WHO/FOOD ADD/71.42



    Issued jointly by FAO and WHO

    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
    Group on Pesticide Residues, which met in Rome, 9-16 November, 1970.



    Rome, 1971



    Chemical name

    2-chloroethyltrimethyl-ammonium ion (usually as the chloride)


    chlorcholine chloride, Cycocel(R), CCC


    [Cl CH2. CH2N (CH3)3]+Cl-

    Other information on identity and properties

    White crystalline solid, typical amine (fish like) odour. Soluble in
    lower alcohols; insoluble in ether and hydrocarbons; water solubility
    74 g/100 ml at 20°C.

    Aqueous solutions are chemically stable and retain their biological

    Purity of technical grade, 97 to 98 percent. Traces of 1,
    2-dichloroethane and trimethylamine occur as impurities.

    Commercial formulations include 10 percent, 40 percent and 50 percent
    solutions and 65 percent dust.


    Although considerable studies are reported to have been conducted on
    the biochemistry and toxicology of chlormequat, including short and
    long-term studies, much of this information was not available to the
    Meeting. In the absence of full reports on this subject, it was not
    possible to consider the toxicology of chlormequat. Therefore, no
    acceptable daily intake (ADI) was established at this time.


    Use pattern

    Chlormequat is registered in at least 17 countries as a plant growth
    regulator particularly to promote sturdier growth in wheat, rye and
    oats and thus reduce the risk of lodging. It is applied to wheat as a
    single treatment at the rate of 0.6-3.0 kg per hectare and to oats at
    the rate of 1-2 kg/ha when the cereal crop plants are 10-20 cm high
    (wheat) and 25 to 30 cm high (oats and rye). It is also used to
    improve the fruit set and yield of grapes (Coombe, 1965). For this
    purpose, 300 grammes of active ingredient is applied per hectare of
    vines one to three weeks before flowering.

    Chlormequat is used in a number of countries as a growth regulator for
    use on ornamentals to reduce vegetative growth and enhance flowering.
    Many other uses have been evaluated. While a number of these
    applications appear promising, there is as yet no acceptance of these
    uses on commercial food crops other than wheat, rye, oats and grapes.


    Residue data assembled from controlled experiments in Sweden, France,
    Netherlands, Germany, United Kingdom, Kenya and New Zealand show that
    when chlormequat is used to regulate the growth of wheat, rye and oats
    so as to give the plants added resistance to lodging, residues of the
    parent compound occur in the grain at harvest.

    Table I gives typical results obtained from supervised trials with
    wheat and rye.

        TABLE I

    Chlormequat residues in grain from crops treated to prevent lodging

                                       Chlormequat      Interval -
    Country           Type of Crop     kg/ha            treatment to      Residues
                                                        harvest-weeks     ppm

    Sweden            Rye A            2                13                1.0
    1967              Rye A            2                16                3.2
                      Rye B            2                14                4.2
                      Rye B            2                17                1.5

    1968              Rye C            2                14                0.57
                      Rye C            2                15                0.52
                      Rye C            2                17                0.36
                      Rye A            2                14                1.67
                      Rye A            2                15                1.2
                      Rye A            2                17                1.2

    United            Spring Wheat     1                12                0.75
    Kingdom           "      "         1                15                0.1
    1966              "      "         2                10                0.68
                      "      "         2                15                0.15

                      Winter Wheat     2.5              12                0.44
                      "      "         2.5              17                0.18

    United            Spring Wheat     1.0              22                0.4
    Kingdom           Winter Wheat     1.5              20                0.34

    TABLE I (cont'd)

    Chlormequat residues in grain from crops treated to prevent lodging

                                       Chlormequat      Interval -
    Country           Type of Crop     kg/ha            treatment to      Residues
                                                        harvest-weeks     ppm

    Sweden            Spring Wheat     2                12                0.23
    1965              Spring Wheat     2                15                0.1
                      Winter Wheat     3                12                1.5
                      Winter Wheat     3                18                0.13

    Netherlands       Wheat            2                12                0.65
    1965              Wheat            2                24                0.1

    Kenya             Wheat A          1                21                0.1
    1965              Wheat A          1.5              21                0.19
                      Wheat B          1.5              21                0.1

    France            Wheat            2.25             13                0.3
    1965              Wheat            4.5              13                0.4

    New Zealand       Wheat            2                17                0.4

    Jung (1964) examined 150 wheat samples from more than 20 field trials
    in West Germany during 1963 and established a distinct relationship
    between residues and the quantity of chlormequat applied. Using an
    analytical method sensitive to only 0.5 ppm, it was reported that no
    residues could be detected in the grain of crops sprayed early with 3
    kg/ha, and that only 23% of 22 samples from crops treated at the rate
    of 4.5 kg/ha contained detectable residues ranging around 0.5 ppm with
    a maximum of 1 ppm. Later trials (Jung, 1969a) on 12 crops and using
    more sensitive analytical procedures showed maximum residues of 0.47
    ppm when chlormequat was applied according to label recommendations.

