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    PESTICIDE RESIDUES IN FOOD - 1982


    Sponsored jointly by FAO and WHO






    EVALUATIONS 1982





    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, 23 November - 2 December 1982

    Food and Agriculture Organization of the United Nations
    Rome 1983


    ETHIOFENCARB

    CHEMICAL STRUCTURE 1

    Explanation

         Ethiofencarb was first evaluated by the 1977 Joint Meeting on
    Pesticide Residues (FAO/WHO 1978)1 and a temporary ADI was allocated
    based on the no-effect level observed in a 4-week oral study on the
    rat.

         The 1977 JMPR requested the submission of the results of the
    reproduction study in progress for the 1978 JMPR. Since the required
    study was not available, the 1978 and 1980 JMPRs extended the
    temporary ADI until 1982.

         The required reproduction study, a  Salmonella/microsome
    mutagenicity test, and an embryotoxicity and teratogenicity study have
    been submitted and are summarized in the following monograph addendum.

    EVALUATION FOR ACCEPTABLE DAILY INTAKE

    TOXICOLOGICAL STUDIES

    Special Studies on Reproduction

         Groups of rats (10 male and 20 female, Long Evans FB 30 strain,
    rats/group) were fed ethiofencarb (technical grade, purity not stated)
    in the diet at dosage levels of 0, 330 and 3 000 ppm and subjected to
    two-litter per generation, three-generation reproduction study. The
    rats were treated with the test compound throughout the study,
    including mating, gestation and lactation. The adult rats were weighed
    weekly. The body weights of the pups were measured immediately after
    delivery, five days after birth, one week after the birth, and
    thereafter at weekly intervals. The rats selected for the study were
    fed from 45 days of age until sexually mature (ca. 100 days), when
    they were mated to initiate the study.

              

    1  See Annex 2 for WHO and FAO documentation.

         During the mating period, two female rats were housed together
    with one male rat for 21 days. The male rats were rotated so that each
    female was paired with three different males for a period longer than
    one oestrous cycle. Immediately after the pups were delivered, their
    number and weights were recorded. Litters containing more than 10 pups
    were reduced on the fifth day after delivery to 10 pups each, 
    whereupon the weights of these litters were again measured. The pups
    were nourished for up to 4 weeks, during which time they were weighed
    weekly; then the offspring of each first mating (F1a, F2a, F3a
    generation) were sacrificed, as were the pups of the F3b generation.
    The parental animals were again mated to provide a second litter,
    which became the parental animals for the second generation.

         Again pups were weaned after 4 weeks and reared up to an age of
    100 days. Ten males and 20 females from the second litters (F1b, F2b)
    were selected for the succeeding generation.

         Gross and histopathological examinations were performed on major
    organs and tissues of one male and one female pup (4 weeks old) of the
    F3b generation from each of 10 mothers in each group.

         In parental generation (Fo, F1b, F2b), there were no clinical
    symptoms and no mortality attributable to treatment (some animals in
    the control and treated groups died of pneumonitis). Body weight
    curves of females of the F0, F1b and F2b generation, at 3 000 ppm
    and of males of the F2b at 3 000 ppm were lower than that of control
    group. Pregnancy rate was lower than the control in F0 animals at
    first mating (F0-F1a) in the 1 000 and 3 000 ppm group, comparable
    to the control in the F1b - F2a- F1b- F2b and F2b-F3a at all
    levels, and again lower than control in the F2b- F3b at 3 000 ppm.
    With regard to litter size (average number of pups/litter) and
    viability index (5-day survival rate), a lower viability index in the
    F2b at 3 000 ppm, a lower litter size and viability index in the F3a
    and F3b at 3 000 ppm with slight effects also at 1 000 ppm were
    observed. Lactation rates were impaired in the F3a and F3b at
    3 000 ppm. Average body weight of pups at birth were lower than the
    control in the F1b at 1 000 ppm and 3 000 ppm, in F2a and F2b at
    3 000 ppm, and in F2a and F3b at 3 000 ppm. Growth curves for the
    pups during lactation were lower than the control in F1b at
    1 000 ppm, in F2a at 3 000 ppm and in F2b at 1 000 and 3 000 ppm
    (with a marginal less significant effect at 330 ppm).

