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    PESTICIDE RESIDUES IN FOOD - 1981


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    EVALUATIONS 1981







    Food and Agriculture Organization of the United Nations
    Rome

    FAO PLANT PRODUCTION AND PROTECTION PAPER 42

    pesticide residues in food:
    1981 evaluations

     the monographs

    data and recommendations
    of the joint meeting
    of the
    FAO panel of experts on pesticide residues
    in food and the environment
    and the
    WHO expert group on pesticide residues

    Geneva, 23 November-2 December 1981

    FOOD AND AGRICULTURE ORGANIZATION OF THE UNITED NATIONS
    Rome 1982

    DELTAMETHRIN

    Explanation

         Deltamethrin was first evaluated in 1980 when, in the absence of
    an ADI, recommendations were made for guidelines for residue levels in
    a number of commodities.

         Additional information received since 1980 has been evaluated by
    the Meeting.

    DATA FOR THE ESTIMATION OF ACCEPTABLE DAILY INTAKE

    BIOCHEMICAL ASPECTS

    Absorption, distribution, excretion and biotransformation

    Rat

         Studies on rats to investigate uptake, distribution and excretion
    of deltamethrin were conducted with deltamethrin labelled with 14C in
    three positions (Ruzo  et al 1978a). The labelled deltamethrin was
    administered to male rats orally at levels of 0.64 to 1.6 mg/kg and
    resulted in the elimination of deltamethrin and various metabolites
    derived from its acid and alcohol fragments within 2 to 4 days.
    Metabolites of the cyano substituent were eliminated more slowly,
    especially from the skin and stomach, in the latter case owing to
    temporary retention of thiocyanate, which was formed from released
    cyanide. The excreted metabolites included: esters monohydroxylated at
    the 2',4' and 5 positions of the alcohol moiety; 2,2-dimethyl-3-
    (2,2,-dibromovinyl) cyclopropane carboxylic acid and its glucuronide
    and glycine conjugates and a hydroxylated derivative of this acid,
    with the hydroxymethyl group trans to the carboxyl and its
    glucuronide; 3-phenoxybenzoic acid and its glucuronide and glycine
    conjugates; 3-(4'-hydroxyphenoxy)benzoic acid and its glucuronide and
    sulphate conjugate and 3-(2'-hydroxyphenoxy)-benzoic acid sulphate,
    thiocyanate and 2-imino-thiazolidine-4-carboxylic acid. The trans
    isomer of deltamethrin was also rapidly metabolized in rats.

         Figure 1 illustrates metabolic pathways for deltamethrin in rats.
    The principal mechanisms of metabolism are ester cleavage and
    oxidation at the 4'-position of the alcohol moiety. Minor oxidation
    sites are the 5 and 2' positions of the alcohol moiety and the methyl
    group trans to the carboxyl. The ester metabolites are not conjugated,
    but the corresponding acids undergo extensive conjugation at both the

              

    *  See Annex II for FAO and WHO documentation.

    FIGURE 1

    phenolic hydroxyl and carboxylic acid groups. The acid moiety is
    rapidly excreted as the glucuronide, with smaller amounts as free and
    as the glycine conjugate. The trans-hydroxymethyl derivative is also
    excreted both free and as the glucuronide.

         All major metabolites of the aromatic portion of the alcohol
    moiety are rapidly excreted and probably arise from ester cleavage of
    deltamethrin or its ester metabolites, conversion of the released
    cyanohydrins to the aldehydes which rapidly yield the corresponding
    acids and conjugates of these acids. Table 1 illustrates the
    radiocarbon in the urine, faeces, carbon dioxide and tissues of rats
    up to 8 days after oral administration of labelled deltamethrin.

    TABLE 1.  Radiocarbon in the urine, faeces, carbon dioxide, and
              tissues of rats up to 8 days after oral administration
              of 14Cv, 14Cai.e, alpha &: 14CN deltamethrin.
                                                                        

                                       Labeling position
                                                                        

          Sample analyzed              14Cva,b      14Calpha      14CN
                                                                        

                           Administered Dose, mg/kg

                                       0.90         1.60          0.64

                            % of Administered Dose

    Urine
      0-1 day                         45.1         67.6           10.4
      1-2 days                         5.6          3.0            8.1
      2-4 days                         2.7          2.1           11.4
      4-8 days                         1.0          1.0           13.0
    Feces
      Methanol extract

        0-1 day                       35.6         22.7           12.1
        1-2 days                       2.0          1.8            2.3
        2-4 days                       1.7          0.3            3.3
        4-8 days                       0.4          0.0            3.3
      Unextractable, 0-8 days          4.4          0.4           14.7
    14CO2, 0-2 days                    0.0          0.0            0.0
    Carcass and tissues, 8 days        1.5          1.1           21.4
                                                                        

    TABLE 1.  (con't)

                                                                        

                                       Labeling position
                                                                        

          Sample analyzed              14Cva,b      14Calpha      14CN
                                                                        

            Tissue Residue at 8 Days, ppb of Decamethrin Equiv

    Blood                             12           89            103
    Bone                              12           11             57
    Brain                              4           20              5
    Fat                               59          182             94
    Heart                              8            9             41
    Intestine
      Large                            9            5             77
      Small                           10            5            129
    Kidney                             8           10             66
    Liver                             12           38             66
    Lung                               4            5             73
    Muscle                             5            5             57
    Skin                              16           16            603
    Spleen                             2            5             49
    Stomach                            8            3            654
    Testes                             5            3             54
                                                                        

    a  With (1RS)-trans-[14Cv]decamethrin administered orally at
    0.94 mg/kg, the 14C balance sheet at 8 days as percent of dose is
    72.6% in urine (48.6% at 1 day, 62.3% at 2 days, and 71.2% at
    4 days), 23.2% in the methanol extract of feces (12.3% at 1 day,
    18.6% at 2 days, and 21.7% at 4 days), 3.0% in the unextractable
    portion of feces (0-8 days), and 1.2% in carcass and tissues (all
    individual tissues as above < 10 ppb decamethrin equivalents),

    b  With [14Cv]Br2CA administered orally at 3.74 mg/kg, the 14C
    balance sheet at 8 days as percent of dose is 94.0% in urine (70% at 
    1 day, 82% at 2 days, and 91% at 3 days), 5.8% in feees (5.4% in methanol
    extract), 0.0% 14CO2, and 0.2% in carcass and tissues. The tissue
    residues are < 3 ppb decamethrin equiv except for liver which is
    27 ppb.

         The pathways involved in rat metabolism of deltamethrin isomers
    are similar to those utilized for other pyrethroids in many segments
    of the ecosystem (Elliott 1977; Gaughan  et al 1977a, b).

         The tissue distribution of toxic doses of 14C-acid,
    14C-alcohol-, and 14C-cyano labelled deltamethrin after i.v.
    administration to rats has been studied (Gray and Richard 1981). All
    three radiolabelled preparations were found in every tissue examined
    1 min. after injection. Peak CNS levels were achieved within 1 to
    5 min. but did not correspond to the onset of choreoathetosis. In the
    majority of tissues examined, the levels of deltamethrin label were
    similar, proportionately to those found after administration of
    alcohol labelled cismethrin. A major exception was the CNS, which
    contained approximately 20% of the anticipated level of radiolabel,
    suggesting that the CNS threshold for deltamethrin was approximately
    0.5 to 1.0 nmol/g. Progressive accumulation of radioactivity in the
    erythrocytes fraction of the blood was observed following
    administration of cyano-labelled deltamethrin; it was suggested that
    this may contribute to the selective retention of 14C with
    radiolabelled preparations.

    Mouse

         Studies on mice to determine oxidative, hydrolytic and
    conjugative reactions were conducted with (14Calpha) and (14Cv)
    labelled deltamethrin (Ruzo  et al 1979). The labelled deltamethrins
    were orally administered to two mice each at 3.1 and 3.6 mg/kg
    respectively and the animals sacrificed 6 h later. The 14C label was
    rapidly and almost completely excreted, with little tissue retention
    after 8 days (Table 2).

         Deltamethrin metabolism in mice involved four sites of oxidative
    attack (trans-methyl group of the acid moiety and 2', 4' and 5
    positions of the alcohol moiety, hydrolysis and a variety of
    conjugation process) (Figure 2). Mice excrete less unmetabolized
    deltamethrin than rats (Ruzo  et al 1978) suggesting more efficient
    absorption and/or metabolism. Mice produce considerable amounts of the
    trans-, 2'- and 5'-hydroxy derivatives, whereas rats hydroxylate
    deltamethrin predominantly at the 4'-position.

