meeting and is summarized in Table 1.

    RESIDUES RESULTING FROM SUPERVISED TRIALS

         Additional residue data were available from five countries, which
    were submitted by the originating manufacturer (Bayer AG) and from two
    others through government institutes. Preharvest trials were performed
    on 14 commodities and postharvest trials on one commodity. Results
    from the field trials are summarized in Table 2. Results are presented
    separately for triadimefon and its main metabolite triadimenol.

    Pome Fruits

         Apples were treated 12 times with triadimefon and no residues
    were found two weeks after last treatment. Pears which received the
    same application contained residues up to a total of 0.42 mg/kg.

        Table 1.  Use Patterns of Triadimefon

                                                                                              

                        g a.i./ha             No. of treatments       Safety interval
                                                                      in days
                                                                                              

    Europe (excl. Mediterranean region)

    Cereals             125 - 250                  1 - 3                 28 - 42
    Pome fruit          30 - 125                   3 - 12                7 - 35
    Grapes              50                         4 - 8                 14 - 35
    Cucumbers           30                         4 - 8                 3 - 14
                        (field-grown)
                        15 - 30                    4 - 10                3 - 14
                        (under glass)
    Sugar beet          125                        2 - 3                 35
    Hops                125 - 175                  2 - 4                 14

    Europe (Mediterranean region)

    Cereals             125 - 250                  1 - 2                 15 - 30
    Pome fruit          40 - 75                    4 - 12                7 - 15
    Grapes              50 - 75                    4 - 10                15 - 28
                        100 - 200 (Dust)           4 - 8                 15 - 28
    Cucurbits           25 - 100                   4 - 10                7 - 15
    Tomatoes            50 - 150                   4 - 8                 3 - 7

    Middle East

    Cereals             125 - 250                  1 - 2                 31 - 35
    Pome fruit          40 - 75                    4 - 12                14
    Peaches             50 - 150                   4 - 6                 7
    Grapes              50 - 75                    4 - 10                14 - 28
    Mango               100 - 200                  4 - 5                 28
    Cucurbits           25 - 100                   4 - 10                3 - 7
    Tomatoes            50 - 150                   4 - 8                 3 - 7
    Tobacco             40 - 75                    4 - 6                 7

    Far East

    Pome fruit          60 - 100                   3 - 6                 5 - 10
    Grapes              25                         2 - 3                 6
    Mango               50                         2 - 4                 6
    Cucurbits           25 - 35                    3                     3 - 6
                                                                                              

    Table 1. (continued)

                                                                                              

                        g a.i./ha             No. of treatments       Safety interval
                                                                      in days
                                                                                              

    Africa

    Cereals             125 - 250             1 - 2                   21 - 35
    Pome fruit          38                    4 - 12                  7
    Grapes              63                    4 - 10                  7
    Beans               125                   3 - 6                   14
    Coffee              100 - 250             2 - 4                   7
                        (protective)
                        250 - 500             2                       7
                        (eradicative)
    Vegetables          63                    7                       14

    Australia, New Zealand

    Cereals             125 - 250             1 - 2                   28
    Pome fruit          55 - 75               3 - 8                   14 - 49
    Grapes              13 - 38               4 - 10                  14 - 28
    Cucurbits           25 - 50               4 - 10                  3 - 7

    South America

    Cereals             125 - 250             1 - 2                   21 - 35
    Pome fruit          40 - 75               4 - 12                  14
    Grapes              50 - 75               4 - 10                  14
    Cucurbits           25 - 100              4 - 15                  7
    Coffee              125 - 250             2 - 4
                        (protective)
                        250 - 500             2
                        (curative)

    North America

    Grapes              70 - 210              3                       14
    Pome fruit          140 - 280             3                       -
                                                                                              
    
        Table 2.  Residues of Triadimefon and Triadimenol from Supervised Trials on Fruit and Vegetables

                                                                                                                                             

    Crop            Dose a.i.           No.                                       Residue (mg/kg)                                Country
                    g/ha                Appl.     Day              Triadimefon                      Triadimenol
                                                           range               average       range             average
                                                                                                                                             