         Pups observed grossly immediately after birth and during the
    lactation period did not reveal any signs of malformations.

         At necropsy, gross and histopathological examinations did not
    provide any indication of treatment-related alterations in the tissues
    of the pups of the F3b generation at all levels.

         On the basis of the data, the no-effect level may be considered
    330 ppm with respect to the reproductive performance (Löser 1979).

    Special Studies on Embryotoxicity and Teratogenicity

         Groups of pregnant Wister KFM-Han rats (25 mated female
    rats/group) were treated by intubation with ethiofencarb (94.6%
    purity) in 2% carboxymethylcellulose Na+ salt aqueous solution at 0,
    12.5, 25 and 50 mg/kg bw/day on day 6 through 15 of gestation. The
    dams were sacrificed on day 21 and foetuses removed by caesarean
    section. Foetuses were examined for external, skeletal and internal
    malformations. No dam died in any group throughout the experiment. No
    signs of toxicity or clinical symptoms were observed in the females of
    all groups. There were no significant differences between the control
    and treated groups with respect to mean food consumption. A slight
    reduction in the mean corrected body weight gain of the 25 mg/kg/day
    group (3%) compared to the control was observed. (Corrected body
    weight gain = (final weight - uterus weight) - (weight gain on day 6;
    in % weight on day 6).)

         No foetolethality was observed in any group. There were no
    significant differences between the control and treated groups with
    respect to the numbers of pregnant females, implantations, abortions,
    embryonal deaths (resorptions), number of live foetuses and their
    distribution within the uterus horns, mean weight of live foetuses and
    sex ratio of foetuses. No malformations or anomalies were seen at
    the external inspections and in the skeletal investigations
    (2/3 foetuses). There were no relevant differences in the skeletal
    development between the control and treated groups. Internal
    malformations were reported in the control group (2 foetuses with
    dilated aquaeductus cerebri silvii and 2 foetuses with dilated kidney
    pelvises), in the 25 mg/kg/day group (one foetus with dilated kidney
    pelvises, one foetus with a medial dystopia of the right undescended
    testes and one foetus with dilated aquaeductus cerebri silvii) and in
    the 50 mg/kg/day group (one foetus with dilated kidney pelvis). These
    findings are not believed to be related to treatment, as they occur
    spontaneously in untreated rats of this strain. On the basis of the
    data, ethiofencarb did not reveal embryotoxic and teratogenic activity
    (Becker 1981).

    Special Studies on Mutagenicity

     Salmonella/microsome test

         An evaluation of the mutagenic potential of ethiofencarb was
    performed according to the standard Ames assay. Strains of
     Salmonella typhimurium (TA 1535, TA 1537, TA 100, TA 98), with and
    without a metabolic activation system (S-9 mix) derived from the liver
    of Sprague-Dawley rats treated with a single intraperitoneal dose of
    Arochlor 1254, were treated at concentrations of ethiofencarb (93.1%
    purity) up to and including 2 500 µg/plate. Positive controls were
    cyclophosphamide for TA 1535 and TA 100, and trypaflavin for TA 1537
    and TA 98. Negative controls were the respective solvents (i.e.

    dimethyl-sulphoxide for ethiofencarb and trypaflavin and demineralized
    water for cyclophosphamide). Four plates/strain/dose/substance were
    used. Two plates/group were used to determine the total number of
    bacteria. Three further tests with TA 98 and TA 1535 and TA 100 were
    repeated at concentrations of 3 000, 3 750 and 2 500 µg of
    ethiofencarb/plate, respectively. A reproducible dose-dependent
    increase in the number of mutants to a level double than that recorded
    for the negative control, obtained with at least one strain, is
    considered to be a positive result.

         At concentrations up to and including 3 750 µg/plate ethiofencarb
    did not reveal a bacteriotoxic effect.

