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    PARAQUAT         JMPR 1978

    Explanation

         At the 10th Session of the Codex Committee on Pesticide
    Residues, (Alinorm 79/24, para. 116), some delegations questioned
    the need to set the maximum residue limit for paraquat cation on
    sunflower seed as high as 2 mg/kg. As additional data were
    available the Committee requested the Joint Meeting to reconsider
    the limit at the earliest opportunity.

         Extensive data were obtained from supervised trials carried
    out in the USA in which paraquat was used as a desiccant and
    against late developing broad leaf and grass weeds.

    RESIDUES IN FOOD AND THEIR EVALUATION

    USE PATTERN

         Paraquat is sprayed during the three weeks prior to harvest at
    a dosage rate of 0.25-0.5 kg a.i./ha applied from the air or with
    ground equipment. This use hastens the drying rate of mature seed,
    reduces harvest losses and facilitates mechanical harvesting.

    RESIDUES RESULTING FROM SUPERVISED TRIALS

         The available data on residues in sunflower seed and its
    products are summarized in Table 1. Residues up to 0.9 mg/kg were
    found in the whole seed; no residues were found in the oil (limit
    of determination 0.01 - 0.05 mg/kg), as would be expected owing to
    the cationic nature of the compound. Residues up to 1.2 mg/kg were
    found in sunflower meal. Samples of oil were taken on all sampling
    dates; no residues were found.

         The residues in seeds, hulls, meal and oil were determined
    colorimetrically by a method based on that of Calderbank and Yuen,
    cited in FAO/WHO 1971b.

    APPRAISAL

         Paraquat is used as a desiccant and herbicide shortly before
    harvest (pre-harvest interval about 1 - 3 weeks). This use
    accelerates the drying of mature seeds, reduces the harvest losses
    and facilitates mechanical harvesting. Extensive residue data
    became available from supervised trials, carried out in three
    states of the USA. Residues up to 0.8 mg/kg were present in the
    whole mature seeds at harvest. It may be expected that further
    drying will increase the residue on a dry product basis to more
    than 1 mg/kg. Residues up to 1.2 mg/kg were found in sunflower
    meal, which is used as a component of compounded animal feed,
    whereas the residues in sunflower oil were very low, at or about
    the limit of determination of 0.01 mg/kg.


        TABLE 1. Residues of paraquat in sunflower seed and its products (supervised trials, USA)

                                                                                                                           

                                                           Residues (mg/kg) at intervals (days) after application
    Commodity      Country     Year      Application                                                                       
                                         rate, kg *
                                         a.i./ha           0              7              14             21             Ref.
                                                                                                                           

    Sunflower      USA         1972         0.5                           0.04-0.04      0.52-0.32      0.42-0.81      1
    seeds          Minn.

    seeds          USA         1972         0.25                          0.05-0.11      0.90-0.13      0.12-0.11
    meal           Minn.                                                  0.14-0.10      0.23-0.17      0.11-0.15      1
    hulls                                                                 0.08-0.07      0.10-0.07      0.07-0.09

    seeds          USA         1972         0.5                           0.27-0.21      0.37-0.39      0.32-0.60      2
                   Minn.

    seeds          USA         1972         0.25                          0.06-0.06      0.04-0.03      0.02-0.04
    meal           Minn.                                                  0.10-0.02      0.05-0.07      0.05-0.04      2
    hulls                                                                 0.06-0.06      0.04-0.06      0.02-0.02

    seeds          USA         1972         0.50                          0.51-0.35      0.44-0.40      0.23-0.26      3
                   Calif.

    seeds          USA         1972         0.25                          0.14-0.12      0.11-0.09      0.10-0.11
    meal           Calif.                                                 0.20-0.17      0.17-0.20      0.18-0.18      3
                                                                          0.14-0.16      0.14-0.11      0.08-0.11

    seeds          USA         1977         0.50           0.16-0.16      0.35-0.35      0.23-0.23
    meal           Calif.                                                 0.35-0.54                                    4
    hulls                                                                 0.57-0.67

    seeds          USA         1977         0.25           0.08-0.08      0.10-0.11      0.11-0.11
    meal           Calif.                                                 0.17-0.12
    hulls                                                                 0.23-0.27

    TABLE 1. (Cont'd.)

                                                                                                                           

                                                           Residues (mg/kg) at intervals (days) after application
    Commodity      Country     Year      Application                                                                       
                                         rate, kg *
                                         a.i./ha           0              7              14             21             Ref.
                                                                                                                           

    seeds          USA         1971         0.50           0.19-0.19      0.27-0.34      0.81-0.49
    meal           Miss.                                                  0.71-0.60
    hulls                                                                 2.18-4.63                                    5

    seeds          USA         1971                        0.04-0.07      0.31-0.10      0.38-0.52
    meal           Miss.                                                  0.64-1.16                                    5
    hulls                                                                 2.44-1.33
                                                                                                                           

         * All treatments were single applications of a liquid concentrate formulation

    

         Since sunflower meal can constitute up to 20% of the daily ration
    of dairy cattle, 15% of the diet of hens and up to 30% of the rations
    of other livestock animals, there is no chance that the residues
    occurring in sunflower oil used as basic material for manufacturing
    compounded animal feed will give rise to levels in products of animal
    origin exceeding the levels proposed by the 1976 Joint Meeting
    (FAO/WHO 1977 a,b).

    RECOMMENDATIONS

         In the light of the new and previously available data the maximum
    residue limit of 2 mg/kg for sunflower seed (dry) is reaffirmed. The
    following maximum residue limits are proposed in addition to those
    recommended at previous Meetings.

              Commodity                   MRL, mg/kg

              Sunflower meal
              (animal feed component)      2

              Sunflower oil
              (crude and refined)          0.05*

    * At or about the limit of determination.

    REFERENCES

    1 - 5 ICI/Chevron Paraquat: Desiccation of Sunflower (Helianthus
    (1978)              annua) Unpublished report provided by ICI, Plant
                        Protection Division, England to the 1978 JMPR.

    Calderbank, A. and S.H. Yuen An ion-exchange method for determining
    (1965)              paraquat residues in food crops. Analyst. 90:
                        99-106.
    


    See Also:
       Toxicological Abbreviations
       Paraquat (HSG 51, 1991)
       Paraquat (PIM 399)
       Paraquat (JMPR Evaluations 2003 Part II Toxicological)
       Paraquat (AGP:1970/M/12/1)
       Paraquat (WHO Pesticide Residues Series 2)
       Paraquat (Pesticide residues in food: 1976 evaluations)
       Paraquat (Pesticide residues in food: 1981 evaluations)
       Paraquat (Pesticide residues in food: 1982 evaluations)
       Paraquat (Pesticide residues in food: 1986 evaluations Part II Toxicology)