    Pome fruit
    Apple           Bayleton spezial    12        7        0.03                0.03 (2)      n.d. - 0.06       < 0.06 (2)        FRG
                    5 WP                          10       n.d. - 0.05         < 0.03 (2)    n.d. - 0.09       < 0.06 (2)
                    37,5                          14       n.d.                n.d. (2)      n.d. -<0.06       < 0.06 (2)
                                                  21       n.d.                n.d. (2)      < 0.06 - 0.08     < 0.06 (2)

    Pears           Bayleton spezial    12        7        0.34                0.34 (1)      0.07              0.07 (1)          FRG
                    5 WP                          10       0.34                0.34 (1)      0.08              0.08 (1)[
                    37,5                          14       0.35                0.35 (1)      0.07              0.07 (1)
                                                  21       0.21                0.21 (1)      < 0.06            < 0.06 (1)


    Wine Grapes     Bayleton spezial    8         14       0.026- 0.13         0.08 (2)      0.038 - 1.6       0.82 (2)          FRG
                    5 WP                          28       <0.02 - 0.083       0.05 (2)      < 0.05 - 1.6      0.81 (2)
                    25 - 50                       35       <0.02 - 0.047       0.03 (2)      < 0.05 - 1.2      0.61 (2)

    Must                                          35       <0.02 - n.d.        < 0.02 (2)    < 0.05 - 0.20     0.11 (2)          FRG

    Wine                                          55/62    <0.02 - n.d.        < 0.02 (2)    n.d. - 0.11       0.05 (2)

                    Bayleton 5 WG       8-9       14       n.d. - 0.10         0.05 (4)      n.d. - 2.7        0.77 (4)
                    25 - 50                       28       n.d. - 0.09         0.03 (4)      n.d. - 2.8        0.77 (4)
                                                  35       n.d - 0.08          0.03 (4)      n.d. - 3.1        0.84 (4)

    Must                                          35       <0.02 - n.d.        < 0.02 (4)    n.d. - 0.39       0.1 (4)

    Wine                                          <0.02 - n.d.                 < 0.02 (4)    n.d. - 0.27       0.07 (4)

    Table Grapes    Bayleton 25 WP      1-2       102 -    n.d.                n.d. (4)      n.d. - 0.05       < 0.05 (4)        Chile
                    25 - 60                       110
                                                                                                                                             

    Table 2. (Continued)

                                                                                                                                             

    Crop            Dose a.i.           No.                                      Residue (mg/kg)                                 Country
                    g/ha                Appl.     Day              Triadimefon                      Triadimenol
                                                           range               average       range             average
                                                                                                                                             

    Black currant   Bayleton 5 WP       3-4       2        0.05-0.06           0.06(2)       0.13-0.13         0.13(2)           Sweden
                    40 g

                                        3         37-46    <0.01-0.01          <0.01(5)      <0.01-0.03        0.02(5)
                                        4         37-46    <0.01-<0.01         <0.01(5)      0.01-0.03         0.02(5)
                    Bayleton 5 WP       4         0        0.23-0.43           0.33          0.18-0.21         0.19              Denmark
                    37.5g               4         15       0.06-0.07           0.06          0.16-0.16         0.16

    Strawberries    Bayleton 5 WP       3         15       <0.01-<0.01         <0.01(2)      <0.01-0.01        <0.02(2)          Denmark
                    50 g
                                        3         18       <0.01-<0.01         0.01(2)       0.01-0.01         0.01(2)

                                        3         25       <0.01-<0.01         <0.01(2)      <0.01- 0.01       <0.01(2)

    Cucumber        Bayleton F5                   1        0.02-0.02           0.02(2)       <0.02-<0.02       <0.02(2)          Denmark

                                        1         3        <0.01-0.01          <0.01(2)      <0.02-<0.02       <0.02(2)

    Sugar Beet      Bayleton 25 WP      3                                                                                        FRG
                    125 g/ha

