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    PESTICIDE RESIDUES IN FOOD - 1979


    Sponsored jointly by FAO and WHO






    EVALUATIONS 1979





    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, 3-12 December 1979



    DICHLOFLUANID

    Explanation

    Dichlofluanid was evaluated at the meetings in 1969, 1974 and 1977.
    In 1977 when the temporary ADI was extended, further data were
    required on (1) studies to elucidate the accumulation seen in the
    thyroid and (2) results from current studies on the pathways of
    degradation, especially the fate of the fluorine-containing moiety of
    the molecule in or on plants.  In addition, further information
    concerning residues, especially residues on melons and leaf brassicas
    were considered to be desirable.

    At the 1979 Session of the CCPR, a number of questions were raised
    concerning the MRLs proposed for blackberries, gooseberries, eggplant
    and onions.

    The monograph addendum reviews the additional information received.

    EVALUATION FOR ACCEPTABLE DAILY INTAKE

    Biochemical Aspects

    Rats were dosed with 5 and 10 mg 14C-dichlofluanid/kg/body weight by
    oral and intravenous routes.  Forty to fifty percent of the dose was
    excreted in the urine within 8 hours after application.  The main
    radioactive metabolite in urine was identified as
    thiazolidin-2-thio-carbonic acid (TTC).  Eight hours after intravenous
    administration of 5 mg 14C-dichlofluanid/kg body weight, 74 to 92% of
    the urinary radioactivity was identified at TTC.  After oral
    administration, TTC was noted to range from 57 to 64% of the
    radioactivity in urine.  The remaining radioactivity was distributed
    among several other minor metabolites.  The parent compound was not
    identified in urine (Ecker, 1978).

    TOXICOLOGICAL STUDIES

    Signs of poisoning included apathy and dyspnea.  Sedation was observed
    in mice at high doses.  Post-mortem examination revealed pale and
    marble-like kidneys, pale and spotted liver, empty and reddish
    stomach, and intestine with erosion and decomposition of the gastric,
    glandular mucosa (Flucke, 1978).

    The acute oral LD50 for male rats of thiazolidin-2-thio-carbonic acid
    (TTC) the main urinary metabolite of dichlofluanid, is greater than
    1000 mg/kg body weight (Thyssen, 1978).

    Table 1.  Acute Toxicity of Dichlofuanid to Various Animals

                                                                      
                                           LD50
    Animal        Sex     Route         (mg/kg/b.w.)     Reference
                                                                      

    Rat           M       Oral          >5000            Flucke, 1978
    Rat           M&F     Oral          >5000            Flucke, 1978
    Mouse         M       Oral          5464             Flucke, 1978
    Mouse         F       Oral          5597             Flucke, 1978
    Guinea pig    F       Oral          945              Flucke, 1978
    Rabbit        F       oral          approx. 3500     Flucke, 1978
    Cat           F       Oral          >1000            Flucke, 1978
    Rat           M&F     Dermal (24
                          hr exposure)  >5000            Flucke, 1978
                                                                      

    Special Studies on Mutagenesis

    The Micronucleus test was carried out in male and female mice for
    possible mutagenic action on chromosomes of erythroblasts in bone
    marrow.  Two oral doses were given within 24 hours (2 × 1000 and 2 ×
    2000 mg dichlofluanid/kg/body weight).  Endoxan (cyclophosphamide) (2
    × 100 mg/kg body weight) was administered as positive control.  This
    test did not indicate any mutagenic action of dichlofluanid (Herbold,
    1978).

