Individual monographs were prepared on ferbam, maneb, nabam, thiram,
    zineb and ziram by the 1965 and 1967 Joint Meetings (FAD/WHO, 1965,
    1968), and on manoozeb by the Meetings of 1967, 1970 and 1974
    (FAO/WHO, 1968, 1971, 1975). The latter monograph also contains data
    relating to the other ethylenebisdithiocarbamates (EBDC) maneb,
    metiram, nabam and zineb. Separate monographs on the dithiocarbamate
    fungicides as a group were also prepared at the 1970 and 1974

    At the 1974 Joint Meeting, recommendations were made for temporary
    tolerances for ethylenediamine and ethylenethiourea (ETU) derived from
    Mancozeb on a number of commodities, and the further work required was
    indicated. The following monograph addendum reviews available
    information on dimethyl- and ethylenebisdithiocarbamates. The
    propylenebisdithiocarbamate propineb has not been evaluated previously
    and is therefore the subject of a separate monograph.



    The dimethyl dithiocarbamates possess similar metabolic and
    toxicological potential where structures are similar. Thus, ferbam and
    ziram were considered to be sufficiently alike to be grouped together.
    The concerns relating to reactions with nitrite to form nitrosamines
    and the potential for teratogenicity expressed by previous meetings
    were considered. The present Meeting determined that an ADI for humans
    could be established.

    In the case of thiram, the difference in structure was sufficient to
    warrant separate consideration. Thiram is also teratogenic at high
    dose levels. In addition, data indicated that a diet supplying 0.015
    mg thiram daily to rats resulted in weight loss, nervous disturbances
    and severe anaemia. These data were available in summary form only. No
    haematological data were available to the Meeting. Since in other
    studies much higher dose levels did not result in significant weight
    gain changes, the Meeting determined that the no-effect level should
    be derived from the more extensive data available in a long-term
    study. However, concerns relating to haematology were deemed to
    require investigation and, hence, a temporary acceptable daily intake
    for humans was established for this compound.


    (a) FERBAM

    Level causing no toxicological effect

         Rat: 250 mg/kg in the diet, equivalent to 12.5 mg/kg bw

         Dogs 5 mg/kg bw


         0-0.02 mg/kg bw

    (b)  ZIRAM

    Level causing no toxicological effect

         Rat:250 mg/kg in the diet, equivalent to 12.5 mg/kg bw

         Dog: 5 (mg/kg bw)/day


         0-0.02 mg/kg/bw

    (c) THIRAM

    Level causing no toxicological effect

         Rat: 48 ppm in the diet, equivalent to 2.5 mg/kg bw

         Dog: 5 (mg/kg bw)/day


         0-0.005 (mg/kg bw)/day


    (a)  NABAM

    Nabam is sodium ethylenebisdithiocarbamate. Like other fungicides of
    this class, it decomposes and is degraded to ETU and ethylenediamine
    (EDA). It was evaluated by previous Joint Meetings and a temporary ADI
    for humans was allocated in 1974.

    Nabam is the most acutely toxic of this class of compounds and is
    goitrogenic. The Meeting was concerned at the relatively high acute
    toxicity of this compound and as it was unaware of any work currently
    in progress, it was unable to recommend an ADI for humans or to
    recommend the retention of the existing temporary ADI for humans.

    However, it is recognized that nabam is used in agriculture only in
    conjunction with zinc sulphate to form zineb before spraying.


    The Meeting was aware of further work in progress and for this reason
    decided to retain the existing temporary ADI for humans for a period
    of two years at the present level of 0-0. 005 mg/kg. This ADI for
    humans applies to mancozeb, maneb and zineb individually or as the sum
    of any or all of these.


    See separate monograph on this compound.



    Additional data from supervised trials involving several
    ethylenebisdithiocarbamates ware available to the Meeting from several
    sources; these are summarized in Table 1.