    Roots                                         35       n.d.                n.d. (2)      n.d.              n.d. (2)

    Leaves                                        35       n.d.                n.d. (2)      n.d. - 0.07       < 0.06 (2)

    Fodder Beet     Bayleton 25 WP      3                                                                                        FRG
                    125 g/ha            J

    Roots                                         35       n.d.                n.d. (3)      n.d.              n.d. (3)

    Leaves                              35        n.d.     n.d. (3)            n.d. - < 0.06 < 0.06 (3)

                                                                                                                                             

    Table 2. (Continued)

                                                                                                                                             

    Crop            Dose a.i.           No.                                       Residue (mg/kg)                                Country
                    g/ha                Appl.     Day              Triadimefon                      Triadimenol
                                                           range               average       range             average
                                                                                                                                             

    Coffee          Bayleton 25 WP      1-2                                                                                      El
                    250 - 500 g/ha                                                                                               Salvador

    Beans                                         24-75    n.d.                n.d. (9)      n.d               n.d. (9)          India

    Pineapple       Bayleton 250 EC     1                                                                                        Ivory
    Fruit           25 - 100 ml/1                 0        n.d. - 0.07         < 0.05 (2)    n.d. - n.d.       < 0.06 (2)        Coast
                    Dipping

    Peel                                          0        0.33 - 1.2          0.72 (2)      0.53 - 1.2        0.87 (2)


    Total                                         0        0.04 - 0.25         0.15 (2)      0.06 - 0.20       0.13 (2)
                                                                                                                                             
    
    Grapes, Must and Wine

         Wine grapes were treated eight or nine times on various
    experimental sites in the Federal Republic of Germany. No residues of
    triadimefon were found but residues of triadimenol as much as 0.2
    mg/kg occurred 35 days after the last treatment. Must and wine
    produced from grapes contained no residues of triadimefon, whereas
    must and wine contained triadimenol up to 0.39 and 0.27 mg/kg,
    respectively.

         Results from supervised trials in Chile on table grapes showed no
    residues or residues at about the limits of determination.

    Berries

         Black currants treated three or four times contained total
    residues of up to 0.22 mg/kg 15 days after last treatment but no
    residues or very low ones 37 days after the last treatment.
    Strawberries treated three times contained residues at or about limits
    of determination two weeks after last treatment.

    Beets

         After treatment with three applications on sugarbeets and fodder
    beets, beets were harvested after 35 days. No residues were found of
    the parent compound and triadimenol was present only at the limit of
    determination.

    Pineapples

         Experiments were performed with postharvest dippings at
    concentrations 25 and 100 mg a.i./l, and samples were analysed the
    same day. Residues were in the same order of magnitude as residues
    evaluated at the 1979 J.M.P.R.

    Coffee

         Supervised trials on coffee were carried on in El Salvador and
    India. No residues of triadimefon or triadimenol were found in beans
    harvested 24-75 days after treatment.

    Cereals

         Several trials have been carried on with applications of
    triadimefon on cereal crops. Results are presented in Table 3. In all
    trials, plants were sprayed twice with triadimefon 25 W.P. at dosages
    from 125 to 250 g a.i./ha. Grains of oats, rye and barley did not
    contain residues of triadimefon or triadimenol, whereas grains of
    wheat contained up to 0.06 mg/kg triadimefon and 0.15 mg/kg
    triadimenol 35 and 42 days after last treatment. Straw from oats, rye,
    wheat and barley contained from <0.05 to 1.24 mg/kg triadimefon
    (single value) 35 days after last treatment, and the corresponding

    figures for triadimenol were from <0.1-1.5 mg/kg. The highest residue
    (1.67 mg/kg) of the total of triadimefon and triadimenol was found in
    a sample of straw from rye.

