DICLORAN      JMPR 1977


    Dicloran was evaluated by the Joint Meeting in 1974 (FAO/WHO, 1975). A
    temporary acceptable daily intake for man was estimated to be 0.03
    mg/kg body weight and recommendations were made for temporary maximum
    residue limits in a range of fruits and vegetables.

    The Meeting considered that further studies on the ocular disturbance
    observed in dogs to confirm and clarify this effect and further
    information on the fate in livestock (since plant material containing
    residues may be fed to animals) were required before the temporary ADI
    and recommended maximum residue limits could be confirmed. The Meeting
    also considered that it was desirable to have information on the
    following points.

    1. Effects on hepatic microsome systems in several species.

    2. Further observations in humans.

    3. Further information on the fate of residues during storage,
       transport and processing of fruit and vegetables.

    4. Information on transfer of residues from grapes to wine and on
       possible influence on wine processing.

    5. Further information on soil residues and their possible uptake into
       subsequent crops.

    6. Further data to clarify inconsistencies in the residue levels found
       in different berries.

    The Codex Committee on Pesticide Residues at its 9th Session (1977)
    considered a request to increase the maximum residue limits for
    dicloran on apricots to 15 mg/kg and to include a similar
    recommendation for nectarines.

    Information on some of these matters together with information about
    the nature and level of dicloran residues on various crops was
    available for evaluation by the Meeting and is summarized in the
    following monograph.

    Attention is drawn to a number of errors which appear in the 1974
    monograph (FAO/WHO, 1975.)

    Page 215 "DinitranilR" is not a registered trade mark for
    dicloran. "RegisanR" is another trade mark for dicloran. Solubility
    in glacial acetic acid is 0.8 g, not 8.8 g/100 ml.

    Page 216 The technical material typically contains not less than
    96% dicloran.

    Page 225 Use pattern -- dicloran is registered and sold in the
    following countries -- Australia, Brazil, Canada, Egypt, Greece,
    Holland, Israel, Italy, Japan, New Zealand, South Africa, UK, USA,

    Third paragraph -- delete "thiram (TMTD)" and insert "captan".

    Page 235 Page 235 should appear between page 237 and 238.



    Absorption, distribution and excretion

    Prolonged oral administration of dicloran to dogs (25 and 50
    mg/kg/day) produces lesions in the cornea and lens of the eye, but
    this occurs only in the light (Curtis et al., 1968; Bernstein et al.,
    1970; Earl et al., 1971). Comparable studies in miniature swine (Earl
    et al., 1971) and in human volunteers (0.4 mg/kg/day) for 3 months
    (Upjohn, 1962) produced no similar ocular symptoms. Toxicity studies
    carried out on rats and Rhesus monkeys show that the oculotoxicity is
    confined to the dog (Serrone et al., 1967).

    14C-dicloran (100 mg/kg/day for 5 days) was administered orally to
    dogs (4), pigs (4) and rats (8). The radiolabelled residues in dog and
    pig tissues were similar and higher than in the rat. All 3 species
    showed a high residue in the liver but in dogs and pigs the highest
    residues were found in the pigmented tissues of the eye. Nonpigmented
    eye tissues (cornea and lens) had low residues and there was no
    correlation between oculotoxicity and tissue residues of dicloran and
    its metabolites. A more rapid increase of plasma levels of 14C occurs
    in the dog. At 3 days of dosing the plateau plasma levels in pig and
    dog were similar (10-15 mg/kg 24 hours after dosing).

    The levels of radioactivity excreted in the bile of dogs and pigs were
    high. The spectrum of metabolites, on preliminary examination, shows
    significant species differences (Hamilton, 1977).


    10-40 mg/kg of dicloran was administered orally or interperitoneally
    to rats. Following i.p. injection 83% of the dose was excreted in the
    urine in 3 days (70% in 24 hrs) and 1.5% was excreted in the faeces;
    after oral administration 91% of the dose was excreted in the urine in
    3 days (77% in 24 hrs) and 1% was excreted in the faeces. Little
    appears to be excreted in the bile of the rat (2% of the dose in 6 hrs
    after i.p., 5% in 12 hrs after oral).

    The major metabolite present in the urine was
    4-amino-3,5-dichlorophenol (50% of the dose, 70% of the urinary
    activity) and the only other metabolite detected in the urine was
    4-amino-2,6-dichloroaniline (Matè et al., 1967).

    In vitro studies with mouse-liver microsomes gave equal and small
    amounts each of 4-amino-3,5-dichlorophenol (aminophenol) and
    4-amino-2,6-dichloroaniline (phenylenediamine).