         With S-9 mix, a slight dose-dependent increase of number of
    mutants (but less than double that of the negative control), was seen
    on TA 100 in the main test and confirmed in the repetition test. A
    similar finding on TA 98 was not confirmed in the repetition test.

         Without S-9 mix, increases greater than double that of the
    negative control were seen on TA 1535 and TA 100 in the main test and
    confirmed in the repetition test. The positive controls increased the
    number of mutants well above the double of those recorded for the
    negative controls, and thus demonstrated the sensitivity of the system
    and the activity of S-9 mix. The  Salmonella/microsome test
    revealed a weak although definite mutagenic activity of ethiofencarb
    on  S. typhimurium TA 1535 and TA 100 (Herbold 1979).

    COMMENTS

         Ethiofencarb was last evaluated for an acceptable daily intake
    for man by the 1977 JMPR and a temporary ADI was allocated. The
    submission of the results of reproduction studies in progress was
    requested.

         No-effect levels could be assessed with respect to newly
    submitted reproduction and teratogenicity studies.

         Although an Ames test showed slight mutagenic activity to
     S. typhimurium (strains TA 1535 and TA 100), a dominant lethal study
    in male mice indicated no mutagenic activity.

         The evaluated data permitted the establishment of an ADI.

    TOXICOLOGICAL EVALUATION

    Level Causing no Toxicological Effect

    Rat : 10 mg/kg bw/day

    Dog : 1 000 ppm in the diet, equivalent to 25 mg/kg bw/day.

    Estimate of Acceptable Daily Intake for Man

    0 - 0.1 mg/kg bw.

    FURTHER WORK OF INFORMATION

    Desirable

         Additional mutagenicity studies to clarify the mutagenic
    potential.

    REFERENCES

    Becker, H. Embryotoxicity and teratogenicity study with HOX 1901 in
    1981      rats. Final Report No. R2048 (Project No. 000033) from
              Research and Consulting Company, Ltd., Itingen
              (Switzerland), submitted to the World Health Organization by
              Bayer, F.R.G. (Unpublished)

    Herbold, B. HOX 1901.  Salmonella/microsome test for detection of point
    1979      mutagenic effects. Report No. 8559 (Study No. HOX 1901/003)
              from Institut für Toxicologie, Bayer. Submitted to the World
              Health Organization by Bayer, F.R.G. (Unpublished)

    Loser, E. HOX 1901. Multi-generation reproduction study on rats.
    1979      Report No. 8403 from Institut für Toxicologie, Bayer,
              submitted to the World Health Organization by Bayer, F.R.G.
              (Unpublished)

    ETHIOFENCARB

    CHEMICAL STRUCTURE 2

    Explanation

         Ethiofencarb was evaluated by the 1977, 1978 and 1981 Joint
    Meetings.1 Further residue data from supervised trials on crops on
    which ethiofencarb is known to be used were considered desirable. 
    Additional information was provided on residues in crops treated
    directly and in rotational crops as well as on the fate of residues.

    RESIDUES IN FOOD AND THEIR EVALUATION

    RESIDUES RESULTING FROM SUPERVISED TRIALS

         Trials were carried out on several crops in the Federal Republic
    of Germany (FRG), United Kingdom (U.K.) and the U.S. (Bayer AG
    1978-79; Bayer UK Ltd. 1977-1980). The analytical methods used
    measured ethiofencarb sulphone, an oxidation product of ethiofencarb
    and its sulphoxide. The limit of determination was 0.01-0.05 mg/kg.

    Vegetables

         Croneton SL or 500 EC was used at rates of 0.3-0.5 kg a.i./ha in
    the trials on broad beans, Brussels sprouts, kale, savoy cabbage and
    lettuce. Potatoes were treated one to three times with Croten EC at
    rates from 0.3 to 0.5 kg a.i./ha. Fresh potatoes were sampled on the
    day of treatment and thereafter until 51 days post-treatment. Croneton
    FE granules were applied at planting at dosage rates of 1.1-1.5 kg
    a.i./ha, Residues in the tubers were below 0.05 mg/kg in all samples.
    The results and details of the experiments are given in Table 1.