    Foods of Animal Origin

         In a feeding experiment, cattle were fed a 1:1 mixture of
    triadimefon and triadimenol equal to a total of 25, 75 and 250 mg/kg
    in feed for a period of 28 days. At the end of this period, the
    animals were slaughtered and tissues and milk were analysed for total
    residues of triadimefon and metabolites. Total residues from tissues
    of liver, kidney, muscle and fat and from milk are given in Table 4.
    All tissues, except muscle from the 25 mg/kg experiment, had
    measurable residues. Average values for three animals within a group
    showed an almost linear relationship with feeding level for residues
    in a given tissue.

         Milk showed a similar relationship. Average residues in muscle
    from the three feeding levels ranged from <0.01 to 0.03 mg/kg, fat
    from 0.02 to 0.17 mg/kg, liver from 0.08 to 0.74 mg/kg, kidney from
    0.36 to 1.29 mg/kg and milk from 0.07 to 0.05 mg/kg (Kruplak &
    Weissenburger 1981a).

         In another feeding experiment hens (four birds per interval) were
    fed daily rations containing equal amounts of triadimefon and
    triadimenol at total levels of 10, 25, 75 and 250 mg/kg in feed for 29
    days, after which they were slaughtered. All tissues and late-interval
    egg samples from each hen treated with 250 mg/kg were analysed for
    total residues of triadimefon, including free and conjugated
    metabolites. Average residues were as follows, liver 1.11 mg/kg, eggs
    0.03 mg/kg; fat 0.10 mg/kg; skin 0.09 mg/kg; gizzard 0.07 mg/kg and
    muscle 0.02 mg/kg. Duplicate liver and egg samples from hens fed 10,
    25 and 75 mg/kg all showed measurable residues, Liver and egg residues
    from hens fed the lowest dose (10 mg/kg) averaged 0.03 and 0.027
    mg/kg, respectively. Results from the experiment are presented in
    Table 5 (Kruplak & Weissenburger 1981b).

    FATE OF RESIDUES

    In Water

         Using a standardized test, the stability of triadimefon in water
    was investigated with thin-layer chromatography and measurement of the
    14C-activity of the active ingredient. At pH 3, 6 and 9 and a
    temperature at 22C the half-lives were found to be more than one
    year. From an experiment on the stability in water at 45C the 
    half-life was calculated to be about eight years (Wilmes 1982).


        Table 3    Residues of Triadimefon and triadimenol from Supervised Trials on Cereal Plants

                                                                                                                                         

    Crop               Dose a.i.          No.                                   Residue (mg/kg)                              Country
                       g/ha               Appl.    Day           Triadimefon                     Triadimenol
                                                           range            average        range             average
                                                                                                                                         

    Cereals

    Oats               Bayleton 25 WP     2                                                                                  FRG
    Green Forage       125 - 130                   14      n.d. - 0.06      < 0.05 (3)     < 0.1 - 0.26      0.15 (3)
                                                   28      n.d. - 0.05      < 0.05 (3)     0.1 - 0.31        0.19 (3)

    Straw                                          35      n.d. - < 0.05    < 0.05 (3)     < 0.1 - 0.29      0.10 (3)
                                                   42      n.d. - < 0.05    < 0.05 (3)     < 0.1 - 0.58      0.25 (3)

    Ears                                           14      n.d.             n.d. (3)       < 0.1 - 0.30      0.18 (3)
                                                   28      n.d.             n.d. (3)       n.d. - 0.30       0.10 (3)

    Grain                                          35      n.d.             n.d. (3)       n.d.              n.d. (3)
                                                   42      n.d.             n.d. (3)       n.d.              n.d. (3)

    Eye                Bayleton 25 WP     2                                                                                  FRG
    Green Forage       125 - 130                   14      < 0.05 - 0.20    0.12 (3)       0.11 - 1.5        0.81 (3)
                                                   28      0.05 - 0.12      0.08 (3)       n.d. - 1.2        0.68 (3)

    Straw                                          35      < 0.05 - 0.24    0.15 (3)       0.12 - 1.5        0.91 (3)
                                                   42      0.06 - 0.18      0.10 (3)       0.17 - 1.31       0.81 (3)

