Sponsored jointly by FAO and WHO


    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
    Rome, 24 September - 3 October 1984

    Food and Agriculture Organization of the United Nations
    Rome 1985



         Fenitrothion was evaluated by the Joint Meeting in 1969, 1974,
    1976, 1979, 1982 and 1983.1/  Information was required by the 1983
    meeting on current good agricultural practices and on the results of
    supervised trials carried out on varieties of citrus fruit according
    to use recommendations.



         The meeting received only minor information on recommended uses,
    national maximum residue limits, monitoring data and on the fate of
    residues in stored wheat and in chicken tissue. Information on
    registered uses has been received from Canada, the Netherlands and New
    Zealand. Codex maximum residue limits exist for all uses.


         In addition to trials made in Spain on fenitrothion on mandarins,
    which were reported in 1983, trials have been made on fenitrothion on
    oranges. Sumithion 50 percent EC and Folithion 50 percent EC were
    applied in Valencia on oranges at a rate of 4.5 kg a.i./ha in a
    concentration of 0.15 percent. The average residue in whole fruit was
    1.18 mg/kg and 0.93 mg/kg 14 days and 28 days after treatment. Residue
    levels in pulp 14 days and 28 days after both treatments were
    0.03 mg/kg or lower.


    In Plants

         Although the fate of residues of fenitrothion in stored cereals
    has been reviewed previously (1974, 1976, 1977 and 1979), additional
    information was provided to this meeting. Earlier investigations were
    mainly on the degradation rate of the parent compound and to some
    minor extent on metabolism of fenitrothion to the oxygen analogue and
    3-methyl-4-nitrophenol. An investigation has now been made on the
    degradation to other metabolites of fenitrothion in stored wheat. Hard
    red spring wheat with a moisture content of 12.5 percent was treated
    with fenitrothion to provide a deposit of 12 mg/kg. After mixing, the
    wheat was transferred to screw-capped jars and stored in the dark at


    1/   See Annex 2 for FAO and WHO documentation.

    20C for 12 months. Samples were taken after 0, 1, 3, 6 and 12
    months for quantitative determination of fenitrothion and the
    following metabolites: fenitro-oxon, O-dimethyl-fenitrothion,
    S-methyl-fenitrothion, 3-methyl-4-nitrophenol,
    dimethyl-phosphorothioate and O-dimethyl-S-methyl-fenitrothion.

         The samples were extracted with acidified acetone or methanol
    and, after concentration, separations were made by partitioning to
    organic solvents from acidified or basic aqueous solutions. The
    metabolites present were ethylated by diazoethane and clean-up was
    made by column chromatography. Determinations were made by GLC using a
    flamephotometric detector (phosphorus mode) and an EC-detector. The
    presence of the metabolites was confirmed by TLC and for
    dimethyl-fenitrothion also by chemical derivatization. After 12
    months' storage, fenitrothion residue was decreased to 2 mg/kg.
    O-dimethyl-fenitrothion, 3-methyl-4-nitrophenol and dimethyl
    phosphorothioate were the major metabolites. The highest levels of
    O-dimethyl-fenitrothion and dimethyl-phosphorothioate were found after
    six months of storage; the residues, 2.01 mg/kg and 0.55 mg/kg,
    respectively, decreased after 12 months to 0.98 mg/kg and 0.21 mg/kg.
    Residues of 3-methyl-4-nitrophenol increased during the storage period
    from 0.38 mg/kg after one month to 0.96 mg/kg after 12 months. No
    fenitrothion or S-methyl-fenitrothion was detected throughout the
    study period. Detection limits were 0.001 mg/kg and 0.05 mg/kg,
    respectively (Abdel-Kader & Webster, 1982).

    In Animals

         The fate of residues of fenitrothion in mammals was reviewed in
    1969 and 1974. A study has been made on residues of fenitrothion and
    its metabolites in chicken tissue after long-term exposure to small
    doses. The results from this study show that chicken tissues retain
    insignificant amounts of fenitrothion or its metabolites even after a
    long exposure to small doses of this insecticide. This is consistent
    with earlier observations made on tissues for mammals (Trottier &
    Jankowska, 1980).


