IPCS INCHEM Home


    FAO/PL:1967/M/11/1
    WHO/Food Add./68.30

    1967 EVALUATIONS OF SOME PESTICIDE RESIDUES IN FOOD

    THE MONOGRAPHS

    The content of this document is the result of the deliberations of the
    Joint Meeting of the FAO Working Party of Experts and the WHO Expert
    Committee on Pesticide Residues, which met in Rome, 4 - 11 December,
    1967. (FAO/WHO, 1968)

    FOOD AND AGRICULTURE ORGANIZATION OF THE UNITED NATIONS
    WORLD HEALTH ORGANIZATION
    Rome, 1968

    ETHYLENE DIBROMIDE

    This pesticide was evaluated by the 1966 Joint Meeting of the FAO
    Working Party and the WHO Expert Committee on Pesticide Residues
    (FAO/WHO, 1967). Since the previous publication the results of
    additional experimental work have been reported. This new work is
    summarized and discussed in the following monograph addendum.

    EVALUATION FOR TOLERANCES

    USE PATTERN

    Other uses

    In addition to the previously described uses, ethylene dibromide may
    be used as a soil fumigant for nematode control.

    RESIDUES RESULTING FROM SUPERVISED TRIALS

    Beckman et al. (1967) have reviewed the inorganic content of
    foodstuffs due to soil treatment with fumigants. Since organically
    bound bromine is not taken up by plants from the soil, they authors
    interpret any bromine increase in the plants as being due to the
    bromide fumigant used. In general, the leafy portions of plants
    contain the most bromide but the edible portions of certain other
    crops also take up significant amounts of bromides as the result of
    soil fumigation. Results for ethylene dibromide (and for
    1,2-dibromo-3-chloropropane) are given in Tables I and II, which
    relate to the range of total inorganic bromide residues found in crops
    grown on triplicate (mainly) plots treated at Davis, California in
    1964 and 1965. Most crops were harvested about 100 days after soil
    treatment; but intervals ranged from 55 days (strawberries) to 10
    years (walnuts). Residues occurred notably in beet tops, string beans
    and spinach.

        TABLE I
                                                                                     

    Total Inorganic Bromide in Crops Grown on Treated Soils, 1964

                      Recovery     Time (days              Bromide (ppm)
                      fortified     treatment      Check
                        crop       to harvest)    sample       DBCP           EDB
                                                                                     

    Cottonseed           70.5          185         0.6          NT         0.4- 2.8

    Cottonseed           70.5          206         0.8       1.0- 2.2         NT

    Cottonseed           92            150         3.2       5.2- 7.6         NT

    TABLE I (cont'd)
                                                                                     

    Total Inorganic Bromide in Crops Grown on Treated Soils, 1964

                      Recovery     Time (days              Bromide (ppm)
                      fortified     treatment      Check
                        crop       to harvest)    sample       DBCP           EDB
                                                                                     

    Green beans          88             73         2.4       3.4-13.0      4.0-24.0

    Green beans          76             87         0.4       1.1- 1.6      8.0- 2.5

    Green beans          70            103         0.1       0.5- 2.8      0.5- 2.4

    Baby lima beans      74.4          103         0.1       4.0- 8.2      1.0- 8.5

    Beans, black eye     70             96         0.3       6.0- 9.9      3.9- 6.3

    Okra                 48.5                      0.5       0.4- 2.9      3.5-13.0

    Turnip               70             72         2.4       3.4-13.0      4.0-24.0

    Turnip greens         7             51         1.4      22.0-47.0     28.0-63.0

    Spinach              82             72         4.6      25.0-52.0     20.0-73.0

    Radish              110             49         2.0      12.0-26.0     15.0-33.0

    Table beet tops      70             72         6.0      54.0-94.0     52.0-72.0

    Cherries             70            180         0.6            0.7         NT
                                                                                     

    TABLE II
                                                                                        

    Total Inorganic, Bromide in Crops Grown on Treated Soils, 1965

                      Fortified      Time (days             Bromide residue (ppm)
    Crop                std.          treatment       Check
                    (% recovery)    to harvest)      sample         DBCP          EDB
                                                                                        