    Similar routes of metabolism have been found in rats, dogs and monkeys
    (Bachmann et al., 1971).

    Dicloran stimulated rat liver mixed function oxidases at oral doses of
    10 mg/kg or more; doses of 500 mg/kg, decreased mitochondrial
    oxidation of succinate without concomitant uncoupling of oxidative
    phosphorylation (Bachmann et al., 1971). In single dose experiments,
    oxidative phosphorylation was not affected at any dose level. Dicloran
    does not affect brain or liver mitochondrial function of mice.

    Daily administration of 1000 mg/kg to rats produced uncoupling of
    oxidative phosphorylation after 4 days. The metabolite of dicloran,
    4-amino-3,5-dichlorophenol was as active as 2,4-dinitrophenol, in
    vitro, in uncoupling oxidative phosphorylation, whereas dicloran was
    only one-tenth as effective. The phenylenediamine metabolite had no
    effect in vitro on mitochondrial respiration or oxidative
    phosphorylation (Bachmann et al., 1971).

    It should be remembered that the metabolite 4-amino-3,5-dichlorophenol
    is excreted in the urine of rats as a conjugate (Matè et al., 1967)
    and conjugation of this metabolite in the liver would lead rapidly to
    its deactivation in vivo.

    Dicloran and its metabolite, 3,5-dichloro-4-aminophenol, inhibited
    electron transport and uncoupled oxidative phosphorylation at 10-5M
    in vitro, whereas the metabolite 2,6-dichlorophenylenediamine showed
    only slight uncoupling at 10-4M. These inhibitory effects in vitro
    cannot be considered as serious adverse effects since they are not
    confirmed by similar observations in vivo. Mitochondria isolated
    from rats treated with dicloran or its metabolites were functionally
    normal (Gallo at al., 1976).


    Special study on mutagenicity

    Dicloran was shown not to be a mutagen in strains of
    B.subtilis, S. typhimurium and E.coli (Shirasu at al., 1976).
    These studies did not include metabolic activation of the test
    chemical (dicloran) with rat liver microsomal preparations.

    Special study on carcinogenicity

    One study describes dicloran as non-toxic and non-carcinogenic. The
    number of animals on test at the higher dose level (about 500
    mg/kg/day, for 1 year) was only 5. The number on test at the lower
    level (29 animals at about 150 mg/kg) was sufficient to detect a very
    low order of carcinogenicity (Hadidian at al., 1968).

    An LD50 in the rat of 1500-4040 mg/kg is reported by Jones et al.
    (1968) and Backmann et al. (1971).

    Short term studies


    The experiments are summarised as follows:

    500 mg/kg/day for 4 days; 500 mg/kg/day for 30 days; 500 mg/kg/day for
    12 weeks; 1000 mg/kg/day for 4 days; (Gallo et al., 1976).

    Doses of 400 mg/kg/day to rats for 3 months were without apparent
    serious adverse effects, but is not noted that at 1000 mg/kg/day there
    were some deaths (Serrone et al., 1967).


    It has been reported that oral doses of 160 mg/kg/day were lethal to
    monkeys within 3 months, and that these dosages were more toxic to the
    male animals than to the females. It was observed further that the
    urine of rats receiving dicloram chronically was orange-coloured, but
    that the samples obtained from monkeys were not (Serrone et al.,

    Long term studies


    In an experiment, rats were dosed according to the regimen: oral
    administration 5 days/week for a total of 260 doses. Dicloran was
    given at 3 dose levels: 30, 100 and 300 mg/rat/day. The last of these
    dosages killed 2/3 animals, while at 100 mg/rat/day the mortality was
    0/3 males and 1/3 females. At the 30 mg/rat/day level the mortality
    was 0/14 males and 0/15 females. (Average survival times are given as
    556 days for the males and 563 days for the females at 100 mg/rat/day;
    497 and 499 days, respectively, for the males and females at 30
    mg/rat/day. Since the initial weights of the 100 mg/rat/day males
    averaged 57 g and the final weights averaged 369 g (for the females,
    55  "illegible") the 100 mg/rat/day regimen provided an average
    intake of about 500 mg/kg/day for the males, and of about 550
    mg/kg/day for the females. Similarly, the 30 mg/animal/day regimen

    provided mean intakes of about 140 mg/kg/day for the males and of 175
    mg/kg/day for the females (Hadidian et al., 1968).