         The acid moiety is rapidly excreted as the glucuronide with
    smaller amounts free and as the glycine conjugate. The trans hydroxy
    methyl derivative is also excreted free, as the glucuronide and as the
    sulphate conjugate; the latter was not detected in rats.

         Metabolites in mouse, but not rat, excreta include: 3-2(2,2-
    dibromovinyl)-2-trans-hydroxymethyl-2-methylcyclopropanecarboxylic
    acid sulphate; 3-phenoxybenzaldehyde; 3-phenoxybenzyl alcohol and its
    glucuronide; glucuronides of 4'-hydroxy-3-phenoxybenzyl alcohol and
    5-hydroxy-3-phenoxybenzoic acid and 3-phenoxybenzoyltaurine.
    Intraperitoneal (i.p.) administration of deltamethrin to the mouse
    yielded the same metabolites, but in different ratios. Deltamethrin is
    detoxified in mice by both oxidative and hydrolytic processes.

    TABLE 2.  Radiocarbon in the urine, faeces, and tissues of mice up
              to 8 days after oral administration of 14Cv, 14Ca
              i.e, alpha & 14C deltamethrin.
                                                                    

                                           labeling position
                                                                    

         sample analyzed          14Cv           14Calpha       14CN
                                                                    

                           Administered Dose, mg/kg

                                   4.4           1.7            2.2

                            % of Administered Doseb
    urine
      0-1 day                     28.9          40.5           13.1
      1-2 days                    13.8           5.0            8.5
      2-5 days                    12.0          15.7           10.3
      5-8 days                     2.6           3.9            3.6

    feces
      methanol extract

        0-1 day                   19.0          18.6           20.8
        1-2 days                   9.5           4.0           16.4
        2-5 days                  72             5.1            4.5
        5-8 days                   0.9           0.4            2.2
      unextractable, 0-8 days      5.1           5.8           13.8
    carcass and tissues, 8 days    1.0           1.0            6.8

         Tissue Residue at 8 Days, ppb of Decamethrin Equivc

    blood                          4             5             54
    brain                         17             0              4
    fat                          273           115             79
    kidney                        39            27             20
    liver                         47            20             19
    skin                          77             3            778
    stomach                       28             9            175
                                                                    

    a  Values at 3 days are given in Table 1 of the microfiche
    supplement to this report.
    b  14CO2 values are <0.1% for 0-2-day samples with each labeled
    preparation.
    c  Comparable values for bone, heart, intestine, lung, muscle,
    spleen, and testes are <60 ppb.

    FIGURE 2

        TABLE 3.  Acute toxicity of deltamethrin
                                                                                           

                                                 LD50
    Species             Sex       Route          (mg/kg bw)     References
                                                                                           

    Mouse               M+F       iv                41          Glomot and Chevalier 1976c
                        M         ip               181          ibid 1976b
                        M         ip              1712          ibid 1976b
                        M         oral             211          ibid 1976a
                        M         oral             332          ibid 1976a
                        F         io               121          ibid 1976b
                        F         ip              1662          ibid 1976b
                        F         oral             191          ibid 1976a
                        F         oral             342          ibid 1976a

    Rat                 M+F       iv               311          ibid 1976c
                        M         ip               241          ibid 1976b
                        M         ip              2092          ibid 1976b
                        M         oral             671          ibid 1976a
                        M         oral            1282          ibid 1976a
                        M+F       inhal.            0.63        Coombs and Clark 1978
                        M+F       dermal        <29404          Kynoch et al 1979
                        F         ip               251          Glomot and Chevalier 1976b
                        F         ip              1862          ibid 1976b
                        F         oral             861          ibid 1976a
                        F         oral            1392          ibid 1976a

    Rabbit              M+F       dermal        >20005          Clair 1977

    Dog (beagle)        M+F       oral           >3001          Glomot et al 1977
                        M+F       oral           >3006          ibid

    Chicken                       oral        ca 10002          Roussel Uclaf 1976a

    Hen (adult)         F         oral          >25002          Ross et al 1978
                        F         oral          >50007          ibid

    Mallard duck                  oral          >46407          Beavers and Fink 1977a

    Game duck                     oral          >40006          Roussel Uclaf 1976b

    Grey Partridge      M+F       oral          >18007          ibid

    Red Partridge       M+F       oral          >30007          ibid
                                                                                           
    1  Suspended in polyethylene glycol 200;  2  dissolved in sesame oil;
    3  expressed for LC50 in mg dust/m3 air;  4  60% w/v suspension in aqueous
    methyl-cellulose in occlusion;  5  as paste in PEG 400 on occlusion;
    6  in capsules or cachets;  7  dissolved in maize oil.
    
    Pretreatment with either the oxidase inhibitor piperonyl butoxide or
    the esterase inhibitor S,S,S-tributyl phosphorotrithioate (DEF)
    further increased deltamethrin in mice, reduced its rate of  in vivo 
    metabolism by hydroxylation and hydrolysis, reduced the rate of
    product excretion and elevated deltamethrin levels in fat and brain
    (Ruzo  et al. 1979; Soderlund and Casida 1977).

         Deltamethrin-hydrolysing esterases are generally sensitive to
    organo-phosphate inhibition (e.g. TEPP inhibition of hydrolysis by
    all tissue preparations except stomach). The two major factors
    contributing to the rapid detoxification of decamethrin are: a) the
    relevant esterases present in many tissues and the oxidases in, at
    least, liver microsomes, and b) many molecular sites that are
    susceptible to metabolic attack (Ruzo  et al 1979).

         There are large differences in the toxicity of deltamethrin to
    mice, depending on the route of administration, the carrier vehicle
    and previous exposure to piperonyl butoxide or DEF. Irrespective of
    these factors, there appears to be a critical concentration of
    deltamethrin in brain that correlated with the onset of tremors or the
    time of death. Additionally, direct intracerebral administration of
    deltamethrin at approximately this brain level gave a similar
    poisoning effect. The brain appears to be a primary target in
    deltamethrin poisoning of mice (Ruzo  et al 1979).

    Rat

         The signs of toxicity observed in rats after deltamethrin
    administration included salivation and choreoathetosis (a writhing
    type of toxicity) (Barnes and Verschoyle 1974; Ray 1980; Ray and
    Cremer 1979; Verschoyle and Aldridge 1980) and have been designated as
    the CS syndrome of toxicity (Verschoyle and Aldridge 1980).

         Rats injected i.v. with deltamethrin showed muscular
    contractions, piloerection, respiratory defects, convulsions and
    paresis of the hind quarters immediately following treatment. Death
    occurred within 10 min. After 24 h only piloerection was visible;
    after 48 h surviving animals showed normal behaviour. After i.p.
    injection immediate tremors, convulsions, prostration and cyanosis
    were observed. After 48 h surviving animals showed normal behaviour.
    Gavage with deltamethrin shortly after dosing induced motor
    incoordination, convulsions and respiratory defects. After 24 and
    48 h, hypomotility and convulsions were still observed. After 3 days
    surviving animals showed normal behaviour (Glomot and Chevalier
    1976a,b,c).

         In an earlier study, the acute i.v. lethal dose in young adult
    female rats was 2 to 2.5 mg/kg when administered as a solution in
    glycerol formal (Barnes and Verschoyle 1974). Signs of poisoning
    included excessive salivation without lacrimation, rapidly followed by

    continuous jerking movements of the limbs, occasionally progressing to
    convulsions. The toxic effects were rapid in onset and brief in
    duration. Death occurred in some animals within 12 min of dosing while
    survivors were generally symptom-free within 6 h. In a more recent
    study (Kavlock  et al 1979, see Table 4), the acute LD50 for adult
    female rats was 31 mg/kg by the oral route and 4 mg/kg by the i.v.
    route. The LD50 was observed to be sex and age dependent, with higher
    values found for weanlings and males. Initial signs of deltamethrin
    poisoning included profuse salivation and convulsive movements;
    weakness, dyspnoea, anorexia and staining of the fur were observed
    beyond the first day following compound administration.

         Rats (7 males and 7 females/group) were exposed (whole body)
    during 6 h to aerosols of a.i., aerosol concentration being 0.049,
    0.43, 0.54 and 0.72 g/m3. The aerosol contained 66 to 86% of
    particles < 5.5 . During exposure, hyperactivity and dose-dependent
    increase in grooming and irritation were observed. The animals were
    hypersensitive to touch and noise and showed uncoordinated movements.
    During the observation period of 14 days following exposure, all
    animals except those from the lowest dose group developed poor motor
    coordination and hypersensitivity. At the end of the period all
    animals were recovered to normal. In these groups the body weight gain
    and food intake was depressed during 3 days following exposure. In
    rats (4 of control and of highest dose group) killed immediately after
    exposure, the stomach and small intestine were gas filled. In treated
    rats, as result of exposure, massive haemorrhage and oedema in lungs
    were observed. Stomachs were filled with gas, blood and mucus. White
    deposits were visible in the trachea. In animals killed after the
    observation period, a dose-dependent increase of lung degeneration
    (coloured spots to congestion) was observed (Coombs and Clark 1978).