    Ears                                           14      < 0.05 - 0.20    0.10 (3)       < 0.1 - 0.41      0.28 (3)
                                                   28      n.d.             n.d. (3)       n.d. - 0.33       0.11 (3)

    Grain                                          35      n.d.             n.d. (3)       n.d. - <0.1       < 0.1 (3)
                                                   42      n.d.             n.d. (3)       n.d.              n.d. (3)
                                                                                                                                         

    Table 3  (Continued)

                                                                                                                                         

    Crop               Dose a.i.          No.                                   Residue (mg/kg)                              Country
                       g/ha               Appl.    Day           Triadimefon                     Triadimenol
                                                           range            average        range             average
                                                                                                                                         

    Wheat              Bayleton 25 WP                                                                                        FRG
    Stems/Straw        125 - 250                   14      n.d. - 0.88      0.15 (9)       < 0.08 - 0.71     0.39 (9)
                                                   28      n.d. - < 0.04    < 0.04 (8)     < 0.08 - 0.71     0.29 (8)
                                                   35      n.d. - < 0.04    < 0.04 (9)     0.12 - 1.29       0.43 (9)
                                                   42      n.d. - < 0.04    < 0.04 (9)     0.15 - 0.86       0.41 (9)

    Wheat
    Ears/Grain                                     14      0.093 - 0.35     0.21 (9)       0.10 - 0.59       0.24 (9)
                                                   28      n.d. - 0.06      < 0.04 (8)     n.d. - 0.18       0.12 (8)
                                                   35      n.d. - 0.06      < 0.04 (9)     n.d.- 0.10        0.12 (9)
                                                   42      n.d. - < 0.04    < 0.04 (9)     n.d. - 0.15       < 0.1 (9)

    Barley

    Green Forage       Bayleton EC.       2        8       0.09-0.12        0.10(2)        0.91-1.00         0.96(2)         Denmark
                                25
                       125

    Straw                                 2        57      <0.02-<0.02      <0.02(2)       0.20-0.25         0.23(2)

    Ears                                  2        41      <0.01-<0.01      <0.01(2)       <0.02-<0.02       <0.02(2)

    Grain                                 2        57      <0.01-<0.01      <0.01(2)       <0.02-<0.02       <0.02(2)
                                                                                                                                         

    Table 4   Total Triadimefon Residues in Bovine Tissues and Milk

                                                                                                                            

    Feeding                              Average of total residues (mg/kg) and range ( )
    level               Liver               Kidney              Muscle              Fat                 Milk
                        N=3                 N=3                 N=3                 N=3                 N=9
                                                                                                                            

    25 mg               0.08                0.36                <0.01               0.02                0.007
                        (0.07-0.09)         (0.30-0.41)                             (0.02-0.02)         (0.004-0.014)

    75 mg               0.27                0.54                0.01                0.07                0.024
                        (0.27-0.29)         (0.26-0.79)         (<0.01-0.02)        (0.05-0.09)         (0.014-0.035)

    250 mg              0.74                1.29                0.03                0.17                0.050
                        (0.40-1.00)         (0.79-2.27)         (0.03-0.04)         (0.11-0.21)         (0.026-0.077)
                                                                                                                            

    Table 5   Total Triadimefon Residues in Poultry and Eggs

                                                                                                             

                                  Total residues (mg/kg) N = 2
    Feeding                       Liver               Eggs (27-28 days)
    level
                                                                                                             

    10 mg                         0.02 - 0.05         0.02 - 0.03
    25 mg                         0.08 - 0.09         0.04 - 0.07
    75 mg                         0.18 - 0.29         0.09 - 0.22
                                                                                                             

                                  Average of total residues (mg/kg), and range ()

                        Muscle         Fat            Liver          Skin           Gizzard        Eggs
                                                                                                             

    250 mg              0.02           0.10           0.11           0.09           0.07           0.93
                        (0.01-0.02)    (0.05-0.15)    (0.91-1.41)    (0.04-0.20)    (0.06-0.09)    (0.70-1.19)
                                                                                                             