         Monitoring data from 1981-83 have been received from Sweden
    (1984a) on fenitrothion in domestic and imported crops of carrot,
    dill, lettuce, lemon, mandarin and orange. A total of 483 samples of
    domestically grown crops and 1 720 samples of imported crops were
    analysed. In 98.5 percent of the samples residues were <0.11 mg/kg.
    One sample of dill had a residue higher than 0.5 mg/kg and 14 samples
    from 1 032 samples of mandarins and oranges contained residues between
    0.29 and 0.8 mg/kg.


         Updated lists of MRLs were provided to the meeting by the
    Netherlands (1984) and Sweden (1984b)


    Country               Commodity                MRL (mg/kg)

    The Netherlands       Fruit                    0.5
                          Vegetables               0.5
                          Cereals                  0.5
                          Tea                      0.5
                          Cocoa bean               0.1
                          Milk                     0.002 (limit of
                          Meat                     0.05 (limit of
                          Other food               0 (0.02) (limit of

    Sweden                Fruits and Vegetables    0.5
                          Potato                   0.2
                          Cereals and bran         0.5
                          Flour from cereals       0.2


         Limited information was received on recommended uses, results of
    supervised trials, monitoring data, national maximum residue limits
    and the fate of fenitrothion in chickens and in stored wheat.

         The meeting received data from a supervised trial with oranges,
    which supplemented information received by the 1983 JMPR on trials
    with mandarins. Residues in the whole fruit were 1.2 mg/kg after 14
    days and 0.93 mg/kg after 28 days. This supports the TMRL for oranges
    of 2 mg/kg proposed as an amendment to the Codex MRL. Residues in the
    pulp were 0.03 mg/kg or lower.

         Studies of the metabolism of fenitrothion in wheat stored at 20
    in the dark showed that levels of O-dimethyl-fenitrothion and
    dimethyl-phosphorothioate increased for six months after treatment and
    then decreased, but with a considerable residue remaining even after
    12 months. Levels of 3-methyl-4-nitrophenol increased during the
    whole 12-month period after treatment. No fenitro-oxon or
    S-methyl-fenitrothion was observed.

         The metabolism of fenitrothion has been investigated in the
    chicken after long-term exposure to small doses. No significant
    amounts of fenitrothion or metabolites were retained in the tissue.
    This is consistent with earlier observations made on mammalian


    Abdel-Kader, M.H.K. & Webster, G.R.B. Analysis of fenitrothion and
    1982      metabolites in stored wheat. Intern. J. Environ. Anal.
              Chem., 11: 153-165.

    Netherlands. National maximum residue levels of fenitrothion.

    Sweden. Monitoring data from the National Food Administration,
    1984a     Uppsala.

    Sweden. National maximum residue levels of fenitrothion.

    Trottier, B.L. & Jankowska, I. In vivo study on the storage of
    1980      fenitrothion in chicken tissues after long-term exposure to
              small doses. Bull. Environment. Contam. Toxicol., 24:

    See Also:
       Toxicological Abbreviations
       Fenitrothion (EHC 133, 1992)
       Fenitrothion (HSG 65, 1991)
       Fenitrothion (ICSC)
       Fenitrothion (FAO/PL:1969/M/17/1)
       Fenitrothion (WHO Pesticide Residues Series 4)
       Fenitrothion (Pesticide residues in food: 1976 evaluations)
       Fenitrothion (Pesticide residues in food: 1977 evaluations)
       Fenitrothion (Pesticide residues in food: 1979 evaluations)
       Fenitrothion (Pesticide residues in food: 1982 evaluations)
       Fenitrothion (Pesticide residues in food: 1983 evaluations)
       Fenitrothion (Pesticide residues in food: 1986 evaluations Part II Toxicology)
       Fenitrothion (Pesticide residues in food: 1988 evaluations Part II Toxicology)
       Fenitrothion (JMPR Evaluations 2000 Part II Toxicological)