    Mouse

         Mice injected i.v. with deltamethrin showed intense tremors,
    convulsions and ataxia immediately after administration. Also,
    tachycardia and respiratory defects were observed at higher doses.
    Surviving animals showed normal appearance after 4 to 5 h. Immediately
    after i.p. injection, jumping movements, slight convulsions and
    prostration, ptosis, tail hypertonicity and cyanosis were observed.
    Surviving animals appeared normal after 72 h. Animals gavaged with
    deltamethrin showed muscular stiffening and convulsions 1 h after
    dosing. After 24 h hypermotility, stereotype movements of the head,
    tachycardia, hypertonicity of the tail and a few convulsions were
    noted. Normal behaviour and appearance were seen after 48 h (Glomot
    and Chevalier 1976a,b,c).

        TABLE 4.  Acute toxicity of deltamethrin to rats1
                                                                                                                                           

                                                                     95 % Confidence     Lowest dose         Minimum Toxic
    Route               Strain              Sex       Age            LD50                limit of            tested              Dose
                                                                     mg/kg               LD50 (mg/kg)        (mg/kg)             (mg/kg)
                                                                                                                                           

    Oral2               Sherman             M         Adult          52                  46 - 58             30.00               306

    Oral2               Sherman             F         Adult          31                  29 - 34             5.00                107

    Oral2               Sherman             F         Weanling       50                  42- 60              7.50                157

    Intravenous3        Sherman             F         Adult          4                   2.9-5.3             1.57                1.576

    Intravenous3        Sherman             F         Weanling       1.8                 1.5-2.1             0.78                0.76

    Dermal4             Sherman             F         Adult         >800                 ---                 800:0               --- 8

    Inhalation5         Sprague-Dawley      M         Adult          940 mg/m3           ---                 ---

    Inhalation5         Sprague-Dawley      F         Adult          785 mg/m3           ---                 ---
                                                                                                                                           

    1  Reference-Kavlock et al 1979;
    2  Dissolved in peanut oil and administered via gavage at a rate of 5 ml/kg bw;
    3  Dissolved in acetone and administered via a single injection into tail vein of rat at 0.313 ml/kg bw;
    4  Dissolved in xylene and administered at a rate of 3.2 ml/kg bw;
    5  Aerosols generated from 10% DMSO solution. Based on exposure time of 120 to 150 min.;
    6  Moderate to severe salivation and convulsions;
    7  Mild salivation;
    8  No signs of toxicity at 800 mg/kg.
        Rabbit

         Rabbits (10 males and 10 females) were treated with 2 g
    deltamethrin in 2 ml PEG 400/kg bw on 80 cm3 shaven skin for 24 h on
    occlusion. The animals were observed for 14 days. One animal showed
    obvious erythema and another congested skin. No weight changes or
    abnormal behaviour were observed. On histological observation of
    liver, kidneys and skin, small changes were observed that were common
    for this strain of rabbits and not related to treatment (Clair 1977).

    Dog

         Dogs showed, at non-lethal doses, transient hyperexcitability,
    akynesia, vomiting and stiffness of the hind legs (Glomot  et al 
    1977).

    Birds

         Oral administration of a.i. to hen, game duck or partridge
    produced no distinct symptoms except a small initial weight loss
    occasionally. In chickens diarrhoea, convulsions and jerky movements
    of the head were observed. Mallard ducks, at lethal doses, exhibited
    signs of neurotoxic effects, which included ataxia, loss of
    equilibrium and loss of coordination. The effect was dose-related: at
    lower dose levels only some hyperexcitability and imbalance were
    observed (Beavers and Fink 1977a).

    Short-term studies

    Rat

         Male and female weanling Sprague-Dawley rats (20/sex/group)
    were daily dosed by oral gavage with 0, 0.1, 1.0, 2.5 or 10.0 mg
    deltamethrin in PEG 200/kg bw/day for 13 weeks (Hunter  et al 1977).
    No treatment-related effects on food and water consumption, mortality,
    urinalysis and haematology were observed. Neurological examinations
    and ophthalmoscopy revealed no abnormalities. In the 10 mg/kg bw
    group, some hypersensitivity was observed in week 6 in males. Body
    weight gain among males receiving deltamethrin was significantly lower
    at 2.5 and 10 mg/kg/day. The body weight of the females was not
    affected by the treatment. The male animals of the 1 mg/kg group
    showed a tendency to a reduced body weight gain. In the females, blood
    glucose and urea were significantly increased in week 6, but no
    significant changes occurred in week 12 or with other blood chemistry
    parameters. No clear effects were noted on the weights of the organs.
    Gross and microscopic examination of a variety of tissues and organs
    showed no treatment-related alterations.

         Following the 13-week dosage period, 5 males and 5 females per
    group were allowed to recover for 4 weeks. Autopsy was performed at
    the end of this recovery period. The body weights of all previously
    treated animals appeared not to be different from controls. Thyroid
    weights were not dose-related but were increased in males. This
    increase was significantly higher in the 1.0 mg/kg and 10.0 mg/kg
    group. Marginal no-effect level was 1 mg/kg bw (Hunter  et al 1977).

    Dog

         Male and female beagle dogs, 3-5/sex/group, 25 weeks of age, were
    daily dosed orally with 0, 0.1, 1.0, 2.5 and 10.0 mg deltamethrin in
    PEG 200/kg bw/day in gelatin capsules. Dosage was continued for 13
    weeks, followed by a recovery period of 20 weeks for 2 dogs/sex from
    the groups receiving 1.0, 2.5 and 10.0 mg/kg bw/day (Chesterman
     et al 1977). Observations were made on behaviour, mortality, body
    weight and food and water consumption. Haematology, blood chemistry,
    urinalysis and six channel EEG-analysis were performed at week 0, 6
    and 1, and ophthalmoscopy at week 0, 5 and 12. Special attention was
    paid to the muscular and nervous systems.

         Liquid faeces were associated with all groups of treated dogs
    throughout the dosing period. All groups of animals receiving
    deltamethrin gained less weight than the controls. The effects were
    not strictly dose related. The dogs from the control group left
    smaller quantities of the offered food than those of the treated
    groups, whereas the water consumption was not dose-relatedly decreased
    in all treated groups.

         Dilation of the pupils was seen to occur in the dogs receiving
    2.5 and 10.0 mg/kg/day. The sign was first seen 4 to 7 h after dosing
    and persisted throughout the day. They reacted normally prior to
    dosing on the following day. The incidence of vomiting was dose-
    related increased in all treated groups, except the 0.1 mg dose level.
    The incidence decreased in all the animals affected as the dosing
    period progressed. In the highest dose group, unsteadiness, body
    tremors and jerking movements were seen, particularly in males in
    weeks 2, 3 and 4. These effects were reduced during week 5 to 9 and
    were seen only in one dog in week 13. Excessive salivation was seen
    initially but diminished during dosing period. After 5 and 12 weeks,
    depression of the gag reflex was noted in a proportion of animals in
    all treated groups. Depression of the patellar reflex was observed in
    all treated groups except the dogs administered 0.1 mg/kg. In the
    animals given 1 or 2.5 mg/kg/day, exaggeration of the patellar reflex
    was noted only after 5 weeks. Some animals of all treated groups
    showed variations in the flexor reflex. A high proportion of the
    animals had depression of the hind limb tactile placing reaction.

         At dosage levels of 2.5 and 10 mg/kg/day, deltamethrin caused
    modification of the EEG pattern in some animals following 12 weeks
    administration. Histopathological evaluations of tissues and organs,
    including nervous system and muscle, did not reveal abnormalities that
    could be related to dosage with the test compound. During recovery the
    gag reflex continued to be depressed, whereas exaggeration of the
    patellar reflex was still seen in some dogs that had previously
    received 1.0 mg/kg/day. One animal continued to show an abnormal EEG
    pattern (Chesterman  et al 1977).

    Quail and duck

         Deltamethrin was given in the diet to 14-day old mallard ducks
    for 5 days, at doses of 0, 464, 1 000, 2 150, 4 640 and 10 000 mg/kg
    feed. The number of animals per group was 10. There was some mortality
    in the two highest dose groups. Birds of the highest dose group showed
    ataxia and loss of coordination. There were dose-related decreased
    weight gain and food consumption (Beavers and Fink 1977a).

