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    CARBARYL      JMPR 1977

    Explanation

    When carbaryl was last reviewed in 1976 (FAO/WHO, 1977b) the use and
    fate on stored grain were evaluated in the light of extensive
    information and maximum residue limits were recommended for carbaryl
    on barley, oats, rice, rye and wheat.

    Information has since become available on the level and fate of
    carbaryl following its use on stored sorghum, together with further
    data on the rate of disappearance of carbaryl on stored raw cereals
    generally. The following monograph addendum summarises that
    information.

    RESIDUES IN FOOD AND THEIR EVALUATION

    RESIDUES RESULTING FROM SUPERVISED TRIALS

    The use of carbaryl for the control of Rhyzoperta domenica which
    is not sufficiently sensitive to organophosphorus insecticides to be
    controlled effectively by approved grain protectant insecticides
    including malathion, dichlorvos, fenitrothion, clorpyrifos-methyl,
    bromophos and pirimiphos-methyl was referred to in the 1976 monograph
    (FAO/WHO, 1977b). Bengston at al. (1977a) have reported the results of
    commercial-scale trials in which carbaryl was applied at the rate of 6
    mg/kg in conjunction with pirimiphos-methyl at 4 mg/kg to 18 silos
    each holding approximately 2000 tons of wheat. Table 1 gives the
    results obtained by analyzing samples of grain drawn at intervals
    (generally monthly) over periods up to 9 months. The average grain
    temperature over the storage period ranged from 22 to 30 C and
    average relative humidity in the inter-grain space calculated from
    grain moisture (9-11%) ranged from 35 to 49%. The residue data were
    used to calculate the half-life of the deposit which was found to
    range from 22 to 50 weeks.

    Bengston at al. (1977b) report the outcome of extensive experiments
    with a range of grain protectants for the control of
    malathion-resistant insects in stored sorghum. Carbaryl applied at a
    nominal rate of 8 mg/kg controlled Rhyzopertha domenica for more
    than 24 weeks (work still in progress). Table 2 indicates the level of
    carbaryl residues in samples of sorghum dram from treated silos and
    analysed by the method of Desmarchelier (1977a).

    Desmarchelier (1977b) has measured the rate of loss of carbaryl
    residues under 12 fixed sets of laboratory conditions and has derived
    a general model relating the half-life to temperature and relative
    humidity. The model is indicated in a graph which is reproduced as
    Figure 1. From this model it is possible to predict the residue level
    after any interval of storage from a knowledge of temperature and the
    relative humidity of the intergrain space and thus to determine the
    rate of application required to provide the requisite level of
    protection for the anticipated period of storage. Application of the

    FIGURE 1



        TABLE 1. Residues of carbaryl in stored wheat 1976-77 Pilot studies (Australia) ( from Bengston et al., 1977a)
                                                                                                                            
    Site      Bin
              No.       Dec.      Jan.      Feb.      Mar.      Apr.      May       June      July      Aug.      Sept.
                                                                                                                            
    1         8         3-5       5-6       4-6       4-6       2-4       2-4       2-4                 2-4       2-4
    2         1         1-2                 -         1-2
    3         8         2-4       -
    4         8         3-5       5-6       2-4       2-4                 1.5-3     1-2
    5                             8-10                6-8                           6-8
    6         93*       3-5       3-5       3-5                 2-4       1-2                           1.5-3
    "         98        3-5       3-5       3-5                 2-4       1-2       1-2                 1.5-3
    "         99                  2-4       3-5                 2-4       2-4       2-3                 2-4
    7         1-3                           6-8       4-6                 4-6       4-6                 4-6       4-6
    "         2-3                           5-7       5-7                 4-6       3-5                 4-6       3-5
    "         3-3                           4-6       4-6                 4-6       3-5                 2-4       2-4
    8                                                 4-6                 2-4       2-4                 1.5-3     1.5-3
    9                                                 5-7                 3-5       -                   4-6
    10                                                5-7                 4-6       3-5                 2-4       2-4
    11        19                                                          4-6       2-4                 1.5-3
    12                                                                    4-6       2-4                 2-4       2-4
    13                                                                    4-6       4-6                 2-4       2-4
    14                          5 samples, April-May: 1-2, 2-4, 4-6, 5-7, 5-7       4-6                           4-6
                                                                                                                            