    An "Ames test" was performed to evaluate a possible point mutation
    activity of dichlofluanid.  Salmonella typhimurium TA-1535, TA 1537,
    TA-98 and TA100 strains were used in the tests at doses of 4, 20, 100,
    500 and 2500 µg/plate.  Endoxan (500 µg cyclophosphamid/plate) and
    trypoflavin (250 µg/plate) were used as positive controls.  An S-9
    microsomal activation system was used with all test doses.  A
    mutagenic effect of dichlofluanid was observed only with Salmonella
    typhimurium TA-100 at the 200 µg/plate dose.  Higher doses were
    toxic to the bacteria.  These experiments were repeated with the
    following test doses: 0, 50, 100, 200 and 400 µg/plate.  A mutagenic
    effect was observed in the 100 and 200 µg/plate doses with TA-100. 
    The 400 µg/plate dose was again toxic.  No mutagenic effects were
    observed with the TA-1535, TA 1537 or TA-98 strains.  Dichlofluanid
    was mutagenic in the "Ames test" only with the TA-100 strain (Herbold,
    1979a).

    Cytogenetic studies in the Chinese hamster spermatogonia were carried
    out with dichlofluanid given orally to male animals in two daily doses
    (2 × 250 and 2 × 500 mg/kg body weight).  The animals presented no
    clinical signs of poisoning, although one animal at the high dose
    died.  The positive control group received Adriblastin (doxorubicin) 2
    × 5 mg/kg body weight by intraperitoneal injection.  No differences
    were observed between the negative control and the
    dichlofluanid-treated animals.  Differences between the negative and
    positive control groups were highly significant (Herbold, 1979b).

    A dominant lethal study was carried out in mice.  Groups of 20 male
    (NMRI) mice received a single oral dose of 0 or 500 mg dichlofluanid
    per kg body weight.  After administration, each male was mated with 3
    untreated females, every week, for eight consecutive weeks.  The
    females were sacrificed on day 14 of gestation.  Pre-implantation and
    post-implantation losses were calculated from the number of corpora
    lutea, the number of implantations and the number of living and dead
    embryos.  Dichlofluanid treatment did not have any harmful effects on
    the males, did not impair their mating performance, and did not affect
    fertility.  Post-implantation data did not suggest any mutagenic
    action of dichlofluanid.  A significant pre-implantation loss was,
    however, observed in the second mating week (Machemer, 1974a).

    Special Studies on Embryotoxic and Teratogenic Effects

    Embryotoxicity and teratogenicity studies were carried out in rats
    following oral administration of dichlofluanid at daily doses of 0,
    30, 100 and 300 mg/kg body weight from day 6 to day 15 of gestation.
    On day 20, the foetuses were removed from the dams by Caesarian
    section and examined for visceral and skeletal malformations.  All
    test doses were slightly toxic to the dams.  Several animals showed
    acute poisoning signs (diarrhea, ruffled coat, dyspnea, inactivity,
    and loss of body weight).  There was no overt mortality in the study.
    This study revealed: (1) dichlofluanid was toxic by the oral route to
    pregnant dams at 30 mg/kg body weight/day and above; (2) a significant
    increase in the number of foetuses with malformations (P <0.05) was
    observed at the dose level of 100 mg/kg/day (the highest dose (300
    mg/kg/day) did not reveal an equivalent increase); and (3) a no effect
    level for foetal development was 100 mg/kg/day (Machemer, 1974b).

    Short-Term Studies

    The threshold dose of dichlofluanid was stated to be 5.4 mg/kg
    observed in a 10-month experiment reported to the meeting in abstract
    only (Belonozhkol, et al., 1978).  A review of the original data was
    not made and was considered to be necessary before the data can be
    fully evaluated.

    COMMENTS

    Dichlofluanid was evaluated for an acceptable daily intake by the
    meeting in 1969, 1974 and 1977.  A temporary ADI was established in
    1974 JMPR and extended at the same level in 1977.

    Several tests for mutagenicity (micronucleus, cytogenetic, dominant
    lethal, and microbial tests) were essentially negative.  However, a
    positive response was obtained in one bacterial strain in the "Ames
    assay".

    The studies required by the 1977 JMPR on the effects of the possible
    accumulation in the thyroid are known to be in progress.  The meeting
    extended the temporary ADI to allow these studies to be completed.