         An identical experiment was performed with 14-day old bobwhite
    quails (10 animals/group). The effects were the same as in the mallard
    ducks, except there was no mortality (Beavers and Fink 1977b).

    Long-term studies

    Rat

         Male and female Charles River CD rats (90/sex/group) were dietary
    fed with 0 (control), 2, 20 and 50 mg deltamethrin/kg in the diet for
    two years. Sixty males and 60 females were used in a second control
    group. After 6, 12 and 18 months of compound administration, 10
    animals/sex/group were sacrificed, except for the second control group
    (Goldenthal  et al 1980b).

         No changes in general behaviour and appearance in relation to
    compound treatment were recorded. Survival was similar in control and
    treated rats (50 to 67%). Rats at 50 mg/kg feed gained slightly less
    weight than control rats, whereas the food consumption was essentially
    the same. Ophthalmoscopic findings generally were similar for control
    and treated rats. No haematological and biochemical parameters were
    changed in a biologically significant way in relation to treatment at
    any time, except for a decreased SGPT activity at 6 months in the mid-
    and high-dose groups. No treatment-related effects were observed on
    organ weights. The macroscopy and microscopy findings were common for
    the animals of the species and strain, except for a slightly increased
    incidence of axonal degenerations in sciatic, tibial and/or plantar
    nerves at 18 months in the 20 and 50 mg/kg groups. Evaluation of
    incidence and/or severity of these degenerations at termination of the
    study was obscured by the age of the animals.

         Seven interstitial cell adenomas were observed in the testes of
    the 50 mg/kg feed group compared to 0 and 4 in the two control groups.
    Only from some animals of the 2 and 20 mg/kg groups were some organs
    and tissues, including the testes, studied histopathologically.
    Evaluation of a possible dose-response effect on the testes was
    therefore not possible. The no-effect level was suggested to be
    2 mg/kg (Goldenthal  et al 1980b).

    Mouse

         Male and female Charles River CD-1 mice (80/sex/group) were fed
    dosage levels of 0(control), 1, 5, 25 and 100 mg deltamethrin/kg in
    the diet for 24 months. In a second control group 60 mice/sex were
    used. After 12 and 18 months 10 mice/sex/group, except for two only in
    the control group, were sacrificed.

         There were no clear effects related to the administration of
    deltamethrin on general behaviour, mortality, body weight and food
    consumption. Blood chemistry, haematology and urine analysis
    parameters were normal after 12, 18 and 24 months. Increases or
    decreases in absolute and/or relative organ weights occurred in a few
    organs at each dosage level at any time of sacrifice. Microscopic
    examination of tissues did not reveal any lesions indicative of a
    compound-related effect. The tumour incidence was unaffected by
    deltamethrin administration. The no-effect level was suggested to be
    100 mg/kg (Goldenthal  et al 1980a).

         Studies designed to investigate the potential carcinogenic
    effects of deltamethrin have been initiated (Cabral 1981). Groups of
    C57B1 mice have been administered orally 0-8 mg/kg bw deltamethrin in
    arachis oil.

    Dog

         Deltamethrin (RU 22974) dissolved in maize oil was administered
    in the diet to 64 beagle dogs at dosage levels of 1, 10 and 40 ppm for
    24 months. This corresponds to 0.025, 0.25 and 1 mg/kg bw respectively
    (IRDC 1980). Eight males and eight females were used at each dosage
    level and in a control group. Individual body weights and food
    consumption values were determined weekly. Ophthalmic, haematologic,
    biochemical and urinalysis examinations were conducted during the pre-
    test period at 6, 12, 18 and 24 months of the study. Neurological
    exams were conducted at approximately 1 year and before termination.
    These later parameters included: for cranial nerves and segmental
    nerves, tests for postural reactions, placing reactions and hopping
    reactions.

         No signs of overt toxicity were observed in any of the dogs. Body
    weights and food consumption values were similar for control and
    treated dogs. No compound-related effects were observed during the

    ophthalmoscopic and physical examinations. Although there were some
    randomly statistically significant differences between the control and
    other dose groups in the haematologic and biochemical tests, there
    were not any physiologically significant changes observed at any
    interval in the study. Two treated and two control animals died during
    the study.

         No compound-related gross or microscopic changes were observed in
    the surviving dogs that were sacrificed and necropsied. Inflammatory,
    degenerative and proliferative changes described were spontaneous in
    nature or related to theoestrous phase of the menstrual cycle and
    unrelated to compound administration.

         On the basis of the results from this study, it was concluded
    that the no-effect level is 40 ppm in the diet (equivalent to
    1 mg/kg bw/day) administered RU 22974 over a 2-year period (IRDC
    1980).

    Special studies on primary irritation

    Cutaneous irritation

         Male albino rabbits (12/group) weighing 2.5 to 3.5 kg were
    administered 0.5 g deltamethrin to either shaven intact or abraded
    skin. The occlusive patch was fixed on the skin for 23h. Scoring for
    erythematous and oedematous lesions occurred 1 h and 49h after removal
    of the patches. Technical deltamethrin, 98% a.i., showed no irritant
    effect (Coquet 1976a).

    Ocular irritation

         Deltamethrin (0.1 g/animal) was administered into the
    conjunctival sac of the eye of 6 male albino rabbits, weighing 2.5 kg,
    with or without rinsing 60 sec. after instillation. Observations for
    conjunctival lesions, chemosis, discharge, conjunctival enanthema,
    opacity and affected cornea were made 1 h, 24h, 2,3,4 and 7 days
    following instillation. Deltamethrin showed, both with and without
    rinsing, transient irritating effects (Coquet 1976b).

    Special studies on sensitization

         Deltamethrin (0.5 g/animal) was applied topically to the skin of
    albino guinea pigs with a 2-day interval for 3 weeks, and once at the
    start of the 4th week. The preparation was covered with an occlusive
    patch for 48h. On days 1 and 10 the guinea pigs received an
    intradermal injection of 0.1 ml of Freund's adjuvant. The animals were
    challenged 12 days after the last application with 0.5 g deltamethrin.
    The macroscopic and histological examination did not reveal evidence
    of sensitization (Guillot and Guilaine 1977).

    Special studies on reproduction

    Rat

         Groups of 10 female and 10 male Charles River rats were fed
    deltamethrin in the diet at 0, 2, 20 and 50 mg/kg and mated to begin a
    three-generation, 2 litter (first generation, 3 litter) standard
    reproduction study. Parental body weights and food consumption were
    recorded during the study. After weaning of the second litter, the
    survival parental rats were sacrificed and necropsied. Five male and
    5 female pups of the F3b were necropsied. No changes in general
    behaviour or survival of parental rats or pups relevant to the test
    material were observed. The body weight of F0 males of the 50 mg/kg
    group was decreased from week eleven onwards. There was some slight
    decreases in mean food consumption of the parental F1 male rats in
    the 50 mg/kg feed group.

         The basic reproduction indices (fertility, gestation, lactation,
    viability and litter size) were not affected by the treatment.
    However, the mean pup weight was affected in some litters; especially
    that of the 50 mg/kg group was slightly decreased in comparison to the
    controls. Gross external examination revealed no abnormalities. No
    gross or microscopic lesions of treatment-related significance or
    significant effects on the organ weights of the F3b generation were
    observed (Wrenn  et al 1980).

    Special studies on teratogenicity

    Mouse

         Mated female Swiss CDI.SPF mice (24/group) were given orally
    deltamethrin dissolved in sesame oil at dose levels of 0, 0.1, 1 and
    10 mg/kg bw/day during days 6 to 17 of pregnancy. The animals were
    necropsied on day 18 of gestation. No teratogenic effects could be
    detected. Total implantation sites, foetal losses, living foetuses and
    examinations of skeletal tissue were normal. Minor embryotoxic effects
    were observed, e.g. dose-dependent decrease of average foetal weight
    and delayed ossifications at all dose levels tested (Glomot and
    Vannier 1977).

         Technical deltamethrin (Roussel UCLAF), dissolved in corn oil was
    administered to CD-1 mice by gastric intubation at doses of 12.0, 6.0,
    3.0 or 0 mg/kg during days 7 to 16 of gestation (Kavlock  et al 
    1979). Maternal weight on day 6 was used for calculation of doses and
    intubation was 0.2 ml; control animals received vehicle alone. Animals
    were sacrificed on day 16 of gestation. Administration of deltamethrin
    to pregnant mice resulted in a dose-related (p < 0.001) reduction in
    maternal weight gain during pregnancy. Pregnant dams in the high
    dosage group (12.0 mg/kg/day) gained 58% less weight than did those in
    the control group. No dose-related occurrences of maternal mortality

    were observed, but most animals in the high dosage group and some in
    the middle dosage group became convulsive soon after dosing. No
    effects were observed on the number of implantation sites, foetal
    mortality, or foetal weights, or in the number of sternal and caudal
    ossification centers. A significant (p < 0.01) dose-related increase
    in the occurrence of supernumerary ribs was observed. No other dose-
    related skeletal or visceral anomalies were observed in deltamethrin-
    treated mouse foetuses. No evidence of teratogenic activity was found
    in mice at dose levels that produced maternal toxicity (Kavlock
     et al 1979).

