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    FAO Meeting Report No. PL/1965/10/2
    WHO/Food Add/28.65

    EVALUATION OF THE HAZARDS TO CONSUMERS RESULTING FROM THE USE OF
    FUMIGANTS IN THE PROTECTION OF FOOD

    The content of this document is the result of the deliberations of the
    Joint Meeting of the FAO Committee on Pesticides in Agriculture and
    the WHO Expert Committee on Pesticide Residues, which met 15-22 March
    19651

    Food and Agriculture Organization of the United Nations
    World Health Organization
    1965

             
    1 Report of the second joint meeting of the FAO Committee on
    Pesticides in Agriculture and the WHO Expert Committee on Pesticide
    Residues, FAO Meeting Report No. PL/1965/10; WHO/Food Add./26.65.

    ETHYLENE DICHLORIDE

    Compound

         Ethylene dichloride

    Chemical name

         Ethylene chloride

    Synonyms

         1,2-dichloroethane; ethylene dichloride; glycoldichloride

    Emperical formula

         C2H4Cl2

    Structural formula

    CHEMICAL STRUCTURE 

    Relevant physical and chemical properties

    Physical state (atmospheric pressure, 20C): colourless liquid

    Boiling-point: 83.5C

    Odour: chloroform-like odour

    Lowest concentration in air which is detectable by odour: 50 ppm

    Flash point: ca 12C (open cup)

    Flammability limits in air: 6.2 to 15.9% by volume

    Solubility:

         Water: insoluble

         Organic solvents: soluble in most common organic solvents

    Specific gravity (liquid): 1.26

    Specific gravity (gas): 3.42

    Uses

         Ethylene dichloride, being flammable, is rarely used alone. When
    mixed with carbon tetrachloride it is extensively used as a liquid
    grain fumigant for bulk storage in bins or on floors. The mixture
    generally used is in the proportion of 3:1 by volume of ethylene
    dichloride and carbon tetrachloride, this being the smallest
    proportion of the latter which renders the mixture non-flammable. A
    small proportion of ethylene dibromide (e.g. 2.5 to 5% by volume) is
    occaaionaliy added to these or to other mixtures of ethylene
    dichloride and carbon tetrachloride to improve surface treatment.
    Rates of dosage of these mixtures for grain are usually between 1
    gallon for 5 tons and 1 gallon for 10 tons in a 7-day exposure period.

         The 3:1 mixture is also used for fumigating a variety of
    commodities in bags including grain, pulses and animal feeding stuffs
    usually on a fairly small scale in gas-tight chambers or other types
    of sealed containers but in some tropical countries large stacks of
    bagged grain have been treated under a covering of gasproof sheets.

    Residues

         During fumigation of cereal grains with ethylene dichloride or
    its mixtures with other halogenated hydrocarbons, relatively heavy and
    continuous sorption of the fumigant takes place (Winteringham, 1944).
    The amount sorbed is higher at lower temperatures. The adsorbed
    fumigant airs off slowly from whole grains over a period of months.
    During handling, cleaning or milling processes the amount of adsorbed
    fumigant is progressively reduced (Lynn and Vorkes, 1957). After
    milling, a greater proportion of ethylene dichloride is found in the
    bran than in the whole grain before milling (Conroy et al., 1957).

         When treated at 9 gallons/1000 bushels with 3:1 ethylene
    dichloride carbon tetrachloride mixture, triple the dose recommended
    by the United States Department of Agriculture, showed a maximum of
    140 ppm ethylene dichloride three days after application of fumigant
    (ibid). Loss of fumigant during tempering and cleaning processes was
    up to 70% and the maximum residue found in flour made from this batch
    was 5 ppm.

         When amounts of ethylene dichloride up to 10 times the residue
    found in the flour from the previous study were added to flour which
    was then made into loaves, no unchanged fumigant was found in the
    baked bread (Munsey et al., 1957). (Sensitivity of method 2 ppm.)

         When added to grain fed to cows, at levels up to 1000 ppm an 
    average of less than 0.25 ppm ethylene dichloride was found in the 
    milk. There appears to be no direct correlation between amounts of 
    ethylene dichloride added to the grain and that found in the milk 
    (Sykes and Klein, 1957).

         When a 140-lb bag of 85% extraction wheat flour was fumigated for
    48 hours in a 17.5 ft3 chamber at 25C with 300 g of ethylene
    dichloride applied as vapour (equivalent to 11.1 lb per ton of flour)
    the following amounts of residual ethylene dichloride in ppm were
    found after different periods of airing of the bag in still air (Pest
    Infestation Laboratory, 1943).

                                                       
                        1 hour     2 days      7 days
                                                       

    Surface of bag       1060       210          22

    Centre of bag        1030       350          46
                                                       

         Baking tests carried out after seven days of airing showed no
    detectable damage to baking quality and no taint of the fumigant was
    left in the finished bread.

    Effect of fumigant on treated crop

         There appears to be no reaction between ethylene dichloride and
    the constituents of grain. Ethylene dichloride added to grain can be
    recovered intact by steam distillation with a solvent extraction
    procedure (Heuser, 1964, personal communication).

    BIOLOGICAL DATA

    Biochemical aspects

         In rabbits ethylene dichloride is mainly exhaled unchanged and no
    metabolites have been described (Williams, 1959).