    Beans                 100           78             0.3       3.1- 7.4      11.0-22.0

    Beans                 100           88             0.3       5.5-14.0       8.0-14.0

    Beans                  95           98              *        1.8- 4.6       7.4-15.0

    Beans, dry black eye   95          147             0.3       2.4- 5.5       3.2- 4.0

    TABLE II (cont'd)
                                                                                        

    Total Inorganic, Bromide in Crops Grown on Treated Soils, 1965

                      Fortified      Time (days             Bromide residue (ppm)
    Crop                std.          treatment       Check
                    (% recovery)    to harvest)      sample         DBCP          EDB
                                                                                        

    Baby lima beans        90          155              *        0.3- 1.1       0.6- 1.4

    Sweet corn             70           95             0.4       2.0- 3.9       1.1- 4.4

    Okra                   92        78-89             2.0       8.0-20.0       3.7- 8.6

    Hop-flower             94           91              *            16.0         NT

    Prunes                 80          173             0.3       0.7- 0.9         NT

    Tokay grape            94            3 yr.         0.9       0.8- 1.4         NT

    T.S. grape             92          270             1.2       0.3- 2.3         NT

    T.S. grape             92            1 yr.         0.9            1.1         NT

    T.S. grape             98            4.5 yr.       1.2       0.3- 0.7         NT

    Sugar beet tops        89          147            17.8      43.0-78.0     66.0-224.0

    Sugar beet tops        80          322             9.5      18.0-38.0     27.0- 92.0

    Sugar beet roots       80          322             3.9       7.0-21.0     33.0- 83.0

    Walnuts                80          510              *        1.8-10.0         NT

    Walnuts                80           10 yr.          *        0.2- 1.2         NT

    Cottonseed             85          183              *        1.6- 6.4         NT
                                                                                        

    * less than 0.2           NT = no treatment
    
    FATE OF RESIDUES

    In storage and processing

    The nature of terminal residues arising from the use of ethylene
    dibromide and other fumigants was reviewed by the IUPAC Commission on
    Terminal Residues in 1967. The Commission stressed the need for a
    method of analysis sensitive to 0.1 ppm of unchanged ethylene
    dibromide in order further to evaluate the levels of this in food as

    consumed, especially insofar as this might indicate that no residues
    other than (a) inorganic bromide and (b) unchanged ethylene dibromide
    might be present as the result of ethylene dibromide treatment.

    The following note is adapted from a memorandum on terminal residues
    arising from the use of fumigants, prepared for IUPAC meetings in
    August (IUPAC, 1967a).

    "The pertinent question which needs to be resolved is whether ethylene
    dibromide leaves the grain completely upon a certain period of
    aeration (this may be highly variable and not dependable without
    analysis) or whether normal food processing and cooking will
    completely aerate ethylene dibromide or hydrolyze it. The nature and
    the amount of bromide residue occurring as a result of fumigation with
    liquid grain fumigants containing ethylene dibromide was determined by
    the use of radioactive bromide-82 (Anon. 1963). Ethylene dibromide was
    completely absorbed by wheat grain. About 50 per cent, presumably
    ethylene dibromide, was given off by heat treatment at 110-120C for
    one hour. The remaining bromide non-volatile compounds are only
    slightly extractable with organic solvents by Soxhlet extraction for
    ten hours and are water soluble, probably a mixture of sodium and
    potassium bromide. After five days contact with the grain, 50 per cent
    of the original ethylene dibromide was changed to inorganic bromide.
    The remaining 50 per cent can be volatilized in 59 hours in open air.
    Contrary to the use of uncooked grain for domestic animals and birds,
    man eats very little grain that is not processed in some way. Ethylene
    dibromide is lost from treated grain via turning, aeration, tempering,
    milling, etc. to a small percentage of the original level before
    cooking. Stenger and Mapes (1957) showed that when wheat flour
    containing 8 ppm ethylene dibromide was baked into broad rolls, the
    ethylene dibromide itself did not survive the baking process. The
    sensitivity of the analytical method used was 1 ppm of ethylene
    dibromide. Munsey, et al (1957) in a baking study, added 15 and 20 ppm
    of ethylene dibromide (10  the levels resulting from usual
    fumigations) to the flour and bread bases, prior to baking one-pound
    loaves of bread. The analyses of the baked bread showed that there was
    no ethylene dibromide per se remaining after baking within the
    analytical limits of the method (1 ppm). Rolled oats treated to attain
    about 10 times the expected residue level of ethylene dibromide, quick
    cooked for one minute, reduced ethylene dibromide 51 per cent from
    24.4 to 12 ppm. Considering normal processing procedure for producing
    rolled oats, it seems very unlikely that any measurable amount would
    be left in cooked commercial rolled oats."