    At rates of application of 1.0-1.5 kg per hectare and recommended
    harvest intervals, residues in the grain were most frequently in the
    range of 0.1-0.3 ppm, with an occasional value approaching 1 ppm
    (American Cyanamid Co., 1966b, 1968b; Cyanamid of Great Britain Ltd.,
    1965, 1966; Jung and Henjes, 1964).

    On the basis of these results, it appears that the residue level in
    wheat gradually declines, so that early treatment or slow maturing
    varieties are likely to have lower residues than those crops where
    treatment is applied closer to harvest. The range of residue values

    is, however, not great. Residues are not likely to exceed 1 ppm in
    wheat at harvest under normal conditions.

    Studies by Blinn (1967) using 14C-labelled chlormequat showed that
    0.2 ppm of the parent substance remained as a residue in the grain
    after the foliage had been treated 12 weeks previously.


    Jung (1968) evaluated the residues in short-straw winter rye treated
    as recommended in West Germany at 4 locations and found residues
    ranging from 1.0 to 1.3 ppm following the application of 1.8 kg/ha.

    Reports from other countries indicate that the residue levels in rye
    are somewhat higher than in wheat and often exceed 3 ppm. Numerous
    results appear in the range 3-4 ppm.


    Oats present a somewhat different problem in that the most effective
    results are obtained by treating when the crop has reached a height of
    40-50 cm. These late season treatments lead to residues in the grain
    of 3.8 ppm and 6.1 ppm from the use of 1.5 kg/ha and 3 kg/ha,
    respectively (Jung 1968a, 1969b).

    Residues in the whole grain have been reported (American Cyanamid Co.,
    1967, 1968a) to range from 0.16-4.2 ppm, depending upon rate of
    application, harvest interval and variety of plant.


    Experiments which were carried out in Australia (Annand, 1968) with
    the object of determining the residues resulting from the use of
    chlormequat sprays on grapes at flowering time had a sensitivity of
    0.75 ppm. No chlormequat residues could be found in grapes treated
    with sprays containing 300 ppm of chlormequat 16 weeks prior to
    harvest. Paper chromatography was used as an analytical method,
    because it was the most sensitive of the several methods available.

    Sultanas made by drying grapes grown with the aid of chlormequat
    treatment were also analysed by the same laboratory, but no residues
    were detected.

    Residues of 0.2-0.6 ppm have been found in the fruit at harvest, and
    similar levels in the finished wine products (American Cyanamid Co.,
    1969a, 1969b; Tafuri et al., 1970a).

    Fate of residues

    Blinn (1967) using 14C-labelled chlormequat showed the compound was
    not metabolized in wheat plants or in rats. The unchanged compound was
    the only radio labelled material found as residues in wheat foliage,
    roots and grain and in rat urine.

    It appears that chlormequat is absorbed by wheat foliage but undergoes
    no metabolism and very little translocation to the roots. Therefore,
    the residue analytical procedure developed by Mooney and Pasarela
    (1967) which responds to the parent chlormequat should provide
    realistic evaluation of the residual properties of chlormequat plant
    growth regulant in wheat foliage and grain.

    Blinn (1967) reported that over 96% of the compound was detected
    unchanged in the urine and faeces within 48 hours when rats were fed
    chlormequat in their diet. Less than 0.5% was respired as carbon
    dioxide in the breath, and less than 1 ppm was detected in tissues of
    sacrificed rats.

    Jung and El-Fouly (1969) applied high rates of chlormequat to wheat
    plants and showed that there is a slight increase in the choline
    chloride and betain content of the plant tissues 3 and 24 days after
    treatment. The authors proposed a theoretical basis for the metabolic

    In a study of factors affecting degradation of chlormequat by
    wheat-plant extracts (El-Fouly and Jung, 1969), it was suggested that
    an enzymatic system might be involved. Bier and Faust (1967), using
    chlormequat labelled with nitrogen-15 applied foliarly to intact wheat
    plants, showed that there is no metabolism of the compound to betaine,
    choline, dimethylchloroethylamine, or trimethylamine. A rate of
    disappearance study at a treatment level of 4 pounds of chlormequat
    per acre of wheat showed a biological half-life of 13 days (Mooney and
    Pasarela, 1967).

