TECNAZENE        JMPR 1974


         Tecnazene (1,2,4,5-tetrachloro-3-nitrobenzene, 2,3,5,6-tetra-
    chloronitrobenzene, TCNB) was scheduled for evaluation by the present
    Meeting, but insufficient data on which to base recommendations were
    received. The limited information available to the Meeting is reviewed



    Absorption, distribution and excretion

         Following oral administration to rabbits at doses ranging from
    0.1 to 3 gm/animal, the major quantity of material was rapidly
    excreted in the faeces (60-78%) within three days. Quantities were
    observed in the urine (35-38%) primarily as conjugated products. At
    lower doses, 22-30% of a single oral dose was recovered in the faeces
    (Bray et al., 1953).


         Following oral administration to rabbits, isolation and
    identification of metabolites indicated that reduction (predominantly
    bacterial) of the nitro group took place in the gut. Very small
    amounts of pentachloroaniline, a mercapturic acid derivative,
    4-amino-2,3,5,6-tetrachlorophenol, a sulphate, and a glucuronide were
    excreted in the urine (Menzie, 1969; Bray et al., 1951; 1952; 1953).
    Reduction of the nitro group to the aniline derivative was observed
    in vitro with rat liver preparations incubated with tecnazene for
    three hours (Bray et al., 1953).


    Acute Toxicity

         The acute oral LD50 in the rat was approximately 7 500 mg/kg bw
    (Klimmer, 1971).

         No untoward reactions or signs or irritation were observed
    following installation of tecnazene, directly in the conjunctival sac
    of rabbits. No toxic effects were observed after tecnazene was applied
    to the shaved backs of rabbits for two successive days. Dermal
    blackening and induration were observed after six days. A dose of 500
    mg applied to the skin caused slight discoloration but no induration
    (Buttle & Dyer, 1950).

         Repeated oral administration of tecnazene (3 gm) to adult female
    rabbits resulted in no apparent adverse effects. The administration of
    an isomer (2,3,4,5-tetrachloronitrobenzene) administered in doses of
    700 mg/rabbit produced a slight anorexia persisting up to two days.
    Repeated doses of 2,3,5,6-tetrachloroaniline (1 gm/rabbit) did not
    result in any adverse effects (Bray et al., 1953).

    Short Term Studies


         A group of 24 mice were fed tecnazene (13.68%) in the diet,
    consuming 250 mg/day (10 000 mg/kg body weight/day). Mortality was
    observed in 3-4 days and this test was discontinued. Fatty
    degeneration of the liver and fatty changes in the spleen and kidney
    were noted (Buttle & Dyer, 1950).

         Groups of mice (12 mice/group) were fed tecnazene in the diet at
    levels of 0, 1 344, and 13 440 ppm for 31 days. Growth was inhibited
    at the high level. Growth was normal and no adverse effects were
    observed at 1344 ppm (equivalent to 134 mg/kg body weight/day) (Buttle
    & Dyer, 1950).


         Groups of rats (5 males and 5 females per group) were fed
    tecnazene in the diet for ten weeks at levels of 0, 800, 4000, and
    20 000 ppm. Mortality was noted at the high dose. Growth was reduced
    at 4000 ppm. No effects were noted on growth or mortality at 800 ppm,
    (Buttle & Dyer, 1950).

         Groups of rats (5 males and 5 females per group) were fed
    tecnazene at levels of 0, 200, 800, and 3200 ppm in the diet for
    twelve weeks and mated to produce an F1 generation. Five rats of each
    sex of the F1 generation were maintained after weaning on the
    respective diets for a further twelve weeks and mated to produce an
    F2 generation. Growth was slightly inhibited at the 3200 ppm dose
    level over the twelve week measurement interval in each generation.
    Fatty infiltration of the liver was also observed at 3200 ppm. No
    effects were noted at 800 ppm in any of the animals examined (Buttle,


         Groups of dogs (2 males and 2 females per group; controls - 1
    male and 1 female) were treated with tecnazene orally by capsule for
    two years at levels of 0, 3.75, 15, 60, and 240 mg/kg body weight/day
    (6 days/week). Mortality was observed at the high level and all
    animals died within the first year of the study. Growth was normal in
    all animals at 60 mg/kg. Clinical chemistry was normal at 15 mg/kg.

    The values for serum alkaline phosphatase activity were elevated at 60
    and 240 mg/kg. Microscopic changes were observed in liver, kidney, and
    bone marrow at the high feeding level. No effects attributed to the
    administration of tecnazene were noted in haematological and
    urological values or in measurement of EKG (Donikian et al., 1965).

    Long Term Studies


         Groups of rats (20 males and 20 females per group) were fed
    tecnazene in the diet for two years at levels of 0, 25, 100, 400, and
    1600 ppm. No significant effects were noted on growth, food
    consumption, clinical chemistry, haematology, or by gross and
    microscopic examination of tissues and organs. Survival of rats over
    the 104 day duration of the experiment was poor. In the control
    groups, only 2/20 males and 5/20 females lived to complete the study.
    No males were alive at the two highest doses at 104 weeks. Clinical
    chemistry values (SGPT, SGOT, etc.), determined only at 104 weeks,
    were normal in all surviving animals. As there were no animals that
    survived at the high doses, those parameters which were reduced in the
    dog study could not be evaluated (Owen et al., 1965).

    Observations in man

         Occupational dermal sensitivity in man has been reported in
    agricultural workers (Lupuknova, 1965).


         Tecnazene, one of several polychlorinated nitrobenzene isomers is
    rapidly absorbed and metabolized although the metabolic fate in
    mammals is not well defined. High doses of tecnazene are predominantly
    passed unchanged in the faeces. In mice, growth was inhibited at a
    dietary level of 13 440 ppm with no effects noted at 1 344 ppm, over a
    31 day interval. Dietary administration to rats at a dose equivalent
    to 400 mg/kg resulted in a growth reduction while 1 111 mg/kg was
    fatal within three weeks. In a long term study in rats, no effects
    were noted at 1 600 ppm in the diet although few animals survived to
    the end of the study. In dogs no effects were noted in a two-year
    study at 15 mg/kg. Slight effects in dogs were noted as an increased
    serum alkaline phosphatase at higher doses. No evidence of
    tumorgenicity was noted in the rat study. However, a complete
    evaluation of this study was difficult as survival was poor up to two
    years. Data from adequate research protocols supporting the safety of
    pesticides in food are not available with this compound. No studies
    are available relating to mutagenicity, teratogenicity, effects on
    reproduction, metabolism in mammals other than the rabbit, mechanism
    of action, or the effects on man. In the absence of significant data
    the Meeting was unable to allocate an ADI for man.


         No ADI allocated.


    Explanatory note

         Tecnazene was developed prior to 1940 for fungicidal uses and has
    been introduced for the control of Botrytis and Sclerotina in
    vegetables, Fusarium (dry rot) in potato growing and as a sprout
    inhibitor on stored potatoes.

         Registrations of 3-5% dusts and of smoke preparations have been
    recorded for a few countries, e.g. New Zealand, USA and the
    Netherlands. Some of these registrations have been phased out in later
    years, but at the same time renewed interest in the chemical has been
    reported, especially for some greenhouse cultures.

         Apart from some early residue data on the uptake of tecnazene in
    potatoes and its fate during their storage and cooking, no further
    information has been made available to the Meeting. Under the
    circumstances no recommendations for residue limits could be made
    before full information on chemical and formulated products
    specifications (including impurities, e.g. HCB), present use patterns,
    residue data from supervised trials, fate of residues in crops other
    than potatoes and in soils etc. is made available.

         Considering the lack of information, including the uncertainties
    concerning the present uses of the compound, the Meeting was unable to
    review the needs for further evaluation of tecnazene. It was agreed
    that the need for further work should be considered by the Codex
    Committee on Pesticide Residues.


    REQUIRED (if further evaluation is to be undertaken)

    1.   Adequate toxicological data.

    2.   Full information on specifications for the chemical and the
         formulated products (including impurities, e.g., HCB), present
         use patterns, residue data from supervised trials, rate of
         residues in crops other than potatoes and in soils, etc.


    Bray, H.G., Hybs, Z., Lake, H.J. and Thorpe, W.V. (1951) The
    metabolism of 2,3,5,6-tetrachloronitrobenzene and
    2,3,4,5-tetrachloronitrobenzene in the rabbit. Biochem. J., 49:lxv.

    Bray, H.G., Hybs, Z., James, S.P. and Thorpe, W.V. (1952) The
    formation of mercapturic acid from 2,3,5,6-tetrachloronitrobenzene in
    the rabbit. Biochem. J., 52:xviii.

    Bray, H.G., Hybs, A., James, S.P. and Thorpe, W.V. (1953) The
    metabolism of 2,3,5,6- and 2,3,4,5-tetrachloronitrobenzenes in the
    rabbit and the reduction of aromatic nitro compounds in the intestine.
    Biochem. J., 53:266-273.

    Buttle, G.A.H. (1974) Experiments on the chronic toxicity of
    2,3,5,6-tetrachloronitrobenzene administered to rats over three
    generations. Report submitted by Sterwin Chemicals, Inc. to F.D.A.

    Buttle, G.A.H. and Dyer, F.J. (1950) Experiments on the toxicology of
    2,3,5,6-tetrachloronitrobenzene. J. Pharm. Pharmacol., 2:371-375.

    Donikian, M., Owen, S.D., Wiland, J. and Drobeck, H.P. (1965) Oral
    administration of 2,3,5,6-tetrachloronitrobenzene to beagle dogs for
    two years. Report from Sterling Winthrop Research Institute.

    Klimmer, O.R. (1971) Pflanzenschutz und Schädlings
    - bekämpfungsmittel. Abriss liner Toxicologie und Therapie von
    Vergiftungen. Pub. Hundt-Verlag. p. 78.

    Lupuknova, K.A. (1965) Case of occupational toxicodermia caused by
    2,3,5,6-tetrachloronitrobenzene. Gigiena Truda i Prof. Zabolevaniya,
    9:56-58. (In Russian) (Chem. Abs. 63:12219h, 1965).

    Menzie, C.M. (1969) Metabolism of Pesticides. U.S. Dept. Interior. 
    Special Scientific Report. Wildlife No. 127:302.

    Owen, S.D., Fabian, R., Donikian, W.J. and Drobeck, H.P. (1965) Oral
    administration of 2,3,5,6-tetrachloronitrobenzene in the diet to
    albino rats for two years. Report from Sterling Winthrop Research
    Institute. (Unpublished).

    See Also:
       Toxicological Abbreviations
       Tecnazene (EHC 42, 1984)
       Tecnazene (HSG 12, 1988)
       Tecnazene (Pesticide residues in food: 1978 evaluations)
       Tecnazene (Pesticide residues in food: 1981 evaluations)
       Tecnazene (Pesticide residues in food: 1994 evaluations Part II Toxicology)