    Rat

         Mated female Sprague-Dawley rats (24/group) were administered
    orally 0, 0.1, 1 and 10 mg deltamethrin/kg bw/day during days 6 to 18
    of pregnancy. Examination occurred on day 21 of gestation. Twelve
    females in the control and 10 mg/kg bw groups were allowed to deliver.
    There were no effects on the reproduction or teratogenicity parameters
    examined, with the exception of a slight delayed ossification in the
    highest dose level (Glomot and Vannier 1977).

         Technical deltamethrin (Roussel UCLAF) dissolved in maize oil was
    administered to Sprague-Dawley rats by gastric intubation at doses of
    5.0, 2.5, 1.25 or 0 mg/kg during days 7 to 20 of gestation (Kavlock
     et al 1979), Maternal weights on day 6 were used for the calculation
    of doses and intubation volume was 0.2 ml; control animals received
    the vehicle alone. Rats were sacrificed on day 21 of gestation.
    Administration of deltamethrin to pregnant rats resulted in a dose-
    related reduction (p > 0.01) in maternal weight gain during
    pregnancy, with animals in the high dosage group (5.0 mg/kg) gaining
    only 80% of the control value. This dose produced a mild salivation
    for up to 4 h after dosing in approximately 50% of the animals. No
    effects were observed on the number of implantation sites, foetal
    mortality, foetal weight or number of sternal and caudal ossification
    centres. For post-natal studies, an additional group of pregnant rats
    was housed individually and intubated from day 7 of gestation to day
    15 of lactation with dosages of either 5.0, 2.5 or 0 mg/kg
    deltamethrin dissolved in maize oil. No persistent toxicity was
    observed in neonatal rats that received perinatal exposure to
    deltamethrin (Kavlock  et al 1979).

    Rabbit

         Groups of fifteen mated females received deltamethrin dissolved
    in sesame oil at levels of 0, 1, 4 or 16 mg/kg bw/day from days 6 to
    19 of pregnancy. Examination was carried out on day 28 of gestation.
    The average foetal losses were not dose-related and increased at all
    doses tested. This effect was mainly caused by a higher rate of
    expelling traces. The average foetal weight in the highest dose group
    was decreased. Some malformations (one animal with hydrocephalia, and

    one with exencephalia and thoracogastroschisis) were observed in
    2 animals of the highest dose level. A complementary study with
    15 mg/kg bw/day was performed. In this study one foetus with spina
    bifida and shortened tail was detected among 69 parent normal
    foetuses. It was concluded that the malformations were within the
    normal limits of the strain used and were not related to the
    treatment, despite the occurrence at the highest dose level only
    (Glomot and Vannier 1977, 1978).

    Special studies on neurotoxicity

         Adult hens (10/group) were gavaged with a single dose of 0, 500,
    1 250 or 5 000 mg/kg bw deltamethrin suspended in maize oil or 0 and
    1 000 mg/kg bw dissolved in sesame oil. Tri-o-cresylphosphate (TOCP)
    (500 mg/kg bw) was used as positive control for delayed neurotoxicity.
    During 21 days, observations were made on mortality, health,
    neurotoxic signs and body weight.

         In the TOCP group, 8 out of 10 animals died whereas only
    2 mortalities were observed in the group dosed at 1 000 mg
    deltamethrin/kg with sesame oil as the vehicle. Deltamethrin
    induced no clinical, macroscopic or histological signs of delayed
    neurotoxicity. TOCP-treated hens showed severe ataxia and degenerative
    changes in the spinal cord and, occasionally, in the sciatic nerve
    (Ross  et al 1978).

    Special studies on potentiation

    Mice

         Deltamethrin is hydrolysed in vitro by esterases in blood and in
    brain, kidney, liver and stomach preparations of mice. Pre-treatment
    of mice with oxidase inhibitor, piperonyl butoxide (PB), or esterase
    inhibitor, S, S, S-tributylphosphorotrithioate (DEF), delayed
    metabolism of i.p. administered deltamethrin. Using oxidase or
    esterase inhibitor, different vehicles and different administration
    routes, it was possible to induce similar toxic effects with a wide
    range of deltamethrin doses (6 to 191 mg/kg bw). The different
    treatments showed that PB or DEF made mice more sensitive to
    deltamethrin (Ruzo  et al 1978b).

    Special studies in mutagenicity

    Bacteria and yeast

         In a growth inhibition test with  Escherichia coli, deltamethrin
    at levels of 1 250, 2 500 and 5 000 g/ml DMSO (0.1 ml per plate) had
    the same marginal inhibitor effect on the mother strains (W 3110 and
    WP2) as on their mutants (p 3478 and CM 611). Chloramphenicol and
    N-methyl N'-nitro-N-nitroguanidine (MNNG) were used as positive
    controls and induced clear inhibition (Peyre  et al 1980).

         Deltamethrin was compared with MNNG, 9-aminoacridine,
    2-nitrofluorene and 2-amino-anthracene for mutagenic activity in the
    Ames test with  Salmonella typhimurium, strains TA 1535, 100, 1537,
    1528 and 98. The concentrations of deltamethrin used were 2, 10, 50,
    200, 500, 1 000 and 5 000 g/plate. Deltamethrin began to precipitate
    at 200 g/plate. The mean number of revertants was not influenced by
    any concentration of deltamethrin in any strain with or without S9-mix
    (metabolic activation), whereas the positive control mutagens produced
    an increase of the number of spontaneous revertants (Peyre  et al 
    1980).

         In a similar experiment, deltamethrin (0.2, 2, 20, 200 and
    400 g/plate dissolved in DMSO) in the presence of activated
    microsomal enzymes did not influence the number of revertants of
     S. typhimurium strains TA 1535, 1537, 1538, 98 and 100.
    2-Aminoanthracene, 3-methylcholanthrene, benzo(a)pyrene and acridine
    orange showed mutagenic activity, whereas thio-TEPA was negative
    (Fouillet 1976).

         Deltamethrin at levels of 10, 50, 100, 500 and 1 000 g/plate was
    not mutagenic in assays with  S. typhimurium strains TA 1535, 1537,
    1538, 98 or 100 either in the presence or absence of a rat-liver
    homogenate metabolic activation system (the positive controls were
    2-anthramine and 9-aminoacridine) (Kavlock  et al 1979).

         Deltamethrin was not mutagenic in assays with  E. coli WP2 when
    tested at levels of 10, 50, 100, 500 and 1 000 g/plate with or
    without metabolic activation (the positive control was 2-anthramine)
    (Kavlock  et al 1979).

         Deltamethrin was not mutagenic at levels of 1 to 5% when tested
    with and without metabolic activation with  Saccharomyces cerevisiae 
    (the positive control was 1, 2,3,4-diepoxybutane) (Kavlock  et al 
    1979).

    Mammalian cells

         Deltamethrin dissolved in Cremophor oil (0, 0.4, 0.2, 1 and 5 mM,
    10, 0.08, 0.4, 2 and 10% v/v respectively) in the presence of a
    metabolic activation system increased the incidence of chromosome and
    chromatid aberrations and SCEs, after incubation with Chinese hamster
    ovary cells at 1 mMol. In the absence of S9-mix (metabolic
    activation), no higher rate of aberration was observed.

         It was shown that this increased incidence was due to a subtoxic
    effect of some reaction product of Cremaphor oil and S9-mix.
    Deltamethrin in Cremaphor oil without S9-mix and dissolved in DMSO
    (1%) at levels of 0, 0.001, 0.01, 0.1 and 0.2 mM with or without
    metabolic activation had no effect on the number of aberrations and
    SCEs. Due to insolubility, no higher concentrations were tested
    (Sobels  et al 1978).

    Animals

         Mice, 3 males and 3 females per dose, were gavaged for two
    consecutive days with 5 or 10 mg deltamethrin dissolved in sesame
    oil/kg bw. Control mice were gavaged with 0.3 ml sesame oil. The
    incidence of chromatid aberrations in bone marrow cells or of
    micronuclei in polychromic erythrocytes did not show any significant
    statistical difference in treated and control groups (Sobels  et al 
    1978).

