WHO/Food Add./24.65
    FAO Nutrition Meetings
    Report Series No. 38A


    The content of this document is the result of the deliberations of the
    Joint FAO/WHO Expert Committee on Food Additives which met 8-17
    December 1964a


    a Eighth Report of the Joint FAO/WHO Expert Committee on Food
    Additives, Wld Hlth Org. techn. Rep. Ser., 1965, 309; FAO
    Nutrition Meetings Report Series 1965, 38.


    CHEMICAL NAMES          Hexamethylenetetramine; methenamine; methamin;




    MOLECULAR WEIGHT        140.2

    DESCRIPTION             White odourless crystals, which sublime at
                            about 263°C.  1 g yields 1.2 of formaldehyde on
                            hydrolysis.  One part is soluble in 1.5 ml of
                            water or 12.5 ml of alcohol.

    USE                     As a preservative for fish, meat and pickles.

    Biological Data

    Biochemical aspects

    Formaldehyde and formic acid occur in fresh unpreserved cod-fish

    Formaldehyde and formic acid are excreted in the urine of dogs and
    cats fed a meal of fish not treated with preservatives, the source of
    these substances being trimethylamineoxide occurring naturally in fish
    muscle.3,4,5  The concentration of free formaldehyde in the urine of
    these dogs and cats given unpreserved fish was 4 to 5 times higher
    than that found in human subjects who had consumed fish preserved with
    hexamethylenetetramine.  Humans fed almost exclusively on unpreserved
    fish did not show an increase in the excretion of formaldehyde or
    formic acid.3

    Under acid conditions, or in the presence of proteins,
    hexamethylenetetramine decomposes gradually yielding ammonia and

    Hexamethylenetetramine liberates free formaldehyde in the stomach.7

    Intravenous infusion in dog of formaldehyde, 35 mg/kg as a 0.6%
    solution during 8 to 10 minutes, was carried out.  Two minutes after
    completion of the infusion them was no increase in formaldehyde but a
    high increase in the formic acid level in the blood.  The formic acid
    level decreased by 50% in 1 hour, by 75% after 2 hours, and was back
    to normal after 4 hours.  In vitro human blood oxidizes 30%
    formaldehyde (0.7 mg to 4 ml blood) to formic acid within 4 hours. 
    Addition of methylene blue (0.05% to 0.2%) results in a complete
    oxidation of the formaldehyde.8

    Experiments with 14C-labelled formaldehyde given by stomach tube to
    rats and mice showed that 5 minutes after application the
    radioactivity was distributed over the total body.  After 12 hours,
    approximately 40% had been expired as 14CO2, 10% had been excreted in
    the urine, and 1% in the faeces.  The homogenized whole animals
    contained 20% of the radioactivity after 24 hours and 10% after 96

    Further work on the metabolism of hexamethylenetetramine and
    formaldehyde is in progress.10,11,12

    Special studies

    Both hexamethylenetetramine13 and formaldehyde14 have been shown to
    act as mutagens in Drosophila.

    Acute toxicity


    Animal       Route               LD50                Reference
                              (mg/kg body-weight)

    Rat        intravenous           9200                  15

    Short-term studies

    Rat.  Two groups of 5 male and 5 female rats received respectively
    0.4 and 0.2 hexamethylenetetramine per day parenterally or by stomach
    tube for 90 days.  Groups of 15 male and 15 female rats were also
    given 0.4 g hexamethylenetetramine by stomach tube for 333 days. 
    During the latter experiment 9 males and 3 females died compared with
    1 male and 2 females in the control group.  In both experiments no
    macroscopic changes in organs were observed in the animals receiving
    hexamethylenetetramine, nor did the body-weight of the test animals
    vary from that of the controls.  However, a citrus yellow colour of
    the coat was noted.16

    Cat.  (Work In progress)  Since October 1963, 0.124%
    hexamethylenetetramine and 0.0375% formaldehyde have been fed in the
    diet to groups of 5 and 4 cats respectively.17

    Dog.  (Work in progress)  Since January 1963, 0.125%
    hexamethylenetetramine and 0.375% formaldehyde have each been fed to
    groups of 6 dogs.  In November 1963, 5 litters born after the
    commencement of the feeding trials were also included in the

    Long-term studies

    Mouse.  (Work in progress)  Since January 1963, 2 groups of 30 males
    and 30 females of a special strain of mice with a high incidence of
    spontaneous tumours (about 80% after 1 year) have been fed 1%
    hexamethylenetetramine and 0.15% formaldehyde respectively.17