    Cereal Grains

         Oat and wheat seeds were treated with Croneton 40 DS at a rate of
    180 g a.i./100 kg seed. Oat plants were sampled regularly beginning on
    day 61 after treatment. The grains were analysed from 143 to 199 days
    after treatment. Neither the plants nor the grains contained
    detectable residues.

              

    1  See Annex 2 for FAO and WHO documentation.

        Table 1.  Residues Resulting from Supervised Trials with Ethiofencarb

                                                                                                                                            

                                    Application                                Residues (mg/kg) at intervals (days) after
                                                                               application 1
    Crop          Country   Year          Rate       Formulation  Interval                                                                  
                                    No.   (kg. a.i                (days)
                                          /ha)                                 0      1      4      7      11-14  21     34     51   143-178
                                                                                                                                            

    Broad beans   U.K.      1977    1     0.5        EC           -                                       0.024
    pods                                                                                                  0.024

    Broad beans   U.K.              1     0.5        EC           -                                       0.037
    pods          U.K.                                                                                    0.11

    Brussels      FRG       1978    2     0.3        SL           8           0.29   0.18   0.2    0.22

    sprouts       FRG       1978    2     0.3        SL           7           0.16   0.14   0.34   0.2
                  FRG       1978    2     0.45       SL           7           0.9    1.08   0.81   0.83

    Kale          FKG       1979    2     0.3        EC           14          3.3    5.1    1.1    0.76

    Lettuce       FKG       1978    2     0.3        SL           8           5.6    5.4    1.2    0.8

    Lettuce       FRG       1978    2     0.3        SL           7           5.2    4.4    2.4    2.2

    Savoy cabbage FRG       1978    2     0.3        SL           8           1.1    1.2    0.43   0.47

    Potato        FRG       1979    3     0.5;0.4    EC           14          0.07          0.07   0.07   0.08
                                          0.3
                  FRG       1979    3     9.5;0.4    EC           14         <0.05         <0.05         <0.05  <0.05  <0.05
                                          0.3                     13
                                                                                                                                            

    Table 1.  (con't)

                                                                                                                                            

                                    Application                                Residues (mg/kg) at intervals (days) after
                                                                               application 1
    Crop          Country   Year          Rate       Formulation  Interval                                                                  
                                    No.   (kg. a.i                (days)
                                          /ha)                                 0      1      4      7      11-14  21     34     51   143-178
                                                                                                                                            
                  U.K.      1977    1     0.75
                  U.K.      1977    1     0.5        EC                                                   0.034               <0.01
                  U.K.      1977    1     0.5        EC                                                   0.032
                  U.K.      1977    3     0.5        EC           23,15                                   0.016
                  U.K.      1977    1     1.13       FE                                                                               0.024
                  U.K.      1977    1     1.5        FE                                                                               0.022
                  U.K.      1979    1     1.13       FE                                                                              <0.05
                  U.K.      1979    1     1.5        FE                                                                              <0.05
                                                                                                                                            

    1  Sum of parent compound, its sulphoxide and sulphone.
        Sugarbeet

         Supervised trials on sugarbeet were carried out in the U.K.
    during three years. The sugarbeet plants were treated With Croneton
    EC at a dosage rate of 0.5 kg a.i./ha 2 or 3 times 18-26 or 81 days
    apart. The roots and tops or foliage were sampled and analysed
    separately. The residue on roots ranged from <0.01 to 0.026 or to
    <0.05 mg/kg at intervals up to 112 days after treatment. The residues
    in the tops were 2 mg/kg at 25 days, 0.36-0.39 mg/kg at intervals from
    41 to 73 days and 0.055 mg/kg at 112 days after last application.