    * Aerated

    TABLE 2. Residues of carbaryl in sorghum stored in bulk silos stored at various times prior to assay (Bengston et al., 1977b)
                                                                                                                            
    Site      Grain      Average     Application                   Residue, mg/kg, at week
              Temp.      Moisture    Rate mg/kg      1         4         8       12        18          24
                                                                                                                            
    1         26C       12.4%       8.7             6-8       4-6       3-5     2-4       1.5-3       0.6-.08
    2         27C       12.2%       7.8             2-4       4-6       -       1.5-3     0.75-1.5    0.4-0.6
                                                                                                                            
    


    model to extensive field trial data on wheat, barley and sorghum has
    confirmed the practical validity of the prediction. The use of this
    model should enable residue levels to be maintained as low as possible
    consistent with obtaining adequate insect control.

    The new information indicates that the maximum residue limit
    recommended previously for carbaryl on sorghum from pre-harvest use is
    appropriate to cover residues resulting from post-harvest application.

    FURTHER WORK OR INFORMATION

    Desirable

    See Report of 1976 Meeting (FAO/WHO, 1977a, p. 29)

    NOTE.

    In the Report of the 1977 Meeting (FAO/WHO, 1978a, Annex 1), the
    recommended maximum residue limit for carbaryl in meat of cattle,
    goats and sheep is recorded both as 1 mg/kg and 0.2 mg/kg. The correct
    limit is 0.2 mg/kg; the recommendation was lowered from 1 to 0.2 mg/kg
    by the 1973 Meeting. A correction will be published in Annex 1 of the
    Report of the 1978 Meeting.

    REFERENCES

    Bengston, M., Connell, M., Desmarchelier, J., Phillips, M., Ridley,
    E., Ripp, B., Snelson, J. and Sticka, R. (1977a) Report of pilot-scale
    studies of grain protectants on wheat. Report to Australian Wheat
    Board, July 1977 (to be published).

    Bengston, M., Cooper, L.M., Davies, R.A.H., Desmarchelier, J.M., Hart,
    R.J. and Phillips, M. (1977b) Grain protectants for the control of
    malathion-resistant insects in sorghum J. Stored Prod. Res. (in
    press).

    Desmarchelier, J.M. (1977a) Simultaneous clean-up and esterification
    of phenols, at residue levels, by reaction with anhydrides in dilute
    base. Residue Vol. 4 (in press).

    Desmarchelier, J.M. (1977b) (CSIRO Division of Entomology, Canberra)
    Loss of carbaryl on grains in storage (in press).

    FAO/WHO (1977a) Pesticide residues in food. Report of the 1976 Joint
    Meeting of the FAO Working Party of Experts on Pesticide Residues and
    the WHO Expert Committee on Pesticide Residues. FAO Plant Production
    and Protection Series No. 8; WHO Technical Report Series No. 612.

    FAO/WHO (1977b) 1976 evaluations of some pesticide residues in food.
    FAO/AGP:1977/M/5.
    


    See Also:
       Toxicological Abbreviations
       Carbaryl (EHC 153, 1994)
       Carbaryl (HSG 78, 1993)
       Carbaryl (ICSC)
       Carbaryl (PIM 147)
       Carbaryl (FAO Meeting Report PL/1965/10/1)
       Carbaryl (FAO/PL:CP/15)
       Carbaryl (FAO/PL:1967/M/11/1)
       Carbaryl (FAO/PL:1968/M/9/1)
       Carbaryl (FAO/PL:1969/M/17/1)
       Carbaryl (AGP:1970/M/12/1)
       Carbaryl (WHO Pesticide Residues Series 3)
       Carbaryl (WHO Pesticide Residues Series 5)
       Carbaryl (Pesticide residues in food: 1976 evaluations)
       Carbaryl (Pesticide residues in food: 1979 evaluations)
       Carbaryl (Pesticide residues in food: 1984 evaluations)
       Carbaryl (Pesticide residues in food: 1996 evaluations Part II Toxicological)
       Carbaryl (JMPR Evaluations 2001 Part II Toxicological)
       Carbaryl (IARC Summary & Evaluation, Volume 12, 1976)