    
    In Plants

    Rotational crops

         Uptake of soil residues by rotational crops has been studied by
    Fredrickson & Thornton (1982). Triadimefon-benzene ring-14C was
    applied to winter wheat at a dosage equal to 8 oz/acre (ca. 0.5
    kg/ha). At 28 days after treatment, the wheat was removed and kale,
    beetroots and spring wheat were grown as rotational crops to maturity.
    At 119 days after treatment, similar crops were planted and grown to
    maturity. Total radiocarbon residues were determined in crops sampled
    at various intervals, including harvest. Residues were highest in
    wheat forage (0.12 mg/kg) and wheat heads (0.10 mg/kg) in the 28-day
    rotational crops. Residues in the 28-day kale crop ranged from 
    0.02-0.08 mg/kg, while residues in beetroots were less than 0.01
    mg/kg. Residues in the 119-day rotational crops were slightly lower.

         The distribution of compounds with carbon radioactivity in 
    119-day rotational crops of kale, beet tops and wheat straw was
    investigated by thin-layer chromatography. As concentrations were low,
    near the limit of determination, a final identification was not
    possible, but it was tentatively concluded that mainly triadimenol but
    also triadimefon and 4-chlorophenol were present in the 119-day
    rotational crops. In wheat straw, about 30 percent of the carbon
    radioactivity came from free triadimenol, triadimefon and 
    4-chlorophenol and, in addition, 20 percent came from conjugated
    triadimenol and 4-chlorophenol.

    In grapes

         In an experiment on uptake and translocation of triadimefon in
    grape plants 14C-triadimefon was applied on the leaf surface and its
    movement observed by autoradiography. The active ingredient moved
    rapidly into the uppermost epidermal layers, from where it was
    absorbed into the tissues. As a result, washing with water only 45
    min. after foliar application could not recover more than half of the
    applied dose. When applied to young, unlignified stem tissue, the
    active ingredient also was transmitted into the leaves above.
    Translocation from the vascular system to the adjacent tissue was more
    pronounced in young leaves than in old ones (Kraus 1981).

    In barley

         Shoots of barley (stage 6) grown in a greenhouse were treated
    with 14C-triadimefon at a dosage of 500 g a.i/ha, which is four times
    higher than the recommended dose at 66 days after treatment (stage
    10), plants were harvested and analysed for residues of triadimefon
    and its metabolites, free as well as conjugated. The results from the
    experiment are presented in Table 6 (Rouchaud et al. 1982). In a
    supplementary study the same authors investigated the metabolism of
    triadimefon in grain and straw of ripe barley treated with 
    14C-triadimefon at same time and dosage as in the above-mentioned
    study and with a second treatment 76 days after first treatment, with


        Table 6   Residues of Triadimefon and Metabolites in Barley

                                                                                                                  

                                   Green plants                      Grains                         Straw
    Application:                    (stage 10)                     (stage 11.4)                  (stage 11.4)
    Compound                         1 x 500 g                      2 x 500 g                      2 x 500 g
                                                                                                                 
                               % of total     mg/kg          % of total      mg/kg         % of total       mg/kg
                               radioactivity                 radioactivity                 radioactivity
                               in plant                      in plant                      in plant
                                                                                                                  

    Triadimefon, free             9.7         1.00              6.0           0.12            2.3           0.70

    Triadimenol, free            20.3         2.10              9.5           0.19            5.4           1.61

    Triadimenol, conjug.          8.0         0.80              3.5           0.07            0.3           0.10

    4-chlorophenol, conjug.      35.1         1.58             15.5           0.13            3.8           0.49

    Residues insolub, in         13                            61                            84
    acetone-water (3.3+1)
                                                                                                                  
    
    a dosage equal to that of the first treatment. The ripe plants were
    harvested 42 days after last treatment and grains and straw were
    analysed. The results from this investigation are also presented in
    Table 6 (Rouchaud et al. 1981).