    Rotational Crops

         Peas planted as rotational crop in sandy soil received broadcast
    treatment with ethiofencarb. The dosage ranged from 0.25 kg a.i./ha to
    4.5 a.i./ha. Planting was from 29 to 362 days after application.
    Samples were taken from 61 to 93 days after planting. Regardless of
    the dosage and time elapsed, the residues were <0.01 or <0.02 mg/kg,
    the limit of determination in all samples with a single exception. In
    the latter case, 0.06 mg/kg residue was in the gree vine sampled 61
    days after planting in a soil which had been treated 29 days earlier
    (Mobay undated). Maize, grown in three fields was treated with
    ethiofencarb at rates of 1.1, 2.2, 4.5 kg a.i./ha. Sowing was 29 days
    after soil treatments. Green forage samples were taken at intervals
    from 32-75 days after sowing. The kernel was sampled at day 75.
    Residues in green forage ranged from 0.01 to 0.23 mg/kg, while one
    kernel sample contained 0.01 mg/kg and the other two less than
    0.01 mg/kg.

    FATE OF RESIDUES

    In Plants

         In greenhouse trials, Arylmate 50% EC (25 mg a.i./plant) was
    sprayed on potatoes at the 12-leaf stage by foliar application or the
    diluted emulsion was added to the soil surface in the pot. After
    sampling, the adhering soil was removed by washing from the plants and
    the green portions (leaves and stems) and the roots or tuber were
    analysed separately. Soil samples were taken respectively from the
    upper 3 cm layer and from the 0-3, 3-6, 6-11 cm layers one day and 35
    days after drench application (Takase and Yashimoto 1979). The
    concentration of total residues was 54.6 mg/kg in the green portion 30
    minutes after spraying. Ethiofencarb was rapidly converted to its
    sulphoxide and sulphone in plants and soil. Rapid oxidation may also
    occur during the analytical procedure; however 85% of ethiofencarb
    could be recovered under the analytical conditions.

         The level of total residue and the ratio of sulphoxide and
    sulphone derivatives in potato plants are shown in Table 2. The
    residue level in the roots or tuber were much lower. The concentration
    maximum was observed 7 days after both applications when it was ca.
    2.8 mg/kg and 1 mg/kg following foliar and drench applications
    respectively. The residue level declined thereafter, and it was in the
    range of 0.07-0.38 mg/kg 35 days after application. The major part of
    the residue in the tuber was ethiofencarb sulphoxide while the parent
    compound was present in small amounts in a few cases only.

        Table 2.  Ratios of Ethiofencarb and its Metabolites in Potato
                                                                                               

    Application   Level (mg/kg) of           Percentage ratio of compounds
    Interval      total residue                                                                
    (days)        foliar (F)    Drench (D)     S                  SO               SO2
                                             F      D          F      D         F      D
                                                                                               

    1             34.9          7.8          11.8   40.4       80.1    55.9     8.1    4.1
    2             38.7                       8.6               81.2             10.2
    4             28.3          41           0.7    7.0        84      82.9     15.3   10.1
    7             25.7          51.9         0      1.8        75.3    78.9     24.7   19.3
    14            13.7          19.6         0      0          55.5    80       44.5   20.3
    21            8.7           9.3          0                 47.1    64.2     52.9   35.8
    35            4.2           5.3          0                 27.8    52.1     72.2   47.9
                                                                                               

    1  Measured in green portions after foliar (F) and drench (D) application.
    
         Experiments were carried out to identify non-extractable residues
    in potato foliage (Dräger 1977). It was found that the non-extractable
    radioactivity, amounting to approximately 10% of the total residue,
    is attributable to the incorporation of the carbomyl 14C atom of
    ethiofencarb in the glucose molecule derived from the starch
    hydrolysis. Ethiofencarb was applied to Chinese cabbage at about the
    12-leaf stage by foliar application (Takase and Yashimoto 1978). One
    day after application, 89.7% of the applied ethiofencarb was
    recovered. The total residue, 46.2 mg/kg, consisted on 28.4%
    ethiofencarb, 69.7% sulphoxide and 1.9% sulphone derivatives. The
    parent compound disappeared rapidly and it was not detectable from
    the third day after treatment, when 93.4% of the total residue
    (36.4 mg/kg) was the sulphoxide derivative. The total residue
    gradually decreased while the ratio of sulphone to sulphoxide slowly
    increased. The total residue, consisting of 60.3% sulphoxide and 39.3%
    sulphone, was 18 mg/kg 38 days after treatment.