    The requirements for further work on EBDC's published by the 1974
    Joint Meeting included:

    1. Residue studies in which both the ethylenediamine moiety and
    ethylenethiourea (ETU) are separately determined.

    2. Further studies on the fate of residues during the preparation and
    processing of foods with particular reference to their conversion to

    Information concerning these requirements was made available to the
    Meeting. It appears that the first requirement is not likely to be met
    because of inadequacies established in the analytical method
    previously used to determine the EBDC residues as ethylenediamine
    (Anonymous, 1977). Observed deficiencies included, the occurrence of
    variable but high 'blank' values, low recovery of ETU added to crop
    materials, and progressively lower recoveries with time from milk.
    Data from treated samples were therefore considered to be unreliable
    and use of the method should be discouraged. The growth of interest in

        TABLE 1. Residues of mancozeb, maneb and zineb found in
    various crops in supervised trials

                                   Pre-harvest            Residues found (mg/kg)
    Compound        Crop        interval (days)        Range                Mean                Source


    Mancozeb        Apples           22-44            0.6-3.0               1.5                 Anonymous 1977

                                      28                 -                  3.1}                IUPAC 1977
                                      42                 -                  1.7}

                    Carrots            -              0.1-0.2               0.1}                Phillips et al.
                                       -              0.2-0.7               0.5}                   1977

                    Grapes           0-30             1.9-5.1               3.7                 Canada 1977

                    Spinach            -              0.9-2.5               1.8}                Phillips at al.
                                       -              24-123                54 }                   1977

                    Tomatoes          3-5             0.3-1.6               0.7                 Anonymous 1977

                                       -              0.1-0.6               0.3}                Phillips at al.
                                                      1.4-2.3               1.9}                   1977

                    Wheat            28-47             0-0.4                0.15                Anonymous 1977

    Maneb           Cantaloupes       1-5            0.4-2.3                1.1}
                    Cucumbers         1-7            0 1-0.68               0.3}
                    Potatoes         1-14              <0.1                 <0.1}               Pease & Holt
                    Summer squash     1-7           < 0.1-0.56              0.2}                   1977
                    Tomatoes          1-7            0.35-4.0               1.6}

    TABLE 1 (Continued)
                                   Pre-harvest            Residues found (mg/kg)
    Compound        Crop        interval (days)        Range                Mean                Source


                                     7-14            0.47-0.83              0.6                 Canada 1977

                                       -              1.5-2.3               2.0                 Phillips at al.

                    Grapes            14              2.3-7.5               4.6}                Montedison 1977
                                      24              1.2-5.9               3.4}

    Zineb           Pears             21                 -                  1.0                 Canada 1977
    (Residues determined as CS2 and expressed as parent compound)

    ETU residues has also led to a renewed interest in the CS2 evolution
    methods should give a better measure of the sum of those compounds
    present which might be converted to ETU. The improved ethylenediamine
    method of Newsome (1974) is more effective in measuring EBDC residues
    but it excludes ETU and other components of the residue mixture.

    The requirement for information regarding conversion to ETU has been
    responded to in an unusual manner. The current position regarding many
    aspects of ETU has been reviewed by the Commission on Terminal
    Residues of the Applied Chemistry Division of the International Union
    of Pure and Applied Chemistry (IUPAC, 1977). Their Special Report
    deals with analytical methods; the chemistry of ETU; the dynamics,
    transformation and occurrence of ETU residues; and the effects of
    cooking and processing food containing ETU residues. The following
    conclusions were recorded:-

         1.   ETU occurs an a primary reaction product of the EBDC

         2.   ETU is present in commercial formulations in varying amounts
              (0.02-2%). The amount increases on storage under warm and   
              humid conditions.

         3.   Environmental degradation (metabolism in plants, soils,
              animals and water) of the EBDC fungicides also leads to ETU

         4.   There is no evidence for the persistence or bioaccumulation
              of ETU residues in plants, soils or water, although ETU is  
              detected as a metabolite and accumulates in the thyroids of

         5.   Currently, there are several adequate methods for the
              determination of ETU residues, however, there are no simple
              procedures that are universally applicable.

         6.   Monitoring data confirm the frequent presence of EBDC
              residues in or on raw agricultural crops treated using good
              agricultural practices. Generally, residues of EBDC do not  
              exceed nationally recommended tolerances 1 - 7 PPM.

         7.   A substantial portion of the EBDC residue may be removed
              from the raw agricultural crop following a simple washing   
              procedure. These procedures remove approximately from 30 -
              90% of the residue.

         8.   Monitoring data confirmed the presence of ETU residues in or
              on certain raw agricultural crops. Generally, these residues
              were less than 0.1 ppm. most approaching the lower limits of
              analytical detection (0.01 ppm).