    Rat and monkey

    Dicloran administered orally to rats (400 mg/kg/day) produced
    significant liver enlargement and increased the activities of the
    liver microsomal enzymes (demethylase and desulphurase) after either
    single or multiple administrations; liver mitochondrial utilization of
    O2 was simultaneously increased. No changes in heart or kidney
    mitochondrial oxygen consumption was observed. No enhancement of the
    hepatic microsomal enzymes occurred in monkey. Centrilobular fatty
    infiltration of liver, and mitochondrial swelling and distortion of
    the cristae were observed in liver and kidney, in the monkey (Serrone
    et al., 1967).


    Dicloran (2,6-dichloro-4-nitroaniline) was previously evaluated and a
    temporary ADI for humans was established. Further studies on the
    oculotoxicity observed in the dog and of the fate of dicloran in
    livestock were requested. Further work on the effects of dicloran on
    the hepatic microsomal enzymes of animal species and further
    observations of the effects of dicloran in humans were considered

    A study of the disposition of orally administered 14C-dicloran in
    rats, dogs and pigs has shown substantially higher concentrations of
    radioactivity in the tissues of dog and pig than rat. A more rapid
    increase in plasma concentration of 14C in the dog than in either pig
    or rat, and a different spectrum of the metabolites suggests that
    there is a species differences in the kinetics of metabolism. The
    higher concentration of 14C in the retina and iris of the eye of the
    dog than occurs in other dog tissues or in the pigmented tissues of
    the eye of the rat or pig, goes some way to explaining the
    photosensitive oculotoxic effects of dicloran which have been observed
    in the dog. It is likely that at least some of this radioactivity
    present in the pigmented tissues of the dog eye is attributable to the
    major metabolite of dicloran, 4-amino-3,5-dichlorophenol; under the
    influence of light this would be oxidized to the corresponding
    quinoneimine which could diffuse into the non-pigmented tissues of the
    eye, the lens and cornea, producing lesions owing to the oxidation of
    this metabolite.

    The oculotoxic effects in the dog are therefore partly explained by
    the different kinetics of dicloran seen in this species and the known
    sensitivity of the dog eye to oxidant chemicals. No similar oculotoxic
    effects have been seen in rat, pig, Rhesus monkeys or humans dosed
    with dicloran.

    Dicloran, at doses of 10 mg/kg/day or more, results in induction of
    the microsomal mixed function oxidases of rat liver, larger doses (400
    mg/kg/day) result in liver enlargement, and still larger doses (500
    mg/kg/day) decreased mitochondrial oxidation, but without the
    uncoupling of oxidative phosphorylation. Both dicloran and its major
    metabolite, 4-amino-3,5-dichlorophenol, inhibit mitochondrial electron
    transport and uncouple oxidative phosphorylation in vitro but not
    in vivo, probably because of the conjugation of the metabolite(s)
    in vivo.

    In mutagenicity studies in various strains of B.subtilis and
    S.typhimurium and E.coli, with and without activation by rat liver
    microsomal enzymes, dicloran was not found to be mutagenic.

    In view of the further work carried out to explain the oculotoxicity
    of dicloran in the dog, the metabolic and pharmacokinetic studies in
    the pig, and studies on the effects of dicloran on liver microsomal
    enzymes, in compliance with the requests of the Joint Meeting, 1974,
    it was recommended that the previous temporary ADI for humans be made
    an ADI for humans at the same level.


    Level causing no toxicological effect

        Rat: 1000 mg/kg in diet, equivalent to 50 mg/kg bw

        Dog: 10 mg/kg in diet, equivalent to 2.5 mg/kg bw


        0-0.03 mg/kg/bw



    In addition to the uses summarized in 1974 (FAO/WHO 1975) dicloran is
    recommended and registered for pre-harvest treatment of beans,
    cucumbers, endives, gherkins, lettuce, melons, parrika and wetloof
    chicory, mostly for the control of Botrytis and Sclerotinia.
    Attention is drawn to the fact that dicloran is a fungistat rather
    than a fungicide. It is fungistatic to the mycelium and spores of
    Botrytis cinerea. It delays germination and causes a severe check to
    hyphal growth. It is suggested that dicloran is a structurally
    non-specific toxicant exerting its effect by disorganizing cell growth
    and division in particular plant pathogens.

    To exert its effect and to maintain treated fruit and vegetables in a
    disease-free condition there must be a biologically effective
    concentration of dicloran evenly distributed over the surface of
    commodities susceptible to attack by these rot-producing



    No new information was available to enable the Meeting to judge the
    necessity to raise the maximum residue limit from 10 mg/kg to the
    proposed level of 15 mg/kg. The data from extensive residue studies in
    California in 1964 which were evaluated by the 1974 Meeting were
    re-examined. It was judged that the summary in the 1974 monograph
    (FAO/WHO 1975) reflects the findings in these trials.  It is
    recognized that a number of countries have established maximum residue
    limits higher than 10 mg/kg for apricots to reflect the residues
    resulting from both pre-harvest and post-harvest use and it is noted
    that the data on which these limits were established will be furnished
    to a future Joint Meeting.