    In Soil

         The degradation of ethiofencarb in soil is slower than in plants.
    The half life of residues was found to be approximately 120 days in a
    soil of Ph 6 under natural field conditions. Residues were detectable
    only to a depth of 40 cm in contrast to the higher mobility indicated
    by laboratory experiments (Dräger 1977). The formation of sulphoxide
    is also slower in soil than in plants. The parent compound was still
    detectable 35 days after treatment; however, the major portion of the
    total residue was the sulphoxide. Distribution rates of ethiofencarb
    and its oxidative derivatives were found to be similar 35 days after
    either foliar or drench application (Takase and Yashimoto 1979).

    Under Field Conditions

         The behaviour of ethiofencarb was studied under normal farming
    practice on large scale. A 10 ha sugarbeet field, which was provided
    with a drainage system, was treated twice with ethiofencarb at a rate
    of 0.5 kg a.i./ha. Lactating dairy cattle were fed for 2 weeks with
    2x20 kg treated sugarbeet leaves containing 0.4 mg/kg residue. Winter
    wheat was sown after sugarbeet. Samples were taken from the treated
    plants, soil, rotational crops, collecting points of the drainage
    pipes, drinking water of a well situated 700 m from the field and from
    milk of treated cows. The sugarbeet leaves contained residues in the
    1 mg/kg range during the first few weeks, which declined to below
    0.2 mg/kg at the time of harvest. The sugarbeet roots did not contain
    measurable residues at harvest. Winter wheat was sown in a soil
    containing 0.04 mg/kg residue in the 0 to 40 cm soil layer. Residues
    amounting to 0.03 mg/kg were found only in the green plant samples
    taken 179 days after sowing. No residue was detectable in wheat
    samples taken later. The milk samples contained no measurable residue
    at any time (<0.05 mg/kg).

         The drainage water first appeared 7 months after the treatment of
    the field and contained residues ranging from 0.002 to 0.009 mg/kg
    during the next 6 months. The well water did not contain measurable
    residue in the period up to 1.5 year after the application of
    ethiofencarb. The residue in the soil declined to about 0.03 mg/kg
    within a year after the treatment.

    Light Stability

         Ethiofencarb undergoes rapid degradation under UV or natural
    sunlight either on silica gel plates or in a bi-distilled water
    solution. The half life on silica gel irradiated with sunlight-
    simulating fluorescent tubes was found to be 3 days. In water
    containing 0.5% acetonitrile 50% of the parent compound degraded
    under a mercury vapour lamp within 18-24 hours, while only 20%

    degraded under a sunlight-simulating lamp after 5 days. The
    degradation products identified in the water solution were the
    sulphoxide derivative and the 2-formylphenyl-N-methyl carbamate
    (Wilmes 1981).

    NATIONAL MAXIMUM RESIDUE LIMITS

         The maximum residue limits and preharvest intervals shown in
    Table 3 were reported to the Meeting.

    Table 3.  National Maximum Residue Limits for Ethiofencarb
                                                                        

                                                     Preharvest
    Country            Crop                          Interval      MRL
                                                     (days)      (mg/kg)
                                                                        

    Austria            Fruit,vegetables              7             7.0

    Bulgaria           Cotton, fruit,peppers,
                       (field grown and
                       under glass), tobacco         4

    Cyprus             Beet, cereals, citrus
                       fruit, pome fruit,
                       potatoes, stone fruit,
                       tobacco, vegetables           3-4

    Czechoslovakia     Field beans                   21
                       Vegetables                    14

    Denmark            Beets, cereals, fruit,
                       vegetables                    14