         A single oral administration of 15 mg/kg deltamethrin was given
    to Swiss mice. Groups of 2 animals were sacrificed every 3 h during a
    24-h period. Several animals died after treatment. The incidence of
    chromatid aberrations in the femoral bone marrow was low. There was no
    consistent time-related trend in the distribution of these aberrations
    (Sobels  et al 1978).

         Deltamethrin dissolved in sesame oil in groups of 9 to 13 male
    mice dosed orally with 0 or 3 mg/kg bw for 7 days and 6 or 15 mg/kg bw
    in a single dose showed no effect on the rate of pre- or post-
    implantation losses after mating with 6 to 18 non-treated females.
    The highest dose tested was toxic to the males, e.g. 7 out of 20
    animals died shortly after treatment. Histological examination of
    the testes of all animals revealed no abnormalities. Triethylene
    thiophosphoramide (10 mg/kg bw), used as a positive control, reduced
    considerably the rate of pregnancies in the second and third week and
    increased the number of embryonal losses (Vannier and Glomot 1977).

    Special studies on humans

         Cutaneo-mucuous manifestations have been observed among plant
    workers dermally exposed to technical deltamethrin or its
    formulations. Initial lesions were tenacious and painful pruritus
    (pricking sensation), especially observed after exposure to hot water
    or on perspiration, followed by a blotchy local burning sensation with
    blotchy erythema for about 2 days. Thereafter, slight and regular
    desquamation, restricted to the contaminated area, occurred. The
    cutaneous signs are sometimes accompanied by itching of the face
    (mainly around the mouth) and/or rhinorrhoea or lacrimation. No other
    symptoms related to exposure were observed (Husson 1978).

         The effects described, which were observed before 1978 in a few
    plant workers, have not been seen since a new plant was specifically
    built for the entire automatization of deltamethrin production, which
    does not involve workers being in direct contact with intermediates
    and the final product. The only workers exposed are those involved in
    the packaging of the technical product (>98% active ingredient) and
    they are fully protected by special hermetic clothing (Glomot 1981).

         At the level of formulation plants, steps have been taken to
    avoid direct contact by workers involved in introducing technical
    powder in the basic solvent. No toxic effects have been reported in
    the past several years in these formulation plants, although a very
    limited number of workers have complained about some irritating
    effects. However, these were always transient and without any further
    consequences (Glomot 1981).

         The formulation which has been most frequently used for
    deltamethrin application is the EC. The use of both EC and ULV
    formulations corresponds in 1981 to a treated area covering several
    million hectares in the world without any case of intoxication. The
    majority of users are plant growers who apply the formulations in the
    fields and are not in contact with the technical product  per se 
    (Glomot 1981). A few cases of irritation problems have been reported
    in some workers, due primarily to the use of the EC formulation. This
    has been observed when treatments were made in orchards with high
    trees needing high volumes of mixture (e.g. in South Africa) or under
    greenhouses in confined spaces. In all cases, the reported problems
    were not severe and could be treated using antihistaminic syrups or
    with pomades based on cocaine derivatives. The irritation is most
    probably enhanced by the presence of aromatic solvent, e.g. xylene, in
    the EC formulation. Flowable experimental formulations without any
    solvent did not cause irritating effects in human volunteers (Glomot
    1981). No cases of neurological effects have been reported with
    formulation workers nor have fatal intoxications been reported (Glomot
    1981).

    RESIDUES IN FOOD

    USE PATTERN

    Pre-harvest treatments

         Information was received from The Netherlands on pre-harvest
    treatment of several crops with deltamethrin, which is summarized in
    Table 5.

    RESIDUES ARISING FROM SUPERVISED TRIALS

         Results of supervised trials with deltamethrin on various crops
    are summarized in Table 6.

    Assorted fruit, inedible peel

    Kiwi fruit

         Data from two new field trials conducted in France show that
    residue levels for the whole fruit are below 0.05 mg/kg, the residue
    being entirely in the peel.

        TABLE 5.  Deltamethrin use in The Netherlands
                                                                                     

                                   Application Rate
    Crop                          g/100 l        g/ha                 P.H.I.
                                                                                     

    Apple                         0.5                         (from before blossom to
    Pear                          0.5                         (to 14 days P.H.
    Grape                         0.5                                7
    Cherry                        0.5                                7
    Plum                          0.5                                7
    Strawberry                    0.5                                7
    Currant                       0.5                                7
    Gooseberry                    0.5                                7
    Raspberry                     0.5                                7
    Cucumber                      1.25                               3
    Melon                                        25                 14
    Bell pepper                                  25                 14
    Eggplant                                     25                 14
    Lettuce                       1.25                              14
    Endive                                       25                 14
    Radish                                        7.5                7
    Turnip                                        7.5                7
    Rutabaga                                      7.5                7
    Brussels sprouts                              7.5                7
    Cauliflower                                   7.5                7
    Broccoli                                      7.5                7
    Kohlrabi                                      7.5                7
    Leek                                          7.5                7
    Onion                                         7.5                7
    Peas                                          7.5                7
    Dwarf french bean                             7.5                7
    Sugarbeet                                     7.5                7
    Mushroom                      0.75-1.5        75/100             2
                                                                                     
    
    Hops

         Several trials conducted in the UK and the Federal Republic of
    Germany show a high level of variation between samples, but relatively
    little decline with time over the period of 7 to 14 days following
    treatment. No information was provided on the fate of such residues
    when the hops were used in brewing.

        TABLE 6.  Supervised trials with deltamethrin in various crops
                                                                                                                                                
                                                  Application                                Residues (mg/kg) at intervals(days) after application
                                                                                                                                                
    Crop           Country        Year      No.  Rate                       Part
                                                 (g a.i./ha)  Formulation   of sample         0        1        2/3      4        7        14
                                                                                                                                                
    Kiwi fruit     France         1980      2    12.5                       peel              0.05              0.06     0.06     0.08     0.07
                                                                            whole fruit       0.01              0.01     0.01     0.01     0.01
                                                                            pulp              ND                ND       ND       ND       ND
                                                 12.5                       peel              0.4               0.22     0.23     0.25     0.1
                                                                            whole fruit       0.06              0.04     0.04     0.04     0.01
                                                                            pulp              ND                ND       ND       ND       ND

    Hops           England        1978      7    12.5                                                                    0.02
                   W. Germany     1978      1    25                                                             0.01

                                            3    62.5                                         0.1               0.3      1.4      1.1      1.9
                                            3    62.5                                         16                5.5      0.1      1.8      1.9
                                            3    62.5                                         3.3               1.3      0.4      2.0      2.5

                                  1980      5    6.25-37.5                                    1.3               0.2      0.4      0.3      0.7
                                            5    "                                            0.2               0.7      0.3      0.7      1.6
                                            5    "                                            1.0               0.7      0.2      0.6      2.7
                                            5    "                                            0.5               0.3      0.2      0.7      1.1

    Mushrooms1     Netherlands    1978      2    6.25         0.0025%       whole                      0.003    0.002    0.001
                                  1978      2    25           0.01%         "                          0.009    0.004    0.003

                                                                                                                 (DAYS)
                                                                                              0        1        3        5        7        14
                                                                                                                                                
    Black currant  Finland        1979      1    6.3mg/bush.                                                                      0.1      0.1
                   W. Germany     1979      2    18.5g/ha                                     0.3               0.2      0.2      0.1
                                                 "                                            0.3               0.3      0.3      0.3
                                                 "                                            0.3               0.2      0.2      0.2
                                            2    11.25g/ha                                    0.2               0.2      0.1      0.1
                                                                                              0.3               0.4      0.3      0.2
                                                                                                                                                

    TABLE 6.  (con't)
                                                                                                                                                

                                                  Application                                Residues (mg/kg) at intervals(days) after application
                                                                                                                                                
    Crop           Country        Year      No.  Rate         Part
                                                 (g a.i./ha)  of sample                     0    1     2      4        8          14       21
                                                                                                                                                

    Spinach        France         1978      1    17.5g/ha     Fresh leaf                               0.48   0.33     0.22
                                                              Cooked leaf                                     0.27     0.21
                                                              Cooking water                                   0.0001   0.00009
                                                 17.5g/ha     Fresh leaf                               0.52   0.30     0.155
                                                              Cooked leaf                                     0.28     0.12
                                                              Cooking water                                   0.00015  0.000,05
                                  1979      1    12.5g/ha     Fresh leaf                               0.4    0.2      0.14       0.12
                                                              Cooked leaf                                              0.12       0.10
                                                              Cooking water                                            0.0001     ND
                                                 12.5g/ha     Fresh leaf                               0.4    0.2      0.17       0.15
                                                              Cooked leaf                                              0.15       0.12
                                                              Cooking water                                            0.00015    0.0001
                                  1980      1    17.5g/ha     Fresh leaf                               0.18   0.22     0.35
                                                              Cooked leaf                              0.16   0.20     0.28
                                                              Cooking water                            ND     ND       ND
                   W.Germany      1980      3    12.5g/ha     Fresh leaf                    0.3        0.7    0.2      0.09
                                                                                            0.7        0.3    0.3      0.1