    Berry fruit

    No additional information has become available to throw light on the
    matter of the wide variation in residue levels reported in trials
    evaluated in 1974. However, the raw data from these trials have been
    examined and there appear to be no anomalies in the conduct of the
    trials or in the analysis of samples.

    There were several species of berries involved and a number of
    different cultivars of separate species. Although the trials were
    mostly conducted in the northwest of the USA, the ecological and
    environmental conditions were obviously different at the different
    trial sites. All the data show a distinct trend for the highest
    residue levels to be found following the application of the highest
    rate of dicloran and for the residues to be higher when the interval
    between last treatment and harvest is shortest.

    Since the analyses were all carried out in the same laboratory by the
    same methods of analysis, it must be concluded that the variation that
    was found is typical of that occurring with berry fruits under
    practical conditions. No doubt the surface structure of the berries
    affects the retention of the spray. Whether minor variations in
    spraying, technique or spray equipment contribute to the variation
    cannot be determined from the information available, but this seems
    highly probable.

        TABLE 1. Dicloran residues resulting from supervised trials
                                        Application             Residues (mg/kg) at intervals (days) after application

    Crop        Country         Year    no.   rate         formulation    0       1      3      7       14     21        27
                                              kg a.i./ha
    Gherkin     Netherlands,    1970    1     0.7          smoke          0.4            0.2    <0.2
                                1972          0.7          "                     0.6     0.1

    Lettuce     Netherlands     1970    1     0.7                         5.1                                  < 0.3     < 0.3
                                        2     0.7                                                       0.3
                                1970    1     1.4                                                                        < 0.3
                                1970    2     1.4                                                       0.3
                                1970    1     2.8                                                       2.2
                                1970    2     0.7                                                       3.9    5.0       2.9
                                1970    2     0.7                                                       4.6    4.8       4.6
                                1970    2     0.7                                                       2.6              0.7
                                1973    3     0.7 + 6.4    smoke
                                                           generator      20.3                  2.2     0.7    0.2
                                1973    3     "                           12.0                  3.8     2.0    0.9
                                1973    3     "                                                 5.6     3.1    1.8
                                1973    3     "                           8.3                   3.1     1.0    0.7


    Studies in the Netherlands where dicloran was applied by means of a smoke generator to gherkins growing in glasshouses showed that, generally,
    the residue deposited on the fruit is less than 1 mg/kg immediately after treatment. The residue level declines rapidly and thus the fruit, which
    must be harvested continuously, is unlikely to contain more than 1 mg/kg of dicloran residues. See Table 1.


    Extensive studies in the Netherlands in 1970-73 showed that when lettuce in glasshouses is treated with dicloran applied by means of a smoke
    generator the residue levels vary greatly irrespective of the amount applied. The rate of decline of residues is relatively slow, being
    influenced by the confined environment of the glasshouse. A combination of soil treatment and treatment by means of smoke generator produces
    higher residues which decline at least as rapidly as those deposited by the smoke generators alone.


    The use of dicloran in the production of chicory (Wetloof) in forcing beds has been practiced since 1961. Trials carried out in the Netherlands
    have shown that the spray application of dicloran as dust or wettable powders at rates up to 20 mg/kg on the roots and forcing beds produces
    residues ranging from 1-35 mg/kg on the roots but only up to 0.5 mg/kg on the edible portion, the sprouts. Likewise the dripping of chicory roots
    prior to planting leads to dicloran residues of up to 35 mg/kg in the roots but less than 0.5 mg/kg in the sprouts. Significant residues occur in
    waste products used for animal feed.


    Dicloran has proved effective for controlling storage rots of onions, especially those caused by Botrytis alii and Sclerotinia cepivorum, when
    applied as a dust (8%) to the onions in storage bins. The dust is used at the rate of 1 kg/tonne of onions. Studies in Australia (Allen, 1973)
    showed that the residue level is directly related to the rate of application. The bulk of the dicloran is confined to the outer layers,
    especially to the loose paper-like layers surrounding the bulb. It was observed that the process of sorting and packaging, which incidentally
    results in dislodging much of the outer paper-like layer, reduces the residue to approximately half. The results of these studies are summarised
    in Table 2.