    In Wheat

         Plants of spring and winter varieties of wheat were sprayed with
    14C-triadimefon at a dosage equivalent to 8 oz a.i./acre (ca. 0.5
    kg/ha). Forage samples were taken 0, 7, 14 and 28 days after
    treatment. The wheat was harvested 84 and 74 days, respectively, after
    treatment. Analytical results were generally parallel for the two
    varieties. By an exhaustive extraction procedure, mainly methanol and
    methanol/water mixtures, 95.7 to 99.8 percent of the radioactive
    residues were extracted. Triadimefon was metabolized with initial
    half-lives of 8 and 18 days for spring and winter wheat, respectively.
    Residues in forage and straw were converted primarily to triadimenol
    plus a number of minor apolar metabolites and their polar glycoside
    conjugates. Identification was obtained for 81.6 percent of the total
    activity. Residues in grains were low (0.8 mg/kg) (Morgan & Lenz
    1982).

    Metabolism

         The ratio of the two diastereomeric forms of triadimenol,
    produced by the reduction of triadimefon in various fungi, was
    studied. The reduction of triadimefon in fungi seems to be a
    concentration-dependent process, the virtual irreversibility of which
    has been proved. Not only the degree of triadimefon reduction, but
    also the ratio of the triadimenoldiastereomers produced, was
    characteristic for each of the fungal species. A direct correlation
    between the production of the more active diastereomeric form and the
    sensitivity of the fungal species to triadimefon was observed
    (Gasztonyi 1981).

    National Maximum Residue Limits

         The following national maximum residue limits (MRLs) for
    triadimefon and triadimenol were reported to the Meeting.

                                                                                              

    Country             Crop                         Maximum residue     Preharvest
                                                     limit               interval
                                                     (mg/kg)             (days)
                                                                                          

    The Netherlands     Apple                        0.1                 14

                        Grain, milk and milk         0.05                grain: 42
                        products, meat and
                        meat products

    Sweden              Fruit and vegetables         0.5                 28 days
                                                                         cucumber: 4 days

    United States       Wheat grain                  1                   21
                        Wheat, green forage          15                  21
                        Wheat straw                  5                   21
                        Barley grain                 1                   21
                        Barley, green forage         15                  21
                        Barley straw                 5                   21
                        Meat, fat and meat by-       1
                        products of cattle,
                        goats, horses and sheep

                        Eggs, milk, meat, fat        0.04
                        and meat by-products of
                        poultry and pigs

                        Wheat, milled fractions      4
                        (except flour)

                        Barley, milled fractions     4
                        (except flour)
                                                                                          
    
    APPRAISAL

         In response to requests from the 1979 Meeting, information was
    received on residues of triadimefon and its main metabolite,
    triadimenol, in animal tissues, milk and eggs after feeding studies on
    cattle and hens. Residue data were also received on a large number of
    supervised trials on fruit, beets, coffee and cereals.

         Residue data from trials on apples, grapes and berries
    supplemented those received at the 1979 Meeting and confirmed the
    residue limits recommended. New data from trials on preharvest
    treatments of coffee, pears and fodder beets and postharvest treatment
    of pineapples enabled the Meeting to recommend residue limits for
    these commodities.

         At the 15th Meeting of the Codex Committee on Pesticide Residues
    a need was expressed to raise residue limits for grains, and
    especially for barley, and also for barley and wheat straw. The
    Meeting has received new data from trials on cereals, including
    residue data on grains and straw from barley and wheat. This new data
    did not, however, support raising the limits for grains of barley,
    oats and rye, whereas some data would support raising the limits for
    wheat grains. The data received did not support higher limits for
    straw.

         Data from feeding studies on cattle and hens were carried out at
    unrealistically high feeding levels, but even the lowest of these
    levels (25 mg/kg in feed for cattle and 10 mg/kg in feed for hens)
    showed that residues in muscle, fat and milk from cattle and liver and
    eggs from hens were well within the residue limits recommended by the
    1979 Meeting. As the experiment has demonstrated an almost linear
    relationship with the feeding levels for residues in tissues, the
    residues would be expected to be much lower from the use of feed with
    lower and more realistic feeding levels.