         9.   ETU is found in most heat processed foods, where EBDC
              residues were found prior to processing. Heat processing has
              been shown to convert from 16 to 23% (weight basis) of the  
              EBDC residues to ETU. Consequently, the concentration of ETU
              my be higher in processed foods than in the raw agricultural

         10.  Current chemical data do not preclude the contained use of
              EBDC fungicides in good agricultural practices.

    These conclusions were endorsed by the FAC Panel of Experts.

    The IUPAC Commission also made the following recommendations for
    further action:-

         1.   That the acceptable average daily intake of ETU and EBDO
              should be calculated immediately.

         2.   Analytical methodology for ETU and ETU-forming compounds
              should be simplified to expediate monitoring programs.
              Simple, rapid and specific methods are required. An
              international collaborative study should be initiated.

         3.   Toxicological significance of residues reported in
              monitoring data should be determined by competent
              international bodies.

         4.   Further studies of the degradation and metabolism of EBDC
              and ETU in crops and animals should be conducted.

         5.   Further data on the conversion of EBDC residues to ETU in
              various food processing procedures should be developed.
              Studies to minimize the formation of ETU during food
              processing should be initiated.

    These recommendations were discussed by the Joint Meeting and were
    generally accepted; recommendation 5 in particular was endorsed.


    Some data on residues of dithiocarbamate fungicides found in Sweden
    and the Netherlands were considered. The former data are summarized in
    Table 2 (Winell, 1975). Residues were determined by CS2 evolution
    and expressed as zineb. Only results at 1.0 mg/kg or above are
    detailed here; these represent 27 out of a total of 617 samples
    examined. Data available from the Netherlands (1977) showed that of 13
    samples of endive and lettuce examined, none exceed 2 mg/kg as zineb.
    Analyses of 1031 samples of varied fruits and vegetables specifically
    for thiram residues (Netherlands, 1977) showed only 14 instances in

    which the national tolerance of 3.8 mg/kg was exceeded. Of these, 12
    (out of 45 examined) were samples of strawberries (ranging from 4.2 to
    14.6 mg/kg: the other two were one lettuce (out of 590) and one
    currant sample.

        TABLE 2. Dithiocarbamate residues (1.0 mg/kg or greater)
    found in crops in Sweden, (Winell. 1975)


    Crop                     Country        Residue found (as zineb, mg/kg)

    Apples                   USA                          1.0
    Banana (peel)            Honduras                     3.5
    Cucumbers                Netherlands               1.0, 1.2
    Grapes                   Italy                     1.0, 2.4
    Lettuce                  Belgium                      3.7
                             Netherlands               1.8, 9.9
    Melon (peel)             Israel                       1.7
    Peaches                  Italy                     2.6, 2.7
    Pears                    Australia                    1.4
                             Italy           1.1, 1.2, 1.2, 1.4, 1.5, 2.5
                             Sweden                  1.0, 1.0, 1.1
    Potatoes                 Sweden             1.0, 1.0, 1.0, 1.3, 2.2

    A gas-liquid chromatographic procedure for the determination of traces
    of ethylenethiourea in fresh vegetables, fruits, milk and cooked foods
    (Onley et al., 1977) has been successfully collaboratively studied
    (Onley, 1977). The method is designed to determine ETU without
    interference from ethylenebisdithiocarbamates and has been adopted as
    an "Interim Official First Action" procedure. Two extraction
    procedures are described, before and after a cooking process. The
    cooking step is included to permit assessment of ETU residues which
    could result from the conversion of EBDC fungicides that may also be
    present on the raw commodities.

    A new method which does not require the formation of a derivative of
    ETU prior to gas chromatography has been proposed by Otto at al.
    (1977). Plant material is extracted with methanol in the presence of
    sodium ascorbate. After clean up by hexane:water partition, alumina
    column chromatography of the aqueous phase and subsequent
    dichloromethane water partition, the ETU is measured directly by GLC
    with a flame photometric detector in the sulphur mode. A limit of
    detection of 0.01 mg/kg is claimed.