                                                                                            14   21    28/39  49       61         74       80
    Wheat straw    France         1978      1    7.5          EC                                                                           0.015
                                            1    15           EC                                                                           0.05
                                            1    7.5          EC                                                                  0.025
                                            1    15           EC                                                                  0.025
                                            1    7.5          EC                                                                  0.025
                                            1    15           EC                                                                  0.025
                                            1    7.5          EC                                                                  ND
                                            1    7.5          EC                                                                  ND
                                            1    12.5         EC                                       0.15
                                            1    12.5         EC                                       0.06
                                            1    12.5         EC                                       0.2
                                            1    12.5         EC                                       0.1
                                                                                                                                                

    TABLE 6.  (con't)
                                                                                                                                                

                                                  Application                                Residues (mg/kg) at intervals(days) after application
                                                                                                                                                
    Crop           Country        Year      No.  Rate         Part
                                                 (g a.i./ha)  of sample                     14   21    28/39  49       61         74       80
                                                                                                                                                

    Oat Straw      W.Germany      1978      1    12.5         EC                                       0.06
                                            1    12.5         EC                                       0.06
                                            1    12.5         EC                                       ND
                                            1    12.5         EC                                       0.08
                                  1979      1    12.5         EC                                       0.6
                                            1    12.5                                                  0.2
                                            1    12.5                                                  0.2
                                            1    12.5                                                  0.5

    Rice straw     Surinam        1977      1    6.25                                                         ND
                                            1    12.5                                                         0.010
                                            1    18.75                                                        0.01
                                            1    25                                                           0.08

                   Phillipines    1978      1    17.5                                                  0.2
                                                 25                                                    0.1
                                                                                                                                                

    1  After oven drying at 7 days.
        Small fruits and berries

    Black currant

         From trials conducted in the Federal Republic of Germany, it
    would appear that residues on these berries can range up to 0.3 to
    0.4 mg/kg, but as yet, there is no registered use of deltamethrin on
    black currants.

    Leafy vegetables

    Spinach

         Additional data from trials carried out in France and the Federal
    Republic of Germany indicate that residues range around 0.3 to
    0.4 mg/kg, 7 or 8 days after the last treatment. These levels do not
    decline significantly during cooking.

    Fodder and cereal straws

         Additional data were available to indicate the level of
    deltamethrin on wheat straw, oat straw and rice straw. Though the bulk
    of the values were below 0.2 mg/kg, oat straw sampled 28 to 39 days
    after treatment showed residues ranging up to 0.6 mg/kg. The amount of
    data is, however, limited and in view of the potential for the wide
    application of deltamethrin to cereal crops further data are required.

    Cereal grains

         A report was received on trials to determine the fate of
    deltamethrin on wheat during storage and after milling and baking
    (Halls and Periam 1980).

         Batches of an English hard wheat were sprayed on a conveyor with
    diluted deltamethrin/piperonyl butoxide liquid grain protectant to
    give 250 kg at each of two deltamethrin treatment levels. These 250 kg
    batches were then placed in 1 ton capacity metal silos. Target
    treatment levels for the two batches of grain were 1 mg/kg
    deltamethrin + 10 mg/kg piperonyl butoxide and 2 mg/kg deltamethrin +
    10 mg/kg piperonyl butoxide respectively, but chemical analysis
    revealed that the actual treatment levels achieved were only about 40
    to 75% of these.

         Samples of the treated wheat were taken after spraying and
    thereafter at monthly intervals for nine months and analysed for
    deltamethrin content. Replicate samples were taken from each silo,
    analysed separately and the result expressed as the mean. Wheat from
    the initial sampling and from samplings after 3, 6 and 9 months was
    submitted to the Flour Milling and Baking Research Association,
    Chorleywood, Buckinghamshire to be milled and baked.

         At Chorleywood the wheat was first cleaned of extraneous
    material, then divided into two samples and each subjected to a
    different milling procedure. The first produced whole-meal flour, the
    second produced white flour, bran and fine offal.

         Two different samples of white flour were taken from this
    procedure, the first reduction flour (the cleanest flour mainly from
    the centre of the grain and used in the baking of cakes) and total
    white flour (straight-run flour plus flour from the bran and fine
    offal fractions). These samples, together with the wholemeal flour,
    bran and fine offal were analysed for total deltamethrin content for
    both batches of treated wheat. In addition, bread was baked from both
    wholemeal and total white flours to produce wholemeal and white bread,
    respectively, and these loaves were also analysed for deltamethrin
    content.

         Results for residues of deltamethrin on wheat, milling data and
    residues of NRDC 161 on flour fractions and bread are given in Tables
    7, 8 and 9, respectively.

         In both the deltamethrin treatments, levels were initially found
    by analysis to be only about 40% of the expected application. This
    could be due predominantly to  inter alia incorrect spraying rates,
    inadequate extraction, or loss of compound at some stage between the
    nozzle and the grain.

         The results given in Table 7 show that for both application rates
    there was no detectable breakdown of deltamethrin on wheat over a
    nine-month storage period. The fluctuation in levels between different
    samplings was within the inherent error of the analytical method
    demonstrating that deltamethrin is very stable on wheat. In this
    respect deltamethrin differs from many organophosphate grain
    protectants such as fenitrothion (Desmarchelier 1978).

         The moisture content of the wheat remained fairly consistent over
    the storage period of nine months. Deltamethrin analysis data for the
    milling fractions and bread derived from treated wheat are given in
    Tables 8 and 9.

         For all sampling times at both treatment levels there was no
    significant change in deltamethrin residues when wheat was milled to
    produce wholemeal flour. When this flour was baked, the wholemeal
    bread produced contained lower, or identical, deltamethrin residues
    but this can be explained by the greater moisture content (up to 45%)
    present in bread.

        TABLE 7.  Deltamethrin residues on wheat after indicated periods of storage in the UK1
                                                                                                                                                

                                                    Residue analysis (mg/kg deltamethrin)
    Target                                                                                                                                      
    Application    Initial2     1 month      2 months     3 months     4 months     5 months     6 months     7 months     8 months     9 months
    rate (mg/kg)   (15.11.79)   (13.12.79)   (17.1.80)    (11.2.80)    (12.3.80)    (21.4.80)    (12.5.80)    (10.6.80)    (10.7.80)    (6.8.80)
                                                                                                                                                

    1.0            0.44         0.53         0.48         0.50         0.50         0.41         0.48         0.49         0.42         0.41

    2.0            0.80         1.25         1.33         1.46         1.21         1.01         0.96         1.12         0.94         1.08
                                                                                                                                                

    1  Analytical results are subject to overall confidence limits of 30%

    2  Dates refer to day of sampling.

    TABLE 8.  Milling data for wheat freshly treated with deltamethrin and from wheat after 3, 6 and 9 months storage1
                                                                                                                                       

    Target application   Sampling    Clean wheat               Bran                      Fine Offal               Total white flour
    rate                 period                                                                                                        
    (mg/kg)              (months)    Weight       Prop. of     Weight      Prop. of      Weight       Prop. of    Weight      Prop. of
                                     (kg)         total(%)     (kg)        total (%)     (kg)         total (%)   (kg)        total (%)
                                                                                                                                       

                         0           3.835        100          0.596       15.54         0.306        7.98        2.849       74.29

                         3           4.921        100          0.779       15.83         0.519        10.55       3.502       71.16

    1.0
                         6           3.700        100          0.621       16.78         0.340        9.19        2.670       72.16

                         9           3.700        100          0.626       16.92         0.288        7.78        2.746       74.22
                                                                                                                                       

                         0           3.786        100          0.590       15.58         0.292        7.71        2.809       74.19

                         3           4.884        100          0.769       15.75         0.514        10.52       3.489       71.44

    2.0

                         6           3.700        100          0.630       17.03         0.306        8.27        2.688       72.65

                         9           3.700        100          0.650       17.57         0.275        7.43        2.692       72.76
                                                                                                                                       

    0 (Control)          0           2.010        100          0.312       15.52         0.175        8.71        1.525       75.87
                                                                                                                                       

    1  There is a loss of up to 3% in the laboratory milling process

    TABLE 9.  Deltamethrin residues on milling fractions and bread made from freshly treated wheat and from wheat after 3, 6 and 
              9 months storage1
                                                                                                                                       