         A rotational crop study indicated the presence of triadimefon and
    mainly triadimenol in subsequent crops, especially in wheat grown in
    fields treated with triadimefon in which the benzene ring was marked
    with 14C.

         A study was made on uptake and distribution in grape plants
    through the foliar surface, which confirms previous studies on other
    plants. Studies have also been made on metabolism in barley and wheat,
    which confirm that triadimenol is the main metabolite in plants, but
    also revealed the presence of glycoside conjugates of triadimenol and
    4-chlorophenol in green plants, grains and straw.

    RECOMMENDATIONS

         The Meeting examined residue data from supervised trials on a
    number of crops. From these data the Meeting was able to confirm
    existing residue limits and recommended new temporary maximum residue
    limits below which residues are likely to occur, when triadimefon is
    used according to present practice and the reported intervals are
    observed. The limits refer to the sum of the parent compound
    triadimefon and its major metabolite triadimenol.

         Since MRLs now have been recommended for the major pome fruits at
    a level of 0.5 mg/kg, the Meeting proposed that this figure could be
    extrapolated to the whole commodity group and a group MRL recommended.

                                                                     

    Crop                  Temporary        Preharvest intervals
                          MRL              on which recommendations
                                           are based (days)
                                                                     

    Pome fruit            0.5              14
    Pineapple             2                postharvest
    Fodder beet           0.1**            35
    Fodder beet leaves    0.1**            35
    Poultry meat          0.1**
    Wheat                 0.2 (increase    35
                               from 0.1)
                                                                     

    **   Level at or about the limit of determination.


    REFERENCES - RESIDUES

    Fredrickson, D.R. & Thornton, J.S. Residues in rotational crops
    1982      following treatment of a target crop with Bayleton-14C.
              Mobay report No. 80 606 submitted to FAO by Mobay Chemical
              Corporation. (Unpublished)

    Gasztonyi, M. The diastereometric ratio in the triadimenol produced by
    1981      fungal metabolism of triadimefon, and its role in fungicidal
              selectivity. Pestic. Sci., 12: 433-438.

    Kraus, P. Studies on uptake and translocation of Bayleton in grape
    1981      plants. Bayer Pflanzenschutz-Nachr. 34: 197-212.

    Kruplak, J.F. & Weissenburger, B. Effect of feeding Bayleton and the
    1981a     metabolite KWG 0519 (BaytanTM) to dairy cattle - Total
              residue. Mobay report No. 69 930 submitted to FAO by Mobay
              Chemical Corporation. (Unpublished)

    Kruplak, J.F. & Weissenburger, B. Effect of feeding Bayleton and the
    1981b     metabolite KWG 0519 (BaytanTM) to poultry - Total residue.
              Mobay report No. 80 281 submitted to FAO by Mobay Chemical
              Corporation. (Unpublished)

    Morgan J.G. & Lenz, M.F. Metabolism of Bayleton in wheat. Mobay report
    1982      No. 80 293 submitted to FAO by Mobay Chemical Corporation.
              (Unpublished)

    Rouchaud, J., Moons, C. & Meyer, J.A. The products of metabolism of
    1981      14C-triadimefon in the grain and in the straw of ripe
              barley. Bull. Environ. Contam. Toxicol., 27: 543-550.

    Rouchaud, J., Moons, C. & Meyer, J.A. Metabolism of 14C-triadimefon
    in
    1982      barley shoots. Pestic. Sci., 13. 169-176.

    Wilmen, R. Fate/behaviour of crop protection products in water. Bayer
    1982      AG, PF-A/CE-PIQ-ENA. Report submitted to FAO by Mobay
              Chemical Corporation. (Unpublished)


    See Also:
       Toxicological Abbreviations
       Triadimefon (Pesticide residues in food: 1979 evaluations)
       Triadimefon (Pesticide residues in food: 1981 evaluations)
       Triadimefon (Pesticide residues in food: 1984 evaluations)
       Triadimefon (Pesticide residues in food: 1985 evaluations Part II Toxicology)