    TABLE 2. Dicloran residues on onions treated post-harvest


                                        Residue level mg/kg
    Rate of application      Inner layer    Outer layer    Whole bulb

    1 kg 8% dust/tonne          1.09           21.63          10.20

    2 kg 8% dust/tonne          1.32           47.6           21.00

    dust-after sorting
    and packaging               1.14           20.90          9.56

    Nectarines, peaches

    Allen et al. (1973) carried out a trial to determine the effect of a
    new colloidal formulation of dicloran on residue levels on peaches and
    nectarines dipped in suspensions containing 0.065% and 0.075%
    dicloran. Residues were determined at 1, 2, 4, 6, 8, 10, 12 and 14
    days after dipping. The residue level varied from 3 to 12 mg/kg in the

    case of peaches and 2 to 6 mg/kg for nectarines. Obviously the nature
    and condition of the skin of the fruit affects the uptake and
    retention of dicloran. There was considerable variation between
    samples analysed on various days with no consistent trend; in fact the
    highest residue was found on the samples taken 14 days after dipping.
    These data support the recommendation made in 1974 for peaches and
    suggest that nectarines are similar to apricots in their capacity to
    take up and retain dicloran residues. See also "Fate of residues", "In


    In animals

    Hamilton (1977) has reported the results of a study designed to
    determine the distribution of dicloran in the tissues of rats, dogs
    and pigs following repeated oral dosing at 100 mg/kg/day. For further
    details of this and other metabolic studies see "Biotransformation".

    Pigs slaughtered 24 hours after the administration of the last of 5
    daily doses of dicloran equivalent to 100 mg/kg were found to have
    varying levels of radioactivity in many different tissues ranging from
    1 mg/kg dicloran equivalent in brain through 2 mg/kg in muscle, 8
    mg/kg in fat and kidney to 24 mg/kg in liver, with somewhat higher
    levels in sections of the eye. The experiment was not designed to
    determine the rate of build-up or rate of excretion of dicloran
    following consumption by pigs.

    Wright (1968) reported that the administration to dairy cows of high
    levels of dicloran (50 mg/kg/day) resulted in easily detectable milk
    residues which persisted for up to 7 days following treatment. The
    maximum level detected in milk following 2 to 3 days of administration
    was 7 mg/kg. This however was in a cow whose milk production dropped
    to one-quarter to that observed prior to beginning treatment. The
    highest concentration detected in the milk of other cows in the trial
    was 0.2 mg/kg. The concentration of dicloran residues in the milk 24
    to 36 hours after discontinuing administration was only of the order
    of 0.05 mg/kg. The limit of determination of the method used (GLC) was
    0.01 mg/kg.

    In a parallel trial Wright (1968) administered dicloran in the rations
    of dairy cows at levels of 0, 5, 20 and 80 ppm in the total diet,
    daily for 28 days. The residue picture of the milk from all 9 cows
    receiving dicloran was not significantly different from that of
    control cows receiving unmedicated rations. In view of the level of
    residues found in agricultural commodities following the use of
    dicloran as a fungistat, these results provide assurance that residues
    are not likely to occur in milk following the feeding of dairy cows
    with food wastes containing dicloran residues.

    In processing and storage

    Chamberlain (1963 a,b) investigating the effect of home preparation
    and cooking on residues of dicloran on tomatoes, Brussels sprouts and
    beans found that tomatoes with obviously visible residues could not be
    cleaned satisfactorily by hand brushing. The removal of the visible
    deposit was easy using water. He carried out two series of tests on
    fruit picked 7 and 14 days after spraying. The fruit was analysed
    after a further 1, 3 and 6 days at room temperatures. Though the
    residue on the unclean fruit fell by about 30% (7 to 5.2 mg/kg) the
    simple cleaning, as might be practised in the home, reduced the
    residue from 7 to 0.5 mg/kg.

    Brussels sprouts dipped in dicloran at the standard rate of 0.2 kg of
    formulation per 100 l of water were found to have a residue of 3.8
    mg/kg. After simple washing the residue declined to 0.7 mg/kg.

    Green beans which had been dipped in dicloran suspension at
    recommended rates were cooked after being held in storage for 5
    different periods ranging from 7 hours to 13 days. Storage alone
    caused a decline in residues from 12 to 5.3 mg/kg, and normal domestic
    cooking caused a further loss of slightly more than 50% of the residue
    present before cooking. In a further series of experiments Chamberlain
    was able to show that of the initial dicloran deposit on beans,
    approximately 30% is lost in the cooking water, approximately 30% is
    lost through volatility in steam and 30 to 50% is retained by the

    The Upjohn Company (1968) carried out an extensive series of
    experiments in California designed to obtain registration for the use
    of dicloran for post-harvest treatment of peaches for canning. In
    these trials peach trees were sprayed with dicloran 13 and 1 days
    prior to harvest using both dust and wettable powder formulations. The
    harvested peaches were then dipped in dicloran suspensions under
    commercial conditions. The crop was then sampled for analysis and the
    remainder was subsequently canned commercially. The results indicate
    that only small residues (<0.05 mg/kg) result from the pre-harvest
    treatment but that the total residues following both pre- and
    post-harvest treatment range from 15 to 45 mg/kg with the bulk of the
    results being in the range of 20 to 30 mg/kg. None of the samples of
    canned peaches from the 16 separate trials contained any detectable
    residue of dicloran when analysed by microcoulometric gas
    chromatography with a limit of determination of 0.01 mg/kg.