    Jung and El-Fouly (1969) showed that the residue in wheat grain
    (1.0-2.5 ppm) declined to 0.5 ppm and below after the wheat was held
    in store for 12 months. Residues are highest in grain grown under
    particularly dry conditions. High rainfall can, apparently, almost
    entirely eliminate the detectable residue in grain at harvest. The
    residue of chlormequat remaining in the straw of treated cereals is
    usually somewhat higher than the residue in the grain.

    Straw from treated crops will possibly be used as fodder for sheep and
    cattle. Jung (1969b) showed that when oat straw containing 5 ppm and
    10 ppm chlormequat was fed to a lactating cow, no residue could be
    found in milk. When fodder containing 20 and 40 ppm chlormequat (40
    and 80 mg/day) was fed, only traces of less than 0.1 ppm chlormequat
    could be traced in the milk. Examination of the urine of the test cow
    established that chlormequat was excreted quantitatively in the urine.

    Chlormequat residues in soil decompose relatively fast. Cathey and
    Stuart (1961) consider the persistency in soil to be only three weeks.
    Jung (1965) showed that soil applications were inactivated after 4
    weeks at 20°C.

    Evidence of residues in food in commerce or at consumption.

    No information was available on residues of chlormequat in food
    commodities moving in commerce nor have studies been conducted to
    determine residues in foodstuffs as consumed. Studies of the effect of
    processing and cooking on chlormequat residues appear not to have been
    carried out.


    A thin layer chromatographic method developed by Jung and Henjes
    (1964) was used in evaluating residues in field trials, but its
    sensitivity was limited to 0.5 ppm.

    Mooney and Pasarela (1967) have described a method for the
    chromatographic separation and subsequent colorimetric determination
    of chlormequat at residue levels in wheat grain and plants at various
    stages of growth. The compound, after extraction, is removed from the
    plant tissue background by adsorption on aluminum oxide and measured
    colorimetrically as a complex with dipicrylamine at 415 mµ.

    Based on both of these procedures, Jung and Henjes, (1969) developed a
    further method involving extraction with methanol, isolation by column
    chromatography using alumina and an acidic cation exchange resin and
    measurement as the dipicrylamine complex. The method is suitable for a
    wide variety of plant products, grain, wine and animal organs. The
    sensitivity ranges from 0.1 to 0.3 ppm with recoveries of 90-100%.
    This method is practically the same as used by Businelli et al. (1969)
    for the determination of chlormequat residues in tomatoes and grapes.
    Tafuri et al. (1970b) have reported a method for the gas
    chromatographic estimation of chlormequat at residue levels based upon
    a reaction with sodium benzenethiolate which converts chlormequat to
    1-phenylthio-2-dimethylaminoethane. Tafuri et al. (1970a) have used
    both the colorimetric and gas chromatographic methods for the
    determination of chlormequat residues in grapes and wine products.



    grapes and dried vine fruit - 0.75 ppm


    Chlormequat has been used during the past five years as a plant growth
    regulator to reduce the risk of lodging in wheat, rye and oats. It is
    applied to the growing wheat and rye when the first node can be felt
    in the majority of tillers and in oats when the second node can be
    felt. It is also used on grape vines to aid in the setting of the
    grape harvest and for increasing yields.

    Chlormequat is sold as an aqueous solution containing from 12% to 40%
    w/v active ingredient. In parts of Europe, a formulation containing
    46% chlormequat and 32% choline chloride is marketed. The addition of
    choline chloride reduced the acute toxicity of chlormequat to a range
    of laboratory animals but does not appear to modify the mode of action
    of chlormequat in plants.

    Technical chlormequat used in preparing commercial formulations is 97
    to 98% pure 2 chloroethyltrimethylammonium chloride.

    The data available to the meeting was obtained from published
    literature and from the major European and American manufacturers.
    Residue data were available from supervised trials carried out in a
    number of European countries, Kenya, New Zealand and Australia.

    Available data indicate that residues of unchanged chlormequat may
    occur in the straw and grain of treated small grain crops, especially
    wheat, rye and oats. Residues in wheat appear to lie mostly below 1
    ppm, but some samples, especially from crops grown under dry
    conditions, have residues ranging up to 22 ppm. Residues in rye appear
    somewhat higher, ranging up to 4 ppm. Residues in oats appear higher
    still, because treatment is applied when the crop is in a more
    advanced stage of development when the interval between application
    and harvest is much less. Residues in oats may range as high as 6 ppm.