    Toxicological studies

    1. The fumigant

         Maximum permissible concentration in the atmosphere recommended
    for industrial hygiene in the United States is 50 ppm (200 mg/m3)
    (Anon, 1964). Other maximum allowable concentrations are 3.0 mg/m3
    (Ryazonov, 1959) and 4.0 mg/m3 (Borisova, 1960).

         In experimental animals corneal lesions have been produced by
    both subcutaneous and oral routes of administration (Hubbs and
    Prusmack, 1955).

    Acute toxicity

                                                                    
    Animal    Route         LD50 mg/kg          Reference
                            body-weight
                                                                    

    Mouse     oral            910            Smyth et al., 1936
    Rat        "              680            McCollister et al., 1956
    Rat        "              770            Smyth et al., 1936
    Rabbit     "              910            Smyth et al., 1936
                                                                    

         Animals fatally poisoned by ethylene dichloride (inhalation)
    showed hyperaemia and oedema of the lungs, degenerative kidney
    changes, damage to liver and adrenals (von Oettingen, 1955).

    Short- and long-term studies

         Groups of 4-6 female rats were exposed to single doses of varying
    concentrations of ethylene dichloride vapour for different lengths
    of time and an estimate of single doses having no observable adverse
    effects was made. For 12 000 ppm, 3000 ppm, 1000 ppm, 300 ppm and 200
    ppm the maximum time was 0.1, 0.3, 1.5, 3.0 and 7.0 hours
    respectively.

         Intermittent exposure of animals to various concentrations of
    ethylene dichloride vapour for 7 hours showed the following
    no-effect levels (full histopathological examination and clinical
    biochemical tests were reported): rat (15 male, 15 female) 151
    exposures in 212 days, 200 ppm; guinea-pigs (8 male) 121 exposures in
    170 days, 1000 ppm; guinea-pigs (8 female) 162 exposures in 226 days,
    1000 ppm; rabbits (2 male) 165 exposures in 232 days, 400 ppm and
    monkeys (2 male) 140 exposures in 212 days, 100 ppm (Spencer et al.,
    1951).

    2. The fumigated foodstuff

         Chickens fed for five days, pigs for 12 days and cattle for 7.5
    days with grain freshly treated with a fumigant containing 29.2% (by
    weight) of ethylene dichloride appeared unaffected. The level of
    ethylene dichloride in the grain was not stated and no
    histopathological examinations were made (Rowe et al., 1956).

    Comments on the experimental studies reported

    1. Quite high levels of ethylene dichloride may remain in whole grain
       after fumigation.

    2. These high residues fall markedly when the grain is processed and
       flour contains measurable but very low residues.

    3. There is no evidence that ethylene dichloride combines chemically
       with food constituents.

    Evaluation

         On the available toxicological evidence it is impossible to
    calculate an acceptable daily intake for ethylene dichloride. It
    should be used as a fumigant under conditions which will result in the
    lowest possible residues in the foodstuffs as consumed.

    Further work required

    1. Further investigation of the amount of the residual ethylene
       dichloride remaining in the food after treatment and the effect 
       on this of processing and cooking.

    2. Feeding studies should be carried out on two mammalian species to
       determine the effect of the long-term feeding of ethylene 
       dichloride with particular reference to reproduction.

    REFERENCES

    Anon. (1964) Threshold limit values for 1964, Arch. environm.
    Hlth, 9, 545

    Borisova, M. K. (1960) Predel' no Dopustimye Kontsentratsii
    Atmosfern. Zagryazneii, 4, 61

    Conroy, H. W., Walkden, H. H. & Farrell, E. (1957) J. Assoc. Off.
    Agric. Chem., 40, 163

    Hubbs, R. A. & Prusmack, J. J. (1955) J. Amer. med. Ass., 159, 673

    Lynn, G. E. & Vorkes, F. A. (1957) J. Assoc. Off. Agric. Chem.,
    40, 163

    McCollister, D. D., Hollingsworth, R. L., Oyen, F. & Rowe, V. K.
    (1956) Arch. industr. Hlth, 13, 1

    Munsey, V. E., Mills, P. A. & Klein, A. K. (1957) J. Assoc. Off.
    Agric. Chem., 40, 201

    von Oettingen, W. F. (1955) The halogenated aliphatic, olefinic,
    cyclic, aromatic and aliphatic-aromatic hydrocarbons, including the
    halogenated insecticides, their toxicity and potential dangers,
    Public Health Service Publ. No. 414

    Pest Infestation Laboratory (1943) Pest Infestation Research Report,
    87 (Unpublished document)

    Rowe, V. K., Hollingsworth, R. L. & McCollister, D. D. (1956) J.
    Agric. Food Chem., 2, 1318

    Ryazonov, V. A. (1959) Proc. Int. Clean Air Conf., Nat. Soc. for
    clean air, London

    Smyth, H. F., Smyth, H. F., jr & Carpenter, C. P. (1936) J. industr.
    Hyg., 18, 277

    Spencer, H. C. et al. (1951) Arch. industr. Hyg., 4, 482

    Sykes, J. F. & Klein, A. K. (1957) J. Assoc. Off. Agric. Chem.,
    40, 203

    Williams, R. T. (1959) Detoxication mechanisms, London, Chapman &
    Hall Ltd

    Winteringham, F. P. W. (1944) J. Soc. chem. Ind. (Lond.), 63, 144
    


    See Also:
       Toxicological Abbreviations
       Ethylene dichloride (FAO/PL:1967/M/11/1)