    In a parallel series of experiments on plums/prunes the Upjohn Company
    determined the level of dicloran residues on unwashed, washed and
    washed and canned prunes that had been treated pre-harvest and
    post-harvest with dicloran. Whilst the residues on the unwashed fruit
    ranged up to 17.5 mg/kg in the case of dusted fruit and 8.7 mg/kg in
    the case of sprayed, washing reduced the residue level to the range of
    3 to 4 mg/kg. None of the canned fruit from any of the 16 separate
    treatments examined contained residues above 3.1 mg/kg showing that

    the washing and canning operation reduced the residues considerably,
    particularly those which were high owing to the pre-harvest
    application of dicloran dust.

    The Upjohn Company (1969) studied the effect of applying dicloran to
    grapes pre-harvest on the residue level in grapes and wine and on the
    fermentation and wine quality. Four types of wine grapes were treated
    once or twice at 13 and 7 days prior to harvest. The amount of
    dicloran used (2 and 3 kg/ha) was the maximum likely to be needed for
    the treatment of grapes. None of the grapes harvested 7 days after
    treatment and none of the fractions including juice, stem, pomace or
    fermented wine contained detectable residues. The analytical procedure
    based on microcoulometric gas chromatography had a limit of
    determination of 0.01 mg/kg.

    The wines produced from the grapes treated with dicloran were
    submitted to a taste panel and the report indicated no evidence that
    dicloran-treated grapes adversely affect the smell or taste of wine.

    In soil

    Van Alfen and Kosuge (1974) studied the effect of various
    micro-organisms on dicloran in liquid culture. Escherichia coli and
    Pseudomonas cepacia both converted dicloran to
    2,6-dichloro-p-phenylene diamine (DCPD) a 4-amino-3,5-dichloro
    acetailide (ADCAA). Culture fluids of an unknown bacterium yielded
    ADCAA but no detectable amounts of DCPD. The organisms differ in their
    capacity to produce these metabolites. P.Cepacia completely
    metabolized dicloran within 48 hours and accumulated ADCAA in the
    culture fluid as the major metabolite. E. coli rapidly utilised
    dicloran but accumulated DCPD as the major metabolite.

    Van Alfen and Kosuge (1976) carried out experiments with dicloran on
    samples of incubated soil. They found that after 3 days only 7% of the
    applied dicloran could be recovered and after 9 days only 3%. The
    major metabolite that was extractable from soil was identified as
    ADCAA. In the light of these findings it seems unlikely that any
    significant amount of dicloran would be available to be taken up by
    plants treated during the current or previous cropping cycle.
    Dejonckheere et al. (1975) compared the uptake of quintozene,
    hexachlorobenzene (HCB), dicloran and pentachloroaniline from soil by
    lettuce. They found that lettuce grown in soil containing 2.13 mg/kg
    of dicloran took up 0.13 mg/kg into lettuce harvested early in the
    season and 0.08 mg/kg in lettuce harvested two weeks later. The ratio
    of the concentration in lettuce to that in the soil was 0.04 in the
    case of dicloran, 0.53 in the case of quintozene and greater than 1 in
    the case of HCB.

    Casanova and Dubroca (1973) carried out an investigation of residues
    of various fungicides used in the treatment of lettuce crops under
    glass. They were able to show that following soil treatment
    considerable residues of quintozene appeared in harvested lettuce.

    Residues of dithiocarbamates could be kept within acceptable limits
    provided there was an adequate interval between treatment and harvest.
    In the case of dicloran even the application of a combined soil and
    foliage treatment gave rise to only very low residues.

    Evidence of residues in food in commerce or at consumption

    The U.S. Food and Drug Administration advises that during routine
    monitoring of raw agricultural commodities throughout the USA in 1975
    and 1976, 111 samples of fruits and vegetables were examined. Of these
    11 were found to contain dicloran residues above the US tolerances.
    Four of these were samples of cabbages for which there is no US
    tolerance and 5 were potatoes where the tolerance is only 0.25 mg/kg.
    The details are given in Table 3.

