Carbophenothion was evaluated at the 1972 JMPR (FAO/WHO 1973).
    Temporary tolerances were recommended for various fruits, nuts,
    vegetables, meat (fat), milk (fat), and olive oil. The tolerances
    are expressed as carbophenothion but apply to total residues
    including parent, its sulfoxide and sulfone and their corresponding
    oxygen analogs. Further work on plasma cholinesterase depression
    and a reproduction study were required for evaluation by the 1976
    Joint Meeting. At the 1975 (Eighth) Session of the Codex Committee
    on Pesticide Residues, the delegation of the Netherlands requested
    re-evaluation of carbophenothion by the 1976 Joint Meeting.


         Since the additional data required by the 1972 Joint Meeting
    were not available and there was no indication of intent to provide
    these data, the previously allocated temporary ADI was withdrawn.


         Country statements for the 1976 Joint Meeting were received
    from Australia, the Netherlands, and the United Kingdom. The
    information provided on current national uses of carbophenothion
    did not indicate a need for additional maximum residue limits for
    crops beyond those recommended by the 1972 Meeting. No additional
    data from supervised residue trials were available. The country
    statements included some information of interest on current use
    patterns, national tolerances and residue chemistry.


         Information provided by the responding countries on current
    use patterns are shown in Table 1.


         A submission from the United Kingdom reported research
    relating to injury to geese from the use of carbophenothion as a
    seed dressing on cereals. This use was subsequently withdrawn from
    certain areas in the U.K. The report included some collateral
    studies which were of interest with regard to possible residues in
    human foods. Carbophenothion and four esterase inhibiting
    degradation products were found at significant levels within the
    roots and bulbs of wheat grown from treated seeds, suggesting that
    carbophenothion has some systemic activity. Residues in the leaves
    were, however, very low. The identified inhibitors were
    carbophenothion sulphone, carbophenothion sulphoxide and the
    corresponding oxygen analogue and oxygen analogue sulphone. (Brown
    and Torpey, 1976).

    TABLE 1. National use patterns of carbophenothion

                                        Application          interval          National(1)
    Country          Crop               Rate                 (days)            tolerances (mg/kg)

    Australia        fruits             0.05% emul. spray    21                1
                     vegetables         2 kg/ha              21                1

                     cattle, sheep      0.1% emul. spray     14(pre-           1 (fat basis)

                     pasture, forage    0.05% emul. spray    7(cutting or      0.1 milk and(2)
                                                             grazing)          milk products

    Netherlands      prunes, peaches    14.75%               before bloom      0.01(2)
                     grapes             aerosol              and after
                     (under glass)      0.06 g/m3            harvest

    (1)  Maximum residue limits or tolerances as reported to the 1976 meeting.

    (2)  Tolerance represents a change from national tolerances listed in 1972
         monograph (FAO/WHO, 1973b).


         A laboratory experiment in the same report disclosed photolysis
    products after exposure to sunlight and UV radiation. In addition to
    the alteration products found in wheat seedlings, carbophenothion oxon
    and the insecticide ethion were identified after 130 hours' exposure
    to sunlight. (Machin et al., 1976). UV radiation at 254 nm produced
    four other related organophosphorus products. The experiments did not
    show whether, under field conditions, any of these compounds would
    constitute a significant part of the terminal residue on crops.


         A comprehensive discussion of the methods available for
    carbophenothion and its oxidative metabolite residues in foods appears
    in the 1972 evaluation of this pesticide (FAO/WHO 1973b).

         Certain advances in carbophenothion methodology were called to
    the attention of the 1976 meeting. Jennings et al. (1975) describe
    an improved method for carbophenothion in avian tissues in which
    extraction with diethyl ether is followed by an alumina column
    clean-up. Alternative determinative steps specified in this method are
    TLC, GC with flame photometric detection and GC/MS. Brown and
    Weerasinghe (1976) further improved extraction of the oxidation
    products by substituting methanol for diethyl ether and modifying the
    chromatographic clean-up. The U.S. Food and Drug Administration
    multi-residue method for organophosphorus insecticides (FDA Pesticide
    Analytical Manual, Vol. I) will detect carbophenothion, the oxygen
    analogue, and the carbophenothion sulphone metabolites.


         Three countries responded to requests for information for the
    re-evaluation of carbophenothion by the 1976 Joint Meeting. There was
    no indication that the scope of carbophenothion uses has increased
    since the 1972 evaluation. No additional data from supervised residue
    trials were available. There was no new information on residue
    chemistry which would justify any changes in the previously
    recommended maximum residue limits. Some new information on the nature
    of carbophenothion residues and on analytical methods was evaluated.


         Because the further information required by the 1972 Joint
    Meeting has not been supplied, the temporary ADI and temporary maximum
    residue limits then recommended are withdrawn. In the absence of an
    ADI, the temporary limits are converted to guideline levels.


    REQUIRED (before an acceptable daily intake can be allocated and
    maximum residue limits can be recommended)

    1.   Studies to substantiate the marked species difference in
         sensitivity to plasma cholinesterase depression.

    2.   An adequate reproduction study.


    1.   Further elucidation of the nature of the terminal residues on
         crops, particularly as to possible presence under field
         conditions of photolysis products reported by Machin and


    FAO/WHO. 1972 Evaluations of some pesticide residues in 1973
                        foods. FAO/AGP/1972/M/9/1.

    Brown, P.M. & Torpey, C.L. Determination of carbopheniothion
    1976                residues in wheat plants grown from
                        carbophenothion-treated seeds. Pest Infestation
                        Control Laboratory, Ministry of Agriculture,
                        Fisheries and Food, unpublished.

    Brown, P.M. & Weerasinghe, D.K. Evaluation, development and
    1976                application of methods for extraction and analysis
                        of carbophenothion and its metabolites from avian
                        tissues. Unpublished report, Pest Infestation
                        Control Laboratory, U.K., Ministry of Agriculture,
                        Fisheries and Food.

    Jennings, D.M., Bunyan, P.J., Brown, P.M., Stanley, P.I., & Jones,
    1975                F.J.S. Organophosphorus poisoning; a comparative
                        study of the toxicity of carbophenothion to the
                        Canada Goose, the Pigeon and the Japanese Quail.
                        Pestic. Sci., 6:245-257.

    Machin, A.F., Quick, M.P., & Norman, I.M. Unpublished.

    Stanley, P.I., Brown, P.M., Martin, A.D., Steed, L.C., Westlake,
    1976                G.E., Howells, L.C. & Machin, A.F. The avian
                        toxicology of carbophenothion. Pest Infestation
                        Control Laboratory and the Central Veterinary
                        Laboratory, Ministry of Agriculture, Fisheries and
                        Food, unpublished.

    See Also:
       Toxicological Abbreviations
       Carbophenothion (ICSC)
       Carbophenothion (WHO Pesticide Residues Series 2)
       Carbophenothion (Pesticide residues in food: 1977 evaluations)
       Carbophenothion (Pesticide residues in food: 1979 evaluations)
       Carbophenothion (Pesticide residues in food: 1980 evaluations)
       Carbophenothion (Pesticide residues in food: 1983 evaluations)