    TOXICOLOGICAL EVALUATION

    Level Causing No Toxicological Effect

    Rat:  1500 ppm in the diet, equivalent to 75 mg/kg body weight
    Dog:  1000 ppm in the diet, equivalent to 25 mg/kg body weight

    ESTIMATE OF TEMPORARY ACCEPTABLE DAILY INTAKE FOR MAN

    0 - 0.3 mg/kg body weight.

    RESIDUES IN FOOD AND THEIR EVALUATION

    USE PATTERN

    Pre-harvest treatment

    Information from the manufacturer (Bayer, 1979a) stated that they are
    not recommending the use of dichlofluanid on melons and leaf brassicas
    and therefore would not be supplying data for these crops.

    RESIDUES RESULTING FROM SUPERVISED TRIALS

    Information supplied by Bayer AG (Bayer, 1979a) reported that until
    1978 when a new ordinance was issued requiring the determination of
    the parent only, legislation in the Federal Republic of Germany had
    required the determination of the sum of dichlofluanid plus the
    metabolite dimethyl aminosulfanilide (DMSA).  Therefore, the great
    majority of their existing residue data was expressed as the combined
    residue with no possibility of differentiation between the two
    components.  As a result, the residues data compiled in the Table on
    pages 127 and 128 of the 1977 Evaluations and referring to Bayer
    Reports (coded country D) are invalid for reflecting the true residue
    situation and should be deleted, except for the potato results which
    were below detectable limits anyway.  The Nitokuno values in 1977 from
    Japan (coded country J) are correct and should be retained.  These
    include cucumber, eggplant, hops, lettuce, onion bulbs, strawberries
    under glass, and tomatoes.  In view of the widespread use of
    dichlofluanid and the large number of national MRLs already
    established (based mainly on parent compound alone), it is proposed to
    retain the other MRLs proposed in 1977 on a temporary basis and until
    such time as acceptable data from new field trials becomes available,
    including data supplied to this meeting.

    Additional residue data were received from supervised trials conducted
    in Japan and Finland and are summarized in Table 2.



        Table 2. Residues of dichlofluanid in fruits and vegetables from supervised trials

                                                                                                                                      
                                         Dose,           No. of          Days after         Residues               Reference
    Crop                 Country      kg a.i./ha      applications    last application       mg/kg
                                                                                                                                      

    Apple                Finland      0.004 kg/            3                 62             <0.005   peeled        State Inst. Agri.
                                      tree                                                  <0.005   washed        Chem., 1967
                                                                                            0.05     unwashed
                                                           4                 14             1.5      peeled
                                                                                            4.0      washed
                                                                                            3.2      unwashed
                         Finland      5 g/tree             1                 14             6.9      unwashed      State Inst.
                                                                                                                   Agri. Chem., 1973

    Black                Finland      3.75 g/bush          2                 56             0.5      unwashed      State Inst.
    currant                                                3                 38             1.0      unwashed      Agri. Chem., 1972
                         Finland      3.75 g/bush          2                 57             0.4      unwashed      State Inst.
                                                           3                 49             3.0      unwashed      Agri. Chem., 1973

    Cucumber             Japan        0.08g/m3             0                 - )
                                      (steam fog)          1                 1 )
                                                                             3 )
                                                                             7 )            all <0.006             Nitokuno, 1972
                                                           2                 1 )
                                                                             3 )
                                                                             7 )

    Cucumber             Japan        2                    0                 -              <0.003                 Nitokuno, 1973
    (greenhouse)                      (drench)             3                 3              0.007
                                                                             7              0.004
                                                                             14             0.005-0.007
                                                           5                 3              0.003-0.011
                                                                             7              0.005-0.009
                                                                             14             0.005-0.009
                                                                                                                                      

    Table 2.  Continued...