    The Netherlands Food Inspection Services reported that of 970 samples
    of domestically produced fruits and vegetables analysed in 1976 for
    dicloran 40 (4%) contained residues above national maximum residue
    limits. The bulk of these were cauliflowers (11), celery (9) and
    radish (9) for which the limit is only 0.1 mg/kg. Few violations
    occurred in samples of endive, lettuce and chicory where maximum
    residue limits have been established at 3, 3 and 1 mg/kg respectively.
    Details are given in Table 4.

    The Netherlands Food Inspection Services reported that of 663 samples
    of glasshouse lettuce collected at auction and analysed in 1975/1976
    89% contained less than 0.2 mg/kg of dicloran. Four samples contained
    dicloran residues above the limit of 3 mg/kg, 2 ranging up to 15


    Following the evaluation of dicloran in 1974, the Joint Meeting listed
    information that was required before maximum residue limits could be
    confirmed. Some of this information has been provided and was

    The question of wide variation in residue levels in berry fruits was
    considered in the light of further study of the extensive data
    evaluated in 1974. It was judged that the variations were normal and
    reflected the several species of berries involved, the different
    cultivars of each species and the varying ecological and environmental
    conditions. Experience with other pesticides applied to berries has
    indicated that spraying technique and spray equipment can also
    contribute to variations in residue levels.

    When exaggerated levels of dicloran are administered to pigs and
    cattle, significant residues can be found in various edible tissues
    with the highest concentration in liver. However, cows receiving
    rations containing dicloran residues at concentrations likely to be
    found in agricultural commodities following the use of dicloran
    produced milk without detectable traces of dicloran.

        TABLE 3. Dicloran Residues in Commerce, USA 1975/76


                     Cabbage     Carrots   Celery   Cherries    Lettuce   Okra   Peaches   Plums   Potatoes  Sweet Potatoes   Tomatoes


    0 - 0.10         2           4         2                    1         1      24                12        2                1

    0.101 - 0.30     1                     5                    1                14                3
    0.301 - 0.50     1                     4                    1                5                 2

    0.501 - 1.00                           1                    1                4         1       1         1

    1.001 - 2.00                                                1                5                 1         1

    2.001 - 3.00                                                2

    3.001 - 5.00                                                2                2
    5.001 - 10.00                                               3                1                 1
    >10.00                                          1           1
    Total            4           4         12       1           13        1      50        1       20        4                1

    Violations       4           0         0        0           1         1      0         0       5         0                0

        national tolerance

    TABLE 4A. Dicloran residues in Commerce, Netherlands, 1976


                   Endive   Lettuce   Purslane     Turnip-tops   Celery  Spinach   Corn salad    Cauliflower     Curled


    0.0 - 0.10     50       224       2            3             3       17        2             23              2
    0.101 - 0.30   2        126                    0             4                 2             11

    0.301 - 0.50   0        58                     0             4                                               

    0.501 - 1.00   3        49                     1             1

    1.001 - 2.00   2        41                     1

    2.001 - 3.00   1        10
           >3.00            4

    Total     970  58       512       2            5             12      17        4             34              2

    Violations 40  -        4         -            2             9       -         -             11              -

        = national tolerance

    TABLE 4B. Dicloran residues in Commerce, Netherlands, 1976


                   Savoy      Brussels      Butter bean   French     Chicory    Leek   Cucumber    Melon    Paprica        Tomato
                   Cabbage    sprouts                     bean
    0.0 - 0.10     1          7             7             29         150        2      22          7        11             24
    0.101 - 0.30               0                           1          19                1                                  1
    0.301 - 0.50              0                                      1                                                     1

    0.501 - 1.00              1                                      6

    1.001 - 2.00                                                     0

    2.001 - 3.00                                                     2

    Total          1          8             7             30         178        2      23          7        11             26
    Violations     -          1             -             1          2          -      -           -        -              1

        = national tolerance

    TABLE 4C. Dicloran residues in Commerce, Netherlands, 1976


                   Celeria    Beet root     Radish        Apple      Mushroom

    0.0 - 0.10     1          3             14            1          3
    0.101 - 0.30                            5

    0.301 - 0.50                            2

    0.501 - 1.00                            2

    1.001 - 2.00

    2.001 - 3.00

    Total          1          3             23            1          3
    Violations     -          -             9             -          -

        = national tolerance


    Simple washing processes remove over 90% of dicloran residues.
    Cooking removes approximately 50% of the residue from beans while the
    canning of peaches removes all delectable residue from fruit treated
    both pre- and post-harvest.