    France             Beets                         7
                       Cereals                       21
                       Fruit, vegetables             7             2.0

    German             Fruiting vegetables           4
    Democratic         Fodder crops, oilseeds,
    Republic           potatoes, sugarbeet,
                       feedstuffs                    7
                       Bulb vegetables, fruit,
                       legume vegetables,
                       officinals, root vegetables,
                       drift-treated food crops      14
                                                                        

    Table 3.  (con't)
                                                                        

                                                     Preharvest
    Country            Crop                          Interval      MRL
                                                     (days)      (mg/kg)
                                                                        

                       Brassicas, cereals,leafy
                       and stem vegetables           21
                       Food crops for infant
                       diet                          28

    Federal            Cherries, lettuce             4             10.0
    Republic           Apricot, artichoke,peach
    of Germany         Currants, plums                             5.0
                       Pome fruits                   4             3.0
                       Brassicas, excluding
                       cauliflower                   4             3.0
                       Eggplant                                    2.0
                       Broad beans, green beans      4             2.0
                       Cauliflower, cucumber                       1.0
                       Potatoes                      14            0.5
                       Sugarbeet                                   0.1
                       Other plants                                0.05

    Israel             Potatoes                      4 1
                       Peppers (green)               5
                       Apples, brassicas,
                       cauliflower, celery,
                       Chinese cabbage,
                       cucumber, eggplant,
                       zucchini                      7
                       Pecans                        60
                       Potatoes                      90 2

    Italy              Potatoes, tobacco             7
                       Vegetables                    7             0.5
                       Fruit                         14            0.5
                       Beets (incl. sugarbeet)       30            0.5

    Peru               Cotton, potatoes,
                       vegetables                    7

    Portugal           Pole beans                    4
                       Brassicas, lettuce            7
                       Apples, horse beans,
                       sugarbeet                     21
                       Wheat                         49
                                                                        

    Table 3.  (con't)
                                                                        

                                                     Preharvest
    Country            Crop                          Interval      MRL
                                                     (days)      (mg/kg)
                                                                        

    Spain              Cotton, fruit (incl.citrus),
                       maize, oilseeds,sugarcane,
                       tobacco, winter cereals       21
                       Potatoes, sugarbeet           21 or 28 3
                       Alfalfa                       28

    Sweden             Apples, beets, cereals,
                       currants, field beans,
                       oilseeds, peas, plums,
                       raspberries, vegetables       21

    Switzerland        Cereals                       28            0.02
                       Fodder beet                   42
                       Fruit                         21            0.2
                       Field beans                   42
                       Peas                          21
                       Sugarbeet                     42
                       Vegetables (excl.spinach)     14            1.0
                                                                        

    1  Spray application
    2  Granule application in furrow
    3  According to formulation

    APPRAISAL

         Ethiofencarb was evaluated by the 1977, 1978 and 1981 Joint
    Meetings. Additional information has been provided on residues in
    crops and on the fate of residues. Supervised trials were carried out
    on various crops at the recommended dosage rates.

         Residue levels on broad beans (green) were similar to those found
    in the previous experiments and did not exceed 0.04 mg/kg 11 to 14
    days after application. The residue in the pod ranged from 0.024 to
    0.11 mg/kg. The residue concentrations in Brussels sprouts, kale and
    lettuce were below 1.2 and 3 mg/kg respectively at intervals of 4 to 7
    days after application.

         Potato samples taken from 11 to 178 days after last treatment
    contained residues below 0.05 mg/kg in each case. The residues in
    cereal grains and green cereals grown after seed dressing were not
    detectable. In sugarbeet roots, residues did not exceed 0.05 mg/kg. 

    The residues in sugarbeet tops ranged from 2 mg/kg at day 25 to
    0.06 mg/kg at day 112.

         The residue in soil is partly taken up by rotational crops. The
    green part of pea and maize plants grown in a field treated with
    ethiofencarb 29 days preplanting contained maximum residues of 0.06
    and 0.23 mg/kg 61 and 75 days after sowing. The residues in peas and
    maize kernels were below and at or below the limit of determination
    (0.01 mg/kg) respectively. Ethiofencarb is rapidly converted to its
    sulphoxide and, at a slower rate, to its sulphone in plants.