    Target application   Sampling                                                                  First          Total
    rate                 period                   Wholemeal    Wholemeal   Bran     Fine           reduction      white           White
    (mg/kg)              (months)    Wheat        flour        bread                offal          flour          flour           bread
                                                                                                                                       

                         0           0.44         0.42         0.26        3.00     nd2            nd             0.09            0.10

                         3           0.50         0.43         0.27        1.80     approx. 0.5    nd             approx. 0.05    nd

    1.0
                         6           0.48         0.42         0.26        1.70     0.35           0.05           0.09            0.10

                         9           0.41         0.36         0.36        1.90     0.46           0.03           0.03            0.05
                                                                                                                                       

                         0           0.80         0.73         0.63        5.40     nd             nd             0.20            0.29

                         3           1.46         0.80         0.57        4.70     0.75           nd             0.20            0.15

    2.0
                         6           0.96         0.83         0.66        3.60     0.75           0.10           0.16            0.20

                         9           1.08         0.95         0.70        4.40     1.36           0.05           0.17            0.11
                                                                                                                                       

    1  Analytical results are subject to confidence limits of  30%
    2  nd = not detectable (<0.03 mg/kg).
             When the treated wheats were milled to produce white flour,
    relatively high deltamethrin residues were found on the bran fraction,
    which is derived from the superficial layers of the grain. Initially,
    deltamethrin residues on the bran were 6 to 7 times higher than those
    on the wheat at both treatment rates. The levels declined to be about
    4 to 5 times higher on the bran than on the wheat after 9 months'
    storage.

         This observation, together with the appearance of deltamethrin on
    the fine offal fractions after 3 months' storage, and on the first-
    reduction flours after 6 months' storage, suggests that although there
    is no change in the total deltamethrin level on the wheat over 9
    months, there is a subtle change in its distribution. Thus, initially,
    as might be expected, the insecticide residues were found
    predominantly in the outer layers of the grain, mainly in the bran
    fraction, but also to a lesser extent in the total white flour
    fraction. The first-reduction flour, which tends not to come from the
    superficial layers of the grain, and the fine offal, consisting
    largely of wheatgerm, is uncontaminated initially but residues move
    into these areas as the period of storage is increased.

         The deltamethrin levels on total white flour milled from treated
    wheat after different storage periods remained quite constant at about
    one sixth of the applied rates. Some fluctuation in this proportion
    was detectable at the lower application rate, but this is probably
    because in these cases the deltamethrin levels on the flour were close
    to the limits of detection. When baked in white bread, there is no
    significant change in residue levels, showing that no breakdown of
    deltamethrin occurred during baking.

         Consideration of the levels found on each fraction, and the
    weights of each fraction produced by unit weight of wheat, leads to
    the conclusion that there is no breakdown of deltamethrin during the
    break, reduction and finishing systems of the milling process that
    produces white flour.

         The following conclusions may be drawn from the results of this
    trial:

         Deltamethrin is not degraded on wheat over a nine-month storage
    period.

    There is no degradation of deltamethrin when treated wheat is milled
    to produce either wholemeal or white flour.

    When wholemeal flour made from deltamethrin treated wheat is baked,
    there is an apparent reduction in deltamethrin residues, but this is
    due to the greater moisture content of the bread.

    In the production of white flour and bread from deltamethrin treated
    wheat, there is a reduction in the deltamethrin level to about 10 to
    20% of the level applied to the wheat. This is because the
    deltamethrin is predominantly found on the bran fraction with a
    concentration increase of 4 to 7 fold. There is no evidence for
    deltamethrin degradation when white flour is baked to produce white
    bread.

    Over a 9-month storage period, there appears to be a migration of
    deltamethrin to the fine offal fraction (including the wheat germ
    which is used in health foods and "Hovis" bread) and the first-
    reduction flour (used in the production of cakes) presumably from the
    bran fraction (predominantly used for animal feed).

    NATIONAL MAXIMUM RESIDUE LIMITS

    The Meeting was advised of the following limits established by The
    Netherlands:

    Strawberry               0.2 mg/kg
    Other fruit              0.1 mg/kg
    Leafy vegetables         0.2 mg/kg
    Other vegetables         0.05 mg/kg

    EVALUATION

    COMMENTS AND APPRAISAL

         Deltamethrin was first evaluated in 1980 but, in the absence of
    some essential toxicological information, it was not possible to
    establish an ADI. The Meeting proposed a series of guideline levels
    reflecting residues likely to occur on various food commodities
    following the use of deltamethrin with present good agricultural
    practice. A small amount of additional information was available for
    consideration at the Meeting.

         Residue data from trials on kiwi fruit were considered suitable
    to propose guideline levels, but further data are needed to confirm
    whether these levels are typical of those occurring in other regions
    where these crops are grown. In the case of kiwi fruit, the residues
    are entirely confined to the inedible peel. Data were received from
    residue trials on black currants, but as there was evidence that
    deltamethrin was not yet approved for use on currants, no guideline
    levels were proposed.

         Results of several trials on spinach indicate that cooking has
    little or no effect on the level of deltamethrin residues on such
    leafy vegetables. These studies do not, however, provide an adequate
    basis for determining whether the guidelines proposed in 1980 for
    spinach should be amended.

         There is a suggestion that residues of deltamethrin on some
    cereal straws used for animal feed could be higher than the 0.5 mg/kg
    limit proposed for legume animal feeds, but the amount of information
    is inadequate to provide a basis for amending the recommendation.

         A report on one further study of the level and fat of
    deltamethrin on wheat, milled products and bread confirm that
    deltamethrin is not degraded significantly during storage, nor is it
    destroyed in cooking. A substantial proportion is, however, removed on
    bran during the milling of white flour. In view of the vast experience
    with other grain protectant insecticides and the considerations
    discussed in 1980, the Meeting deemed it necessary to revise the
    recommended guideline levels for deltamethrin on raw cereals and
    milled cereal products to accommodate, realistically, all the
    situations likely to arise from normal applications under good storage
    practice, although in most cases, levels would be considerably lower.
    Such provisions are also intended to accommodate the variations due to
    sampling difficulties and analytical error.

         The Meeting, however, expressed the view that considerably more
    information was required about the level and fate of deltamethrin on
    different grains under different storage conditions and especially the
    effect of processing and cooking of all cereal grains.

    RECOMMENDATIONS OF GUIDELINE LEVELS

         As no ADI has been allocated, the Meeting proposed the following
    guideline levels determined and expressed as deltamethrin.

    Commodity                          Guideline level (mg/kg)
                                                              

    Kiwi fruit                                  0.05

    Hops (dry)                                  5

    Cereal straw (animal feed)                  0.5

    Cereal grains                               2

    Wheat bran (unprocessed)                    5

    Wheat flour (wholemeal)                     2

    FURTHER WORK OR INFORMATION

    Required (by 1982 and before an acceptable daily intake can be
    allocated) (as listed in the 1980 JMPR Report).

    1.   Results of the two-year feeding study in dogs currently in
         progress.

    2.   Clarification of possible embryotoxic effects in animals.

    3.   Further observations on reported effects in man.

    4. Studies on the significance of neurological effects observed in
    several animal species.

    5.   Results of supervised trials on residues in meat, milk, and eggs
    arising from the use of deltamethrin for ectoparasite control, in
    feeding studies and in stable treatments. Also required before MRLs
    can be recommended:

    6.   Considerably more information on the level and fate of
    deltamethrin on various cereal grains treated under different storage
    conditions, and especially the effect of processing and cooking of all
    cereal grains.

    7.  Additional residue data from supervised trials on kiwi fruit,
    currants and leafy vegetables.

    8.  Information on the level and fate of deltamethrin residues in
    foods of animal origin following the feeding of cattle, pigs and
    poultry with rations containing deltamethrin at levels of the order
    likely to be encountered in practice.

    9.  Further information on the level of deltamethrin on cereal grains
    following treatment of crops in conformity with approved or proposed
    use patterns.

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    See Also:
       Toxicological Abbreviations
       Deltamethrin (EHC 97, 1990)
       Deltamethrin (HSG 30, 1989)
       Deltamethrin (ICSC)
       DELTAMETHRIN (JECFA Evaluation)
       Deltamethrin (Pesticide residues in food: 1980 evaluations)
       Deltamethrin (Pesticide residues in food: 1982 evaluations)
       Deltamethrin (Pesticide residues in food: 1984 evaluations)
       Deltamethrin (JMPR Evaluations 2000 Part II Toxicological)
       Deltamethrin (UKPID)
       Deltamethrin (IARC Summary & Evaluation, Volume 53, 1991)