    Mancozeb and other ethylenebisdithiocarbamates (EBDCs) were considered
    by the 1967, 1970 and 1974 Joint Meetings and further information had
    been requested concerning the occurrence of ethylenethiourea as a

    Information made available has indicated that the use of the
    ethylenediamine analytical procedure was inefficient as an indicator
    of residues of EBDCs and should be discarded. This would also mean the
    withdrawal of the temporary tolerances for this compound recommended
    by the 1974 Joint Meeting and the reversal of the decision to base
    maximum residue limits on ethylenediamine content. Analytical methods
    based on CS2 evolution remain the only pragmatic procedures for the
    general estimation of EBDC residues. The need for specific (or
    group-specific) analytical methods remains unfulfilled.

    The need to determine ETU arising from the use of
    ethylenebisdithiocarbamates has been confirmed (see also monograph on
    propineb); the temporary residue limits recommended in 1974 for ETU
    are maintained as guideline levels. A recent collaborative study has
    established a procedure for the determination of ETU residues in a
    range of foods.

    Very limited data were available concerning residues of the
    dimethyldithiocarbamates ferbam and ziram or of thiram.


    The temporary tolerances for ethylenediamine recommended by the 1974
    Joint Meeting are withdrawn. The temporary maximum residue limits for
    ETU are maintained as guideline levels, pending further information.

    The importance of this group of fungicides is well recognized and
    although it is not possible to recommend maximum residue limits for
    the individual compounds (because of analytical considerations), It
    would be helpful to set some general temporary maximum residue limits
    to cover members of the dithiocarbamate fungicides as a group. From a
    further study of data reported previously and some additional data
    available to the meeting (including that on propineb), the following
    limits appear to be adequate to cover the likely residues arising from
    the use of single dithiocarbamate compounds on the crops listed. The
    limits refer to residues, determined by CS2 evolution and expressed
    as CS2, derived from ferbam, mancozeb, maneb, propineb, thiram,
    zineb and ziram.

    These limits are based on data arising from supervised trials in which
    alkylenebisdithiocarbamates were used; coexisting residues of thiram
    (or ferbam or ziram) from other treatments of the same crop could lead
    to these levels being exceeded, especially on apples, lettuce,
    tomatoes and strawberries. In such cases, separate analysis should be
    made by the available method which is specific for thiram (AOAC,

             Commodity         Limits (as CS2) mg/kg

         Blackcurrants, celery,
         grapes, red currants                    5

         Apples, peaches, pears,
         strawberries, tomatoes                  3

         Bananas (whole), cherries,
         endive, lettuce, melons,
         plums                                   1

         Beans (in pod), carrots,
         cucumbers                               0.5

         Wheat                                   0.2

         Bananas (pulp),
         potatoes                                0.1


    (a) Dithiocarbamates in general

    REQUIRED (by July 1980)

    1. A comprehensive survey of the use patterns of thiram, ferbam and

    2. Data on residues of thiram, ferbam and ziram from supervised

    3. Data on residues of dithiocarbamates from crops grown under glass.

    (b) Dimethyl dithiocarbamates

    REQUIRED (by July 1980)

    Further studies to investigate the haematological effects of thiram.

    (c)  Ethylene bisdithiocarbamate

    REQUIRED (by July 1980) (in addition to the toxicological information
    listed in FAO/WHO 1975, P. 34)

    1. Further data on the conversion of EBDC to ETU in various food
    processing procedures.

    2. Studies of procedures to minimize the formation of ETU during food


    Anonymous (1977) The ethylenediamine residue analytical method. Report
    received from Rohm and Hass Co. (unpublished).

    ACAC (1975) "Official methods of analysis", 12th Ed., 551-552.

    Canada (1977) Data received from the Canadian Government

    FAO/WHO (1968) 1967 evaluations of some pesticide residues in food.
    FAO/PL/1967/M/11/1; WHO/Food-Add./68:30.

    FAO/WHO (1971) 1970 evaluations of some pesticide residues in foods
    PAO/AGP/1970/X/12/1; WHO/Food Add./71.42. p. 269-283 and P.407 - 422

    FAO/WHO (1975) 1974 evaluations of some pesticide residues in food.
    FAO/AGP/19741/M/11; WHO Pesticide Residue Series, No. 4.

    IUPAC (1977) Ethylenethiourea. Pure and Appl. Chem., 49:675-689.

    Montedison Co. (1977) Residues of ethylenebisdithiocarbamates and
    ethylenethiourea in grapes and wine (unpublished).

    Netherlands (1977) