FAO Nutrition Meetings 
    Report Series No. 48A 
    WHO/FOOD ADD/70.39


    The content of this document is the 
    result of the deliberations of the Joint 
    FAO/WHO Expert Committee on Food Additives 
    which met in Geneva, 24 June  -2 July 19701

    Food and Agriculture Organization of the United Nations
    World Health Organization


    1 Fourteenth report of the Joint FAO/WHO Expert Committee on Food
    Additives, FAO Nutrition Meetings Report Series in press; Wld Hlth
    Org. techn. Rep. Ser., in press.


    Biological Data

    Biochemical aspects

    Dichloromethane (CH2CL2) is rapidly absorbed by the lungs (70-75% of
    the inhaled vapour). uniformly distributed in organs and rapidly
    excreted via the lungs and in the urine. It is largely excreted
    unchanged (von Oettingen et al., 1949; Riley et al., 1966). Because
    chlorinated hydrocarbon extraction solvents can react with -SH groups
    of protein aminoacids, the reaction of dichloromethane with L-cysteine
    was studied. The theoretical reaction product is djenkolic acid
    (1-1-di-(1,1-aminocarboxy -2 thioethyl)-methane) which has an acute
    oral LD50 of >1O g/kg body weight in mice. Under normal
    technological conditions practically none is found in the extracted
    material (Klimmer, 1970). Absorbed dichloromethane is probably
    hydrolysed in the liver to formaldehyde and HC1. Some of it also
    reacts with -SH groups of liver enzymes, e.g. coenzyme A (Heppel &
    Porterfield, 1948).

    Acute toxicity


    Animal        Route          LDS50            LD100       Reference

    Mouse         inhalation     56 mg/l air      -             Svirbely et al., 1947
                  inhalation     -                14 500 ppm    Flury & Zernik, 1931
                  i.p.           1.5 ml/kg        -             Klaassen & Plaa, 1966
                  s.c.           76 m moles/kg    -             Kutob & Plaa, 1962
    Rat           oral           2 g/kg           -             Klimmer, 1970
                  oral           1.6-2 g/kg       -             Dow Chemical Co., 1968
    Guinea-pig    inhalation     -                50 000 ppm    Nuckolls, 1933
    Rabbit        oral           -                1.9 g/kg      Spector, 1956
    Dog           oral           -                3g/kg         Barsoum & Saad, 1934
                  i.v.           -                200 mg/kg     Barsuom & Saad, 1934
                  i.p.           -                0.95 ml/kg    Klaassen & Paan, 1967
                  s.c.           -                2.7 g/kg      Barsoum & Saad, 1934
         This substance is a fairly strong but very volatile narcotic with
    an excitement stage, seen especially in rabbits and dogs, and
    incoordination in rats (Browning, 1965; Elkins, 1950). Mice were
    exposed to the LD50 vapour concentration for 24 hours and their SGPT
    elevation was determined to estimate hepatotoxic potential. This was
    found to be low (Gehring, 1968). Administration i.p. to mice of 1.5
    ml/kg produced albuminuria in 50% of animals with Decreased PSP
    excretion (Plaa & Larson, 1965).

         Mice injected s.c. with 20 m M/kg exhibited renal tubular
    necrosis, but BSP retention and liver histology were unaffected (Kutob
    & Plaa, 1962a).

         Administration i.p. of the LD50 to mice had no effect on SGPT
    retention or SGPT activity. The livers appeared histologically normal
    but the kidneys showed occasionally minimal necrosis of convoluted
    tubules (K1aassen & Plaa, 1966). Administration s.c. to mice of the
    LD50 caused some prolongation of pentobarbital sleeping time, but
    little change in BSP retention with normal liver histology (Kutob &
    Plaa, 1962).

         Oral administration to rats of 11.8 m M/kg by gavage had no
    effect on liver glutathione levels (Johnson, 1965). Inhalation of 5000
    ppm in air by  95 rats for 7 hours depressed the activity of rats as
    measured on activity drums although inspection showed no abnormality
    (Heppel & Neal, 1944). Higher levels reduce blood pressure and may
    injure the myocardium (von Oettingen, 1955). Administration i.p. to
    dogs of the LD50 produced elevation of SGPT in 50% of animals. No
    histological liver necrosis was seen but there was moderate neutrophil
    infiltration of the sinusoids. Renal histology was normal (Klaassen &
    Plaa, 1967).

    Short-term studies


         Groups of 30 male and 30 female Wistar II BR46 rats were given
    drinking water containing 0, or 125 ppm (i.e. about 2.8 mg/kg) for 91
    days, after which 10 male and 10 female rats/group were mated. The
    remainder were sacrificed. No effects were observed on body weight
    (both sexes), haematology, urinalysis, blood glucose, plasma free
    fatty acids (males) or oestrus cycle (females). No pathological
    changes were noted in sacrificed animals. Post-exposure reproduction
    was normal (Bornmann & Loeser, 1967).

         Four groups of 30 male and 30 female rats received either plain
    water. 4% alcohol, beer made with natural hops and beer made with a
    hop extract containing 2.2% dichloromethane for 13 weeks. However, no
    residues of dichloromethane were detectable in the beer. No difference
    was noted between test and control groups as regards haematology,
    urine analysis, major organ weights, blood chemistry and histology
    except for the expected fatty changes in the liver of the three test
    groups. The thyroids of the two test groups on beer had significantly
    smaller weights than the other two groups. No evidence of toxicity
    appeared in beer made with hop extract using dichloromethane (Bornmann
    et al., 1968).

         2 groups of 60 rats each received for 3 months as drinking fluid
    either water, coffee infusion containing 0.000012% or 0.012% of
    aqueous dichloromethane. No significant differences were seen between
    test and control animals as regards growth or other biological
    findings (Klimmer, 1970).

    Long-term studies

         No adequate information available.

    Special studies

         Rats, rabbits, dogs and guinea-pigs were exposed to
    dichloromethane up to 5000 ppm for varying periods up to 6 months. No
    serious adverse effects were seen except for occasional pulmonary
    oedema with focal necrosis and fatty degeneration of the liver. Higher
    doses produced liver damage in dogs and guinea-pig, but not in rats,
    rabbits or monkeys. Reproduction was unaffected (Heppel et al., 1944).

         Rabbit skin was treated with 0.5 g/kg for 5 days per week for 90
    days without any adverse effects (Dow Chemical Co., 1968),

    Observations in man

         Use as anaesthetic in man caused prenarcotic excitement but no
    other ill effects (Grasset & Gauthier, 1950). Excessive inhalation
    (2300 ppm) produces nausea. vomiting, also acute bronchitis and
    irritation of the conjunctiva and nose with some anaemia (Moskowitz &
    Shapiro, 1952). Most commonly drunkenness is produced (Patty, 1958).
    Skin absorption is small but it causes considerable irritation
    (Torkelson et al., 1966). The TLV is 500 ppm (Amer. Conf Gov. Ind.
    Hyg., 1969).

         4 human subjects had the skin of their thumb immersed in
    methylenechloride for 30 minutes. The mean peak alveolar concentration
    during exposure was 3 ppm. This fell to 0.7 ppm 2 hours after the
    exposure (Stewart & Dodd, 1964).


         The solvent is metabolically fairly stable and largely excreted
    unchanged. High dosage produces narcosis but a long history of
    industrial exposure indicates no major toxicity. There is no evidence
    that it produces toxic reaction products with -SH groups when used
    according to good manufacturing practice. The long-term data available
    were in an abridged form and there was therefore no way of judging the
    actual solvent intake in the test animals. However, in short-term
    studies food extracted with the solvent appeared to be non-toxic.

    Tentative Evaluation

         The use of this solvent should be restricted to that determined
    by good manufacturing practice, which is expected to result in minimal
    residues unlikely to have any significant toxicological effect.


    Amer, Conf. Gov. Ind. Hyg. (1969) Threshold Limit values for 1969

    Barsoum. G. S, & Saad, K. (1934) Quart, J. Pharm. Pharmacol., 7. 205

    Bornmann, G. & Loeser, A. (1967) Z. Lebnsmittel-Untersuch.-Forsch.,
    136, 14

    Bornmann, G., Herold, E., Loeser, A. & Opitz, K. (1968) Dtsch.
    Lebensm.-Runschau , 64, 167

    Browning, E. (1965) Toxicity and Metabolism of Industrial Solvents,
    Elsevier, Amstedam

    Dow Chemical Co. (1968) Unpublished Report submitted to WHO

    Elkins, H. B. (1950) Tile Chemistry of Industrial Toxicology, J. Wiley
    & Sons, New York and London

    Flury. F. & Zernik, F. (1931) Schadliche Gase. Springer, Berlin

    Food and Drug Authority (1967) Federal Register, USA, 121, 1039

    Gehring, P. J. (1968) Toxic. Appl. Pharmacol., 13, 287

    Grasset, J. & Gauthier, R. (1950) Sem. Hp., 26, 1280

    Heppel. L. A. & Neal, P. A. (1944) J. Ind. Hyg. Toxic., 26, 17

    Heppel, L. A. & Neal, P. A., Perrin, T. L., Orr, M. L. & Porterfield,
    V. T., (1944) J. Ind. Hyg., 26, 8

    Heppel, L. A. & Porterfield, V. T. (1948) J, Biol. Chem., 176, 763

    Johnson, M. K. (1965) Biochem. Pharmacol., 14 (9), 1383

    Klaassen. C. D. & Plaa, G. L. (1967) Toxic. appl. Pharmacol., 10,

    Klaassen, C. D. & Plaa, G. L. (1966) Toxic. appl. Pharmacol., 9, 139

    Klimmer, O.R. (1970) Report to Fremdstoffkommission DPG 5/7/68

    Kutob, S. D. & Plaa, G. L. (1962) Toxic. appl. Pharmacol., 4, 354

    Kutob, S.D. & Plaa, G. L. (1962a) J. appl. Physiol., 17, 123

    Moskowitz, S. & Shapiro, H. (1952) Arch. Ing. Hyg., 6 116

    Nuckolls, A. H. (1933) Underwriters' Laboratories Rept, Miscellaneous
    Hazards No. 2375

    Patty, F. A-(1958) Industrial Hygiene and Toxicology, II ed.,
    Interscience, New York

    Plaa, G. L. & Larson, R. E. (1965) Toxic. appl. Pharmacol., 7, 37

    Riley. E. C., Fassett, D. W. & Sutton, W. L. (1966) Amer. Ind. Hyg.
    Ass. J., 27, 341

    Spector, W. S. (1956) Handbook of toxicology, Vol. 1., Saunders,

    Stewart, R. D. & Dodd, H. C. (1964) Amer. Ind. Hyg. Assoc. J., 25

    Svirbely, J. L., Highman, B., Alford, W. C. & von Oettingen, W. F.
    (1947) J. Ind. Hyg. Tox., 29, 382

    Torkelson, T. R., Hoyle, H. R. & Rowe, V. K. (1966) Pest Control, July

    von Oettingen, W. F. (1955) Publ. Hlth Serv. Publ., 414

    von Oettingen. W. F., Powell, C. C., Sharpless, N. E., Alford, W. C. &
    Pecora, L. J. (1949) Natl. Inst. Health Bull., No. 191

    See Also:
       Toxicological Abbreviations
       Dichloromethane (ICSC)
       Dichloromethane (WHO Food Additives Series 30)
       Dichloromethane (IARC Summary & Evaluation, Volume 71, 1999)