    The feeding of straw from treated crops to dairy cows does not give
    rise to detectable residues in milk, nor is it to be anticipated that
    residues could occur in edible tissues of ruminants receiving such
    plant materials as forage.

    A specific method of analysis suitable for determining residues of
    chlormequat in cereal grain, plant products, fruit and vegetables and
    animal tissues at a sensitivity of about 0.2 ppm has been published.
    This method appears suitable from regulatory purposes as the
    extraction and cleanup procedure makes it highly specific.


    The following is an indication the maximum residues which will occur
    in specified food commodities following approved use of chlormequat.
    Residues will occur at this level only in some treated crops. The
    residue levels are not expected to decline significantly during
    storage of treated crops following harvest.

    Raw grains (rye and oats)         5 ppm

    Raw grain (wheat)                 2 ppm

    Grapes and dried vine fruits      1 ppm


    REQUIRED    (before an acceptable daily intake for man can be

    Full reports on the biochemical and toxicological studies conducted on


    1.   Information on other registered uses for chlormequat

    2.   Further information on residues in new agricultural commodities
         from a number of additional countries

    3.   Information on the effect of milling and preparation on the level
         of residues in grain products

    4.   Information on chlormequat residues in commodities moving in
         international trade

    5.   Analytical methods capable of recovering and determining
         chlormequat residues in plant and animal products at levels down
         to at least 0.1 ppm, to be established for regulatory purposes.


    Annand. (1969) Residues of chlormequat in grapes and dried vine
    fruits. Submission to National Health and Medical Research Council,

    Blinn, R.C. (1967) Plant Growth Regulant - Biochemical Behaviour of
    Chlormequat in Wheat and Rats. J. Agric. and Fd. Chem., 15 (6):

    Cathey, H.M. and Stuart, N.W. (1961) Comparative plant growth
    retarding activity of Amo 1618, Phosphon and CCC; Botan. Gaz., 123:

    Coombe, B.G. (1965) Increase in fruit set in Vitis vinifera by
    treatments with growth retardants, Nature, 205: 4968

    Jung, J. (1964) Analytical research on wheat samples of CCC-trials.
    Landw. Forschg., 17; 267

    Jung, J. and Henjes, G. (1964) Proof and half-quantitative
    determination of chlorcholinchloride (CCC) in wheat grain and straw.
    Zeitschr. f. Pflanzenernährg., Düngg. u. Bodenkde., 106: 108

    Jung, J. (1965) Behaviour of CCC in plants and soil. CCC-Symposium of
    the BASF, Limburgerhof

    Jung, J. (1968) CCC-residue in rye according to trial plan  DIII and
    DIIId. Internal BASF-Information

    Jung, J. (1968a) Residue trials with CCC-treated oat. Internal 
    BASF-Information No. 581, Limburgerhof

    Jung, J. and El-Fouly, M.M. (1969) On the decomposition of chlorine
    choline chloride (CCC) in the plant. Zeitschr. f. Pflanzenernährg.,
    Düngg. u. Bodenkde., 114: 128

    Jung, J. (1969a) Personal information to Herrn Professor Dr. Siegel,
    LUFA, Speyer

    Jung, J. (1969b) Results of the residue examination of CCC treated oat
    from the vegetation period 1968. Internal BASF-Information No. 617,

    Jung, J. and Henjes, G. (1969) Determination of the growth regulators
    CCC (chlorcholinchloride) and CMH
    (N-dimethyl-B-ethyl-chloride-hydrazone chloride) in biological material

    Mooney, R.P. and Pasarela, N.R. (1967) Determination of
    chlorcholinchloride residues in Wheat grain, straw and green wheat
    foliage. J. Agric. Fd. Chem., 15: 989


    An extensive bibliography containing over 280 references to papers on
    the properties, uses and mode of action of chlormequat has been
    published by American Cyanamid Company Wayne, New Jersey, U.S.A.,
    entitled "CYCOSTAT" Plant Growth Regulant

    See Also:
       Toxicological Abbreviations
       Chlormequat (WHO Pesticide Residues Series 2)
       Chlormequat (Pesticide residues in food: 1976 evaluations)
       Chlormequat (Pesticide residues in food: 1994 evaluations Part II Toxicology)
       Chlormequat (Pesticide residues in food: 1997 evaluations Part II Toxicological & Environmental)
       Chlormequat (JMPR Evaluations 1999 Part II Toxicological)