Sponsored jointly by FAO and WHO


    Joint meeting of the
    FAO Panel of Experts on Pesticide Residues
    in Food and the Environment
    and the
    WHO Expert Group on Pesticide Residues
    Geneva, 3-12 December 1979



    Pirimicarb was evaluated at the 1976 and 1978 Meetings when MRLs were
    recommended for an extensive list, predominantly of fruit and
    vegetables, and a temporary ADI was established.  The only outstanding
    queries related to the need for a carcinogenic study, to be completed
    in time for the 1980 Meeting.

    At the 11th Session of the CCPR, a suggestion was made that the MRL of
    0.5 mg/kg for "beans with pod", which was proposed by the 1976
    Meeting, should be increased to 1 mg/kg.  Information on the use of
    pirimicarb on beans together with the results of supervised trials
    supporting an increase in the MRL is reviewed in the present monograph



    Pirimicarb is normally effective at rates of 125-250 g/ha, depending
    upon the circumstances.  The higher rate will tend to be needed under
    the conditions of heaviest aphid infestation or to kill some species.
    At the time of the 1976 Meeting, a preharvest interval (PHI) of 7 days
    was typical for crops such as dwarf or runner beans.  The 1976 Meeting
    proposed the limit of 0.5 mg/kg for "beans in pod", notwithstanding
    the existence of an occasional value up to 0.55 mg/kg 7-8 days after
    spraying at 250 g/ha.

    Since 1976, there has been a trend towards a shorter PHI and, for
    example, a 3-day PHI has been cleared on this crop in the United
    Kingdom.  In many respects, this is most appropriate to the behaviour
    of residues of the compound, since these have been shown to decline
    rapidly during the first 2-3 days after spraying (volatilization being
    an important means of loss) and then more slowly.


    The available data for the 250 g/ha rate and a 3-day PHI, provides
    justification for increasing the MRL to 1 mg/kg.

    Manley (1972) in a summary of information on pirimicarb residues in
    crops, points out that trials carried with the 50% dispersable powder
    and the 5% emulsifiable concentrate formulations applied to French
    beans using a hand lance and boom sprayer indicated that residues
    following application by boom sprayer were considerably less than
    those following application by lance.  However, later results did not
    endorse this pattern, and some other cause must be responsible for the
    variations in residue levels.

    Table 1. Pirimicarb Residues in French Beans - Summary of Results
             from U.K. 1968-71

                                 No. of samples
    Application   Days between   analysed with       Total carbamate
       rate       application      residues          residues (ppm)
    g a.i./l      and harvest    >0.06    <0.06       Range       Mean
                                 ppm      ppm

    0.25             0            3        2       <0.06-0.95     0.44
                     4            6        7       <0.06-0.63     0.23
                    7-8           6        4       <0.06-0.55     0.24
                   13-14         11        1       <0.06-0.57     0.30

    0.50             0            3        0        0.89-1.4      1.1
                     4            9        4       <0.06-0.95     0.39
                    7-8           7        4       <0.06-0.67     0.30
                   13-14         11        1       <0.06-0.69     0.40

    Table 2. Pirimicarb Residues in Runner Beans - Summary of results from
             Germany 1973/75

    Application    Interval       No. of samples    Total carbamate
    rate           between        analysed with        residues
    (kg ai/ha)     application    residues              (ppm)
                   and harvest    >0.01     <0.01     Range      Mean
                   (days)         ppm       ppm

    0.3                0            1         0                  0.74
                       1            1         0                  0.18
                       2            1         0                  0.18
                       3            1         0                  (1.3)*
                       4            1         0                  0.07
                       7            1         0                  0.05
                       10           1         0                  0.01

    0.5                0            3         0      0.03-0.18   0.12
                       1            3         0      0.07-0.15   0.12
                       3            3         0      0.06-0.10   0.08
                       5            3         0      0.03-0.07   0.06
                       7            3         0      0.02-0.06   0.05
                       10           2         0      0.01-0.05   0.03

    * Suspect result

    The results obtained in a number of trials over the period 1968-71 are
    summarized in Table 1.  Total carbamate residues declined rapidly
    during the first few days after spraying and then more slowly.  This
    is consistent with the pattern already seen on other vegetables
    (FAO/WHO 1977b).

    Edwards and Dick (1976) in a summary of reports of residue trials in
    crops during 1973/75, record that in four trials in Germany pirimicarb
    was sprayed on beans at the rate of 0.3-0.5 kg/ha and 600-1000 L/ha.
    The results are summarised in Table 2.  Examination of the three
    trials where pirimicarb was applied at the rate of 0.5 kg/ha showed
    lower initial residues to be present (0.12 mg/kg at 0 days).  These
    residues degraded slowly to 0.03 mg/kg at 10 days.  A single trial
    where pirimicarb was applied at the rate of 0.3 kg/ha gave a higher
    initial residue of 0.74 mg/kg which degraded more rapidly to 0.01
    mg/kg at 10 days.

    The samples from the German trials were analysed by a
    gas-chromatographic procedure with a limit of determination of 0.01


    At the request of the 11th Session of the Codex Committee on Pesticide
    Residues the meeting re-evaluated pirimicarb residues on "beans with
    pod" in the light of data from the 1976 Monographs and detailed
    reports from the manufacturers.  In the light of amended use patterns
    which involve a shorter pre-harvest interval, the meeting agreed that
    the MRL should be raised from 0.5 to 1 mg/kg.


    The recommended maximum residue limits for pirimicarb should be
    amended as follows:

    Commodity          Temporary maximum      Pre-harvest interval on
                         residue limit        which the recommendation
                            (mg/kg)                  was based

    Beans (with pod)           1                       3 days


    Edwards, M.J. and Dick, J.P. - Pirimicarb Residue Summary: Residues in
    crops from Field Trials during 1973-75".  ICI Plant Protection
    Division Report No. TMJ1360B (1976), Unpublished.

    Manley, C.A. - Residue Summary: Pirimicarb in Crops". ICI Plant
    Protection Limited Report No. TMJ585/2 (1972), unpublished.

    See Also:
       Toxicological Abbreviations
       Pirimicarb (Pesticide residues in food: 1976 evaluations)
       Pirimicarb (Pesticide residues in food: 1978 evaluations)
       Pirimicarb (Pesticide residues in food: 1981 evaluations)
       Pirimicarb (Pesticide residues in food: 1982 evaluations)