    METHODS OF RESIDUE ANALYSIS

    In reviewing methods of analysis for unchanged residues arising from
    the use of ethylene dibromide, the IUPAC Commission on Residue
    Analysis (IUPAC, 1967b) also drew attention to the possibility that
    small residues of modified (and possibly more toxic) compounds might
    not be detected by such methods. The Commission recognised the
    desirability of studies on the recovery of ethylene dibromide from
    treated produce, however (using chromatographic techniques for the

    unchanged fumigant and by established methods for the increase in
    inorganic bromide arising from the fumigation). In its review the
    Commission made special reference to the progress of work on
    multidetection systems for unchanged residues from mixed fumigants,
    including mixtures containing ethylene dibromide. Heuser and Scudamore
    (1967b) have shown that cold extraction with 5:1 v/v acetone-water is
    far more effective than the various steam distillation methods
    described earlier for the recovery of residues of unchanged ethylene
    dibromide and other fumigants from flour. Residues have been extracted
    by this method from flour and from ground whole wheat by shaking with
    the solvent in a stoppered vessel. Aliquots of the clear supernatant
    liquor were injected into a gas chromatograph using a 50 per cent w/w
    polypropylene glycol on a chromosorb W column and flame-ionization
    detector. A specially designed injection unit was developed for this
    purpose. Recoveries or these substances were from 95 - 100 per cent,
    checked by independent vapour-phase application and subsequent
    aeration techniques, with chemical analysis of the vapours removed.
    Carbon disulphide is expected to yield a similar result and it is
    highly probable that residual amounts of other fumigants such as
    carbon tetrachloride, ethylene dichloride and acrylonitrile are
    extracted with equal efficiency by this solvent. However, the
    proximity of their boiling points to that of acetone makes the gas
    chromatographic separation of minute amounts from the solvent peak
    difficult. Present investigations are concerned with the use of the
    electron-capture detector for these and other compounds since it is
    relatively much less sensitive to acetone; and with the search for a
    suitably effective higher-boiling solvent which would widen the
    application of the flame ionization detector. Wit and Grevenstuk
    (1967) at Utrecht are working on the determination of unchanged
    ethylene dibromide and other fumigant residues in wheat, using the
    distillation-extraction method followed by gas-liquid chromatographic
    analysis with electron capture detection. Bielorai and Alumot (1966)
    have continued residue determinations on whole cereals using a similar
    technique but the proprietary fumigant mixtures used in this work did
    not include ethylene dibromide.

    NATIONAL TOLERANCES

    While there are no tolerances for residues of unchanged ethylene
    dibromide, tolerances for inorganic bromide resulting from the use of
    ethylene dibromide for fumigation (in conjunction with methyl bromide)
    have been published in the U.S. Federal Register (1966) as follows :

              Dried egg, processed herbs, apiece           400 ppm

              Barley, corn, milo (sorghum) rice,
              rye, wheat flours                            125 ppm

    RECOMMENDATIONS FOR TOLERANCES

    No change from previous recommendation (FAO/WHO, 1967).

    Previous considerations have been on the basis of an acceptable daily
    intake of 1 mg/kg of inorganic bromide (FAO/WHO, 1967). Tolerances
    proposed at the previous meeting (FAO/WHO, 1967) have since bean
    considered at the Second Session of the Codex Committee on Pesticide
    Residues (September 1967).