    No detectable residues (<0.01 mg/kg) of dicloran or its metabolites
    were found in wine made from grapes that had been treated with
    dicloran. No adverse effect on fermentation or quality of wine could
    be observed following the treatment of grapes shortly before harvest.

    Micro-organisms readily convert dicloran into
    2,6-dichloro-p-phenylenediamine and 4-amino-3,5-dichloroacetanilide.
    None of several studies indicate any appreciable uptake of residues of
    dicloran or its metabolites from soil by plants, including vegetables.


    On the basis of the additional information before the Meeting the
    temporary maximum residue limits previously recommended are confirmed
    as maximum limits. In addition the following limits are recommended.

              Commodity            Limit, mg/kg

              Onions                   20

              Nectarines               10

              Chicory                   1



    1. Further observations in humans.

    2. Results of further studies of the level and fate of dicloran
    residues on apricots and nectarines, particularly following
    post-harvest treatment.


    Allen, S.J., (1973) Dicloran residues on onions. Report of The Boots
    Company (Australia) dated 26th July 1973.

    Allen, S.J., Osborne, W.B., and Winton, E.C., (1973) Dicloran residues
    on peaches and nectarines following dipping in 1 % "Allison Col."
    -Report of The Boots Company (Australia) March 1973.

    Bachman, Goldberg and Thibodeau. Aspects of the determination of
    biphenyl hydroxylase activity in liver homogenates. 111. Influence of
    administration of 2,6-dichloro-4-nitroaniline to rats, Exp. Mol.
    Path., 14, 306, 1971.

    Casanova, M. and Dubroca, J. (1973)- Investigation of residues of
    various fungicides used in the treatment of lettuce under glass. (In
    French). Ann. Phytopathol., 5, 65-81

    Chamberlain, W.J. (2963a) - Allisan residues on tomatoes, Brussels
    sprouts and beans. Report to Boots Pure Drug Go. (Australia) Ltd. May

    Chamberlain, W.J. (1963b) - Fate of dicloran residues in beans. Report
    to Boots Pure Drug Co.  (Australia) Ltd. May 1963.

    Dejonckheer, W., Steurbant, W., and Kips, R.H. (1975) - Residues of
    quintozene, hexachlorobenzene in soil and lettuce. Bull. Envir. Contam
    & Toxicol. 13 (6) 720-729.

    Gallo, Bachmann and Goldberg. Mitochondrial effects of
    2,6-dichloro-4-nitroaniline and its metabolites, Tox. Appl. Pharm.,
    35, 51 (1976).

    Z. Hadidian, N. Frederickson, E.K. Weisburger, J.H. Weisburger, R.M.
    Glass and N. Mandel, J. Natl. Cancer Inst. 41: 9859 1968

    Hamilton, D.Y. (1977) - Tissue distribution of 14C-dicloran in rats,
    dogs and pigs following repeated oral dosing at 100 mg/kg/day. Boots
    Agrochemicals Research Report AC/DYB/636/236 27 July 1977.

    K.H. Jones, D.M. Sanderson and D.N. Noakes, Ibid. 7: 138, 1968.

    Maté, Ryan and Wright. Metabolism of some 4-nitroaniline derivatives
    in rat, Fd. Cosmet. Toxicol., 5. 657, (1976).

    Shirasu, Moriya, Kato, Furuhashi and Kada. Mutagenicity screening of
    pesticides in the microbial system. Mutation Res. 40, 19 (1976).

    The Upjohn Company (1968) - Residue determinations for DCNA on peaches
    before and after canning Report No. 212A-9760-1 to 10

    The Upjohn Company - Residue determinations for DCNA on grapes and in
    wine. Report No. (1969) 212-9760-5.

    Upjohn, Botran Clinical Study. (Unpublished report).

    Van Alfen, N.K., and Kosuge, T. (1974) - Microbial Metabolism of the
    fungicide 2,6-dicloro-4 nitroaniline. J. Agr. Food Chain. 22 (2)

    Van Alfen, N.K., and Kosuge, T. (1976) - Metabolism of the fungicide
    2,6-dichloro-4-nitroaniline in soil. J. Agr. Food Chem. 24, (3)

    Wright, W.M. (1968) - Dichloro-4-Nitroaniline. Residue Study in Milk
    Cows. -The Upjohn Company Report No. 212B-9760-6. Dated December 10,

    FAO/WHO (1975) 1974 evaluations of come pesticide residues in food.
    AGP:1974/M/11; WHO Pesticide Residues Series# No. 4.

    See Also:
       Toxicological Abbreviations
       Dicloran (ICSC)
       Dicloran (WHO Pesticide Residues Series 4)
       Dicloran (JMPR Evaluations 1998 Part II Toxicological)