    Rat.  (work in progress)  Since April 1963, rats have been fed 0.5%
    and 1% hexamethylenetetramine and 0.05% and 0.15% formaldehyde.17

    (Work in progress)  A long-term, seven-generation feeding study on
    rats was commenced in May 1963.  5 mg/kg and 50 mg/kg
    hexamethylenetetramine are given in the drinking-water.18

    (Work in progress)  In March 1964, a three-generation chronic toxicity
    test was begun, feeding rats 0.04%, 0.08% and 0.16%
    hexamethylenetetramine in the diet.19

    Repeated subcutaneous injections of 35-40% solutions of
    hexamethylenetetramine produced local sarcomas in 8 out of 14 rats.20

    (Work In progress)  Two groups of rats (15 male and 15 female) are
    being given twice weekly subcutaneous injections with 1 ml of a 40%
    solution of hexamethylenetetramine and 0.1% formaldehyde respectively.
    Two control groups, each having 7 male and 7 female rats, are being
    given respectively NaCl and saccharose solution of equal osmotic
    pressure to that of the 40% hexamethylenetetramine solution.


    The toxicological data are considered to be insufficient for
    evaluation of an acceptable level for use as a food additive in man.
    In addition, hexamethylenetetramine produces sarcomas in rats after
    subcutaneous injection and has a mutagenic action in insects.

    It is concluded that, pending the evaluation of the results of work
    now in progress, hexamethylenetetramine should not be used as a food
    additive in human foodstuffs.


    1.  Malorny, G. (1964) FAO Symposium on the Significance of
    Fundamental Research in the Utilisation of Fish, Paper No. WP/II/11

    2.  Amano, K. & Yamada, K. (1964) FAO Symposium on the Significanae of
    Fundamental Research in the Utilisation of Fish, Paper No. WP/II/9

    3.  Malorny, G. & Rietbrock. N. (1962) Naturwissenschaften 49, 520

    4.  Malorny, G., Rietbrock, N. & Schassan, H. H. (1963) Arch. exp.
    Path. Pharmak., 246, 62

    5.  Schassan, H. H. (1963) Inauguraldissertation, Hamburg

    6.  Hutschenreuter, H. (1956) Z. Lebensmitt.-Untersuch., 104, 161

    7.  Malorny. G. & Rietbrock. N. (1963) Vortrag auf der X. Tagung des
    Ernährungswissenschaftlichen Beirats der deutschen Fischwirtschaft,

    8.  Malorny. G., Rietbrock. N. & Schneider, M. (1964) Arch. exp. Path.
    Pharmak., 247, 381

    9.  Buss, J., Kuschinsky, K., Kewitz, H. & Koransky, W. (1964) Arch.
    exp. Path. Pharmak., 247, 380

    10.  Malorny, G., Rietbrock, N. & Schneider, M. (1964) Der
    Stoffwechsel des Formaldehyds. 1. Die Oxydation des Formaldehyds im
    Blut (In preparation)

    11.  Malorny, G. & Reitbrock, N. (1964) Pharmakologisch-toxikologische
    Wirkungen des Hexamethlentetramins und seines Spaltproduktes
    Formaldehyd (In preparation)

    12.  Malorny, G., Netter, K. J. & Seidel, G. (1964) Untersuchungen
    über die Hemmbarkeit enzymatischer Reaktionen durch Formaldehyd und
    einige seiner Homologen (In Preparation)

    13.  Auerbach. C. (1951) Cold Spr. Harb. Symp. quant. Biol., 16, 199

    14.  Rapoport. I. A. (1946) C.R. Acad. Sci. USSR, 54, 65

    15.  Langecker. H. (1954) Arch. exp. Path. Pharmak., 221, 166

    16.  Brendel. R. (1964) Arzneimittel-Forsch., 14, 51

    17.  Kewitz, H. (1964) Work in progress, Institute for Veterinary
    Pharmacology, Free University of Berlin

    18.  Malorny, G. (1964) Work in progresss, Pharmacological Institute,
    University of Hamburg

    19.  Berglund, F. (1964) Work in progress, National Institute of
    Public Health, Stockholm

    20.  Watangabe, G. & Sugimoto, S. (1955) Gann, 46, 365

    See Also:
       Toxicological Abbreviations
       Hexamethylenetetramine (ICSC)
       Hexamethylenetetramine (WHO Food Additives Series 1)
       Hexamethylenetetramine (WHO Food Additives Series 5)