                                                                                                                                      
                                         Dose,           No. of          Days after         Residues               Reference
    Crop                 Country      kg a.i./ha      applications    last application       mg/kg
                                                                                                                                      

    Cucumber             Japan        0.08g/m3             0                 - )
    (greenhouse)                      (steam fog)          2                 1 )
                                                                             3 )
                                                                             7 )            All <0.01              Nitokuno, 19761
                                                           3                 1 )
                                                                             3 )
                                                                             7 )

    Cucumber             Japan        30                   0                 -              <0.01, 0.01            Nitokuno, 19761
                                      (drench)             1                 3              <0.01, 0.01
                                                                             7              0.14, 0.19
                                                           3                 3              0.04, 0.11
                                                                             7              0.03, 0.05

    Gooseberry           Finland      3.75 g/bush          2                 41             2.6      unwashed      State Inst. Agri.
                                                           3                 29             2.8      unwashed      Chem., 1972

    Hop                  Japan        31.25                2                 46             0.27                   Nitokuno, 1977
                                      (spray)              3                 37             0.28
                                                           3                 34-36          0.10

    Strawberry           Japan        0.04 g/m3            0                 -              <0.004, <0.004         Nitokuno, 19731
    (greenhouse)                      steam fog)           1                 1              0.023, 0.021
                                                                             3              0.012, 0.010
                                                                             7              0.006, 0.012
                                                           2                 1              0.040, 0.020
                                                                             3              0.011, 0.014
                                                                             7              0.008, 0.010
                                                                                                                                      

    Table 2.  Continued...

                                                                                                                                      
                                         Dose,           No. of          Days after         Residues               Reference
    Crop                 Country      kg a.i./ha      applications    last application       mg/kg
                                                                                                                                      

    Strawberry           Japan        24.9                 0                 -              <0.01, <0.005          Nitokuno, 1975
                                      (drench)             6                 1              0.24, 0.166
                                      plus                                   3              0.10, 0.246
                                      2                                      7              0.06, 0.082
                                      spray                8                 1              0.12, 0.178
                                                                             3              0.08, 0.278
                                                                             7              0.03, 0.071

    Strawberry           Japan        24.9                 0                 -              <0.01, 0.006           Nitokuno,19751
    (greenhouse)                      (drench)             6                 1              0.27, 0.292
                                      plus                                   4              0.08, 0.114
                                      7                                      7              0.18, 0.234
                                      (spray)              8                 1              0.10, 0.266
                                                                             4              0.10, 0.146
                                                                             7              0.20, 0.409

    Strawberry           Finland      0.25 kg/             3                 19             0.2      washed        State Inst. Agri.
                                      line meter                                            0.6      unwashed      Chem., 1967
                                      11 g/a               3                 19             0.15     washed
                                                                                            0.5      unwashed
                                      0.25 kg/             2                 26             0.02     washed
                                      line meter                                            0.4      unwashed
                                      11 g/a               2                 26             0.01     washed
                                                                                            0.01     unwashed
                         Finland      0.25 kg/             3                 14             0.03     washed        State Inst. Agri.
                                      line meter                                            0.07     unwashed      Chem., 1968
                                                           2                 26             0.03     washed
                                                                                            <0.03    unwashed
                         Finland      25 g/a               3                 8              18       unwashed      State Inst. Agri.
                                                           2                 15             1.5      unwashed      Chem., 1971
                                                                                                                                      

    Table 2.  Continued...

                                                                                                                                      
                                         Dose,           No. of          Days after         Residues               Reference
    Crop                 Country      kg a.i./ha      applications    last application       mg/kg
                                                                                                                                      

    Tomato               Japan        0.08 g/m3            0                 -              <0.004                 Nitokuno, 1972
    (greenhouse)                      (steam fog)          1                 1              0.005
                                                                             3              <0.004
                                                                             7              <0.004
                                                           2                 1              0.014
                                                                             3              <0.004
                                                                             7              <0.004
                         Japan        0.08 g/m3            0                 -              <0.01, <0.01           Nitokuno, 19761
                                      steam fog            2                 1              0.02, <0.01
                                                                             3              <0.01, <0.01
                                                                             7              <0.01, <0.01
                                                           3                 1              <0.01, <0.01
                                                                             3              0.01, <0.01
                                                                             7              <0.01, <0.01