    The general position may be summarized as follows :

    Although the residual ethylene dibromide content of flour and various
    milling fractions have been measured in experimental procedures on
    numerous occasions, almost all of this work is based on the
    measurement of inorganic bromide residues; or the difference between
    such residues before and after airing. The general significance of
    results obtained in this way was summarized in a previously published
    document (FAO/WHO, 1965): ethylene dibromide has poor powers of
    penetration, is strongly absorbed by cereals but appears to be mainly
    unchanged (i.e. only a small proportion is converted to ionized
    bromide), is resistant to dispersion by airing but is largely lost by
    volatilization on baking or cooking.

    Limited results for commercial shipments of wheat were subsequently
    reported (FAO/WHO, 1967): only one shipment in 227 contained unchanged
    ethylene dibromide (0.5 ppm).  Unchanged ethylene dibromide could not
    be detected in 99 cargoes of wheat shipped from all parts of the
    world, using a method sensitive to 2 ppm. There appears to be no
    corresponding information at all for dry goods such as spices and
    dried fruit.

    FURTHER WORK

    Further work desirable

    In addition to that listed in the previous publication (FAO/WHO, 1967)
    the application of recently developed methods of extraction (Heuser
    and Scudamore, 1967a) and chromatographic analysis to cereals and
    flour in commerce is most desirable.

    REFERENCES PERTINENT TO EVALUATION FOR TOLERANCES

    Anon. (1963) Residues resulting from the fumigation with liquid grain
    fumigants containing ethylene dibromide. The Dow Chemical Company,
    Midland, Michigan.

    Beckman, H., Crosby, G.C., Allen, P.T. and Mourer, C. (1967) The
    inorganic bromide content of foodstuffs due to soil treatment with
    fumigants. J. Food Sci 32: 138-140

    Bielorai, R. and Alumot, E. (1966) Determination of residues of a
    fumigant mixture in cereal grain by electron capture gas
    chromatography. J. Agr. Food Chem. 14: 622.

    Bondi, A. and Alumot, E. (1966) Final Report of Research Conducted
    under Grant Authorized by Public Law 480. Effect of Ethylene Dibromide
    Fumigated Feed on Animals. USDA, Washington, D.C.

    FAO/WHO. (1965) Evaluation of the toxicity of pesticide residues in
    food. FAO Meeting Rept. PL/1965/10/1; WHO/Food Add./27.65.

    FAO/WHO. (1967) Evaluation of some pesticide residues in food. FAO
    PL:CP/15; WHO Food/Add./67.32

    Heuser, S.G. and Scudamore, K.A. (1967a) Analyst 92: in press

    Heuser, S.G. and Scudamore, K.A. (1967b) Determination of ethylene
    chlorohydrin, ethylene dibromide and other volatile fumigant residues
    in flour and whole wheat. Chem. Ind. 1557-1560.

    IUPAC. (1967a) Commission on Terminal Residues: Proceedings of the
    Meeting held in Vienna, Appendix VIII.

    IUPAC. (1967b) Commission on Residue Analysis: Proceedings of the
    Meeting held in Vienna, Appendix XV.

    Munsey, V.E., Mills, P.A. and Klein, A.K. (1957) J. Assoc. Off. Agr.
    Chem. 40: 201

    Stenger, V.A. and Mapes, D.A. (1957) J. Assoc. Off. Agr. Chem. 40:
    196.

    U.S. Federal Register. (1966) 1 October.

    Wit, S.L. and Grevenstuk, W. (1967) Private communication quoted in
    Appendix XV to Proceedings of IUPAC Commissions 1967.
    


    See Also:
       Toxicological Abbreviations
       Ethylene dibromide (ICSC)
       Ethylene dibromide (FAO Meeting Report PL/1965/10/2)
       Ethylene dibromide (FAO/PL:CP/15)
       Ethylene dibromide (FAO/PL:1968/M/9/1)
       Ethylene Dibromide (IARC Summary & Evaluation, Volume 71, 1999)