         The total residue in the green part of the potato plants
    gradually decreased after foliar application, but reached the maximum
    7 days after drench application. The parent compound was non-
    detectable at day 7, while the ratio of sulphoxide to sulphone
    continually decreased.

         Organic solvents extract the majority (approximately 90%) of the
    total residue. The non-extractable radioactivity was found to be
    incorporated into the glucose derived from the hydrolysis of starch.

         The dissipation rate and the ratio of parent compound and its
    oxidative metabolites were similar in Chinese cabbage and potato. The
    degradation of ethiofencarb in soil is slower than in plants. The
    major portion of total residue is the sulphoxide derivative. The
    mobilities of the residues were found to be lower under field
    conditions than in laboratory model experiments.

         Ethiofencarb undergoes rapid degradation in water solution under
    UV light while the degradation rate is slower under a sunlight-
    simulating lamp. The ethiofencarb sulphoxide and 2-formylphenyl
    derivative were identified in the water solution.

    RECOMMENDATIONS

         In the light of the new information received, the Meeting
    reconsidered the results of supervised trials listed in the 1977 and
    1981 evaluations. On the basis of the whole set of data the following
    amendment is recommended:

                                                                        

    Commodity                  MRL       Preharvest interval on which
                               (mg/kg)   the recommendation is based
                                                    (days)
                                                                        
    Brassicas(except Chinese
    cabbage)                   2 1                      4

    Chinese cabbage            5                        4
                                                                        

    1  Revised from 5 mg/kg

    REFERENCES

    Bayer AG. Pflanzenschutzmittel-Rückstände (Pesticide Residues).
    1978-79   Brussels sprouts-Report Nos. 2047/78, 2049/78, 2006/79;
              Kale-Report No. 2004/79; Lettuce-Report Nos. 2050-2051/78;
              Oats-Report No. 2010/80; Potatoes-Report Nos. 2000-2001/79;
              Savoy cabbage-Report No. 2052/78; Wheat-Report Nos.2010/79,
              2041/79.(Unpublished)

    Bayer U.K. Ltd. Agrochemicals Division-Technical Reports TCR 142,
    1977-80   16.8.77; TCR 159, 15.3.78; TCR 182, 10.3.80. (Unpublished)

    Dräger, G. Untersuchung des Metabolismus von Croneton in Kartoffeln;
    1977      Versuche zur Identifizierung der nichtextrahierbaren
              Rückstände in Kartoffellaub.

    Bayer AG, Pflanzenschutz-Anwendungstechnik, Report RA-747.
         (Unpublished)

    Mobay Chemical Corp. Rotational crop residue experiment, Corn-Report
    undated   Nos. 67 187 - 67 189; Peas-Report Nos. 67 190 - 67 198.

    Takase, I. and Yoshimoto, Y. Metabolic fate of ethiofencarb
    1978      (O-ethylthiomethylphenyl methyl-carbamate) in Chinese
              cabbage. Nitokuno Report No. 1o85 (RA). (Unpublished)

    1979      Metabolic fate of ethiofencarb in potatoes and soil by
              foliar and drench applications, Nitokuno Report no. 1095
              (RA). (Unpublished)

    Wilmes, R. Orientierende Lichtstabilität. Bayer AG, Pflanzenschutz-
    1981      Anwendungstechnik. (Unpublished)





    See Also:
       Toxicological Abbreviations
       Ethiofencarb (ICSC)
       Ethiofencarb (Pesticide residues in food: 1977 evaluations)
       Ethiofencarb (Pesticide residues in food: 1978 evaluations)
       Ethiofencarb (Pesticide residues in food: 1980 evaluations)
       Ethiofencarb (Pesticide residues in food: 1981 evaluations)
       Ethiofencarb (Pesticide residues in food: 1983 evaluations)