    Watermelon           Japan        30                   0                 -              <0.01, <0.01           Nitokuno, 19761
                                      (drench)             5                 7              <0.01, <0.01
                                                           6                 7              <0.01, <0.01
                                                                                                                                      

    1  Samples analysed by two different institutes.
    


    FATE OF RESIDUES

    In plants

    Dichlofluanid labelled with 14C in the dichlorofluoromethyl position
    was sprayed on wine grapes 35 days before harvest time (Voleler et
    al., 1979).  At harvest only 29% of the applied radioactivity could
    be detected while 71% had vaporised.  Of the remaining radioactivity
    in the grapes, 91% was in the form of unchanged starting material.  A
    methanol extract of the grapes contained small quantities (2.2% and
    5.3%) of two unidentified metabolites.  During wine making, 23% of the
    radioactivity in the grapes went over into the wine, 70% remained in
    the residue (must), and 6% was evolved with the CO2 given off.  Of
    the radioactivity in the wine, 70-80% was identified at the metabolite
    thiazolidine-2-thione-4-carboxylic acid (TTCA) arising from the
    reaction between thiophosgene and cystein.  The content of TTCA in
    wine was around 0.1 mg/l.

    The degradation and metabolism of 14C-dichlofluanid
    (dichlorofluoromethyl position labelled) in strawberries was studied
    by Westphal, et al. (Westphall et al, 1979).  Strawberry plants
    grown in a closed, air flow controlled glass cultivating system were
    sprayed with an aqueous preparation of the 14C-50% wettable powder at
    the end of the flowering period and cultivated in the closed system
    until harvest (36 days).  Strawberries, leaves, roots and soil
    contained 8%, 71%, 3% and 5% respectively, of the originally-applied
    radioactivity, while 6% 14C-CO2 was released along with traced of
    carbonyl sulphide.  Small amounts of radioactivity were found in the
    condensed and percolated water of the system.  Results are tabulated
    as follows:



        Table 3.  Distribution of 14C-dichlofluanid metabolites in strawberry culture system

                                                                                                   

                                   Extractable radioactivity, %
                                                                               
                                                   Less polar        Polar               bound
                      Dichlofluanid     TTCA      metabolite (5)   metabolite (5)    radioactivity
                                                                                                   

    Strawberries           -            1.3           6.3             37.3               55.1
    leaves                38.6          7.0            -              24.6               29.8
    soil                   -             -            2.7             12.3               85.0
    (upper 5 cm)
                                                                                                   
    


    From this experiment, it is concluded that the
    dichlorofluororomethylmercapto moiety of the parent compound is easily
    cleaved off, leading to unstable intermediates such as sulfinic acid
    and thiphosgene or its fluoro analogue.  This mechanism is supported
    by the detection and identification of carbonyl sulphide, a hydrolysis
    product of thiophosgene and TTCA, a reaction product of thiophosgene
    and naturally-occurring cysteine.  Eventually the chlorine and
    fluorine atoms are released as inorganic ions.  Similar results and
    conclusions were obtained for an experiment using 14C-tolylfluanid
    although more undegraded parent compound was found in strawberries in
    this case (Haque, et al., 1979).  The metabolic pathway for either
    dichlofluanid or tolylfluanid is shown in Figure 1.

    The metabolism of the tolyl analogue of dichlofluanid, tolylfluanid,
    was determined on apples growing on small trees growing in a
    greenhouse (Vonk, et al., 1977).  After 28 days post-treatment,
    approximately 42% of the originally applied-radioactivity (as
    dichlorofluoromethyl-14C, tolylfluanid spray) had disappeared
    probably as volatile compounds, ca. 41% was due to unchanged starting
    material, and ca. 17% was unidentified material.

    In soil

    Information on the rate and extent of the degradation of
    14C-dichlofluanid (labelled in the dichlofluoromethylthio carbon) in
    soil was provided in a report on an experiment utilizing two soil
    types, a high humus sandy loam (soil I) and a medium humus sandy loam
    (soil II), incubated in biometric flasks fitted with side-arm chambers
    containing 0.1 N KOH (Schuphan, et al., 1979a).  The results are
    summarised in Table 4.

    Similar results were obtained for 14C-tolylfluanid (Schuphan, et
    al., 1979b).  Additional information on soil degradation was provided
    in Table 2.

    Table 4. Degradation of 14C-dichlofluanid in soils

                                                                       

       Time after           Total 14CO2          Extractable 14C-
        start of             evolved, %               remaining, %
    experiment, days     soil I      Soil II        Soil I      Soil II
                                                                       
            3             45.0        36.4           4.7         57.0
            7             61.5        57.2           1.3         (5.3)
           14             69.5        77.1           0.92        20.4
           31             74.0        92.7           0.52         1.7
           63             77.5        98.5           0.36         0.80
                                                                       

    FIGURE 1

    In storage and processing

    Strawberries treated in a normal way with non-radioactive
    dichlofluanid to yield an analytically determined residue of 5.9 mg/kg
    parent compound (I) and 1.6 mg/kg of the metabolite
    dimethylaminosulfanilid (II) when harvested two days after treatment,
    were subjected to various processing steps to give unwashed raw
    berries, washed raw berries, canned fruits, pasteurized juice, and jam
    which were analysed to evaluate the effect on residues (Hartman, et
    al., 1979).  Substantial reductions in residues were achieved by
    processing as shown in Table 5.

    Table 5. Concentration of active ingredient and metabolite on
    strawberries and processed products.

                                                         
    Sample                     I, mg/kg        II, mg/kg
                                                         

    Berries, unwashed          5.9             1.6
    Berries, washed            0.35            0.85
    Wash water                 1.95            0.2
    Juice, raw                 0.02            0.85
    Juice, pasteurized         N.D.1         0.9
    Pomace                     0.35            1.4
    Canned fruits              0.02            0.75
    Jam                        N.D. 1        0.4
                                                         

    1  N.D. = not detectable.


    Photodecomposition

    In studies carried out in England, the degradation of dichlofluanid by
    ultraviolet light was measured in methanol, benzene, and acetone
    solution (Clark et al., 1978).  Solutions in methanol or benzene
    deposited a brown solid on the UV lamp surface (Hanovia, 100 W.)
    stopping the reaction.  In acetone solution darkening occurred, but no
    solid separated, permitting a reaction time of one hour.  Products
    from the acetone solution included N,N-dimethyl-N'-phenylsulfamide,
    phenyl isocyante, phenyl isothiocyanate, and dimethylamidosulfonyl
    chloride.  The presence of bis (dichlorofluoromethyl) disulfide,
    1-(dichlorofluoromethylthio) propan-2-one and
    1-(dichlorofluoromethyl-sulfonyl) propan-2-one.  In vivo tests
    against Botrytis einerea showed that irradiation decreased the
    activity of dichlofluanid and that synergism did not occur.


    EVIDENCE OF RESIDUES IN FOOD IN COMMERCE OR AT CONSUMPTION

    Information was supplied by Sweden on the results of analysing twenty
    samples of Swedish strawberries during 1979.  No samples contained
    detectable levels of dichlofluanid (<0.03 mg/kg, Sweden, 1979).  The
    results of monitoring surveys on several lots of produce imported into
    Finland during 1978 are shown in Table 6 (Finland, 1979).

    Table 6. Occurrence of residues of dichlofluanid in produce imported
    into Finland in 1978

                                                                
    Commodity         No. of positive results    Found (mg/kg)
                                                                

    Cucumbers                   6                0.01-0.28
    Apples                      1                0.06
    Strawberries                2                <0.01, 0.11
    Sweet peppers               1                0.10
                                                                

    Finland also supplied information on levels of dichlofluanid found in
    Finnish strawberries over the period 1975-1978.

    Table 7. Occurrence of residues in strawberries grown in Finland

                                                                     
                                    Number of samples containing
    Year       Number of samples    dichlofluanid levels within
               analysed             given range, mg/kg
                                                                
                                    <0.1      0.11-1.0   1.1-2.0
                                                                     

    1975              98              34           7         -
    1976              138             50          14         -
    1977              139             48          20         -
    1978              119             34          13         2
                                                                     

    There was no explanation for the discrepancies in samples numbers.

    METHODS OF RESIDUE ANALYSIS

    The method of analysis in Sweden (1979) was reported to be that of
    Johansson (1978).  Finland reported using a method of Johansson (1974)
    and Becker (1971).

    NATIONAL MRLs REPORTED TO THE MEETING

    The Swedish maximum acceptable level for dichlofluanid is 5 mg/kg for
    fruits and vegetables except potatoes. Sweden (1979).

    APPRAISAL

    Data supplied in 1977 from residue trials in Germany (F.R.) were based
    on legislation requiring analysis for total residues of dichlofluanid
    and metabolite which has since been changed, invalidating that data
    source.  However, new data were received in 1979 from Japan and
    Finland which support the 1974 and 1977 recommendations for MRLs for
    apples, cucumbers, gooseberries, hops, strawberries and tomatoes.
    Sufficient information on national limits for blackberries, eggplants,
    peppers cereal grains and wheat straw was available to make it
    possible to retain the 1977 MRLs on a temporary basis until such time
    as valid data from supervised trials becomes available.

    Extensive information was received on the pathways of degradation and
    metabolism of dichlofluanid, including the fate of the
    fluorine-containing moiety of the molecule in plants (especially
    strawberries) and soil, satisfying the requirements of the 1977 Joint
    Meeting.  Dichlofluanid is degraded fairly rapidly as the
    dichlofluoromethylmercapto group is easily cleaved off, leading to
    unstable intermediates and ultimately to
    thiazolidine-2-thione-4-carboxylic acid (TTCA), a reaction product of
    thiophosgene and cysteine.  Soil residues degraded to CO2 and
    extractable products rapidly and extensively.  After 63 days, 98.5% of
    applied radioactivity had evolved as 14C-CO2, while only 0.80%
    remained as extractable products.

    Data were received on the effects of processing on residues in
    strawberries.  Washing reduced dichlofluanid residue from 5.9 mg/kg to
    0.35 mg/kg.  Further processing into pasteurized juice, canned fruits
    and jam reduced the residue to not detectable, 0.02 mg/kg, and not
    detectable respectively.

    The manufacturer of dichlofluanid has indicated that it is not
    recommending uses on leafy brassicas, negating the need for further
    residue data on this crop.

    RECOMMENDATIONS

    The temporary maximum residue limits recommended in 1977 for
    blackberries, eggplants, sweet peppers, cereal grain and wheat straw
    are retained on a temporary basis until data indicating the level of
    residues of the parent compound become available.  The limits for all
    present and past recommendations refer to dichlofluanid only.

                           Temporary maximum residue
      Commodity                  Limit, mg/kg

    Blackberries                      15
    Sweet peppers                     2
    Eggplants                         1
    Cereal grains                     0.1
    Wheat straw                       0.5

    FURTHER WORK OR INFORMATION

    Required by 1982

    1.  Residue data for dichlofluanid only, from supervised trials on
    blackberries, eggplants, peppers, cereal grains and wheat straw.

    2.  Studies to elucidate the accumulation seen in the thyroid.

    REFERENCES

    Becker, G.  Gaschromatographische Simultan-Bestimmung von chlorierten
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    See Also:
       Toxicological Abbreviations
       Dichlofluanid (FAO/PL:1969/M/17/1)
       Dichlofluanid (WHO Pesticide Residues Series 4)
       Dichlofluanid (Pesticide residues in food: 1977 evaluations)
       Dichlofluanid (Pesticide residues in food: 1981 evaluations)
       Dichlofluanid (Pesticide residues in food: 1982 evaluations)
       Dichlofluanid (Pesticide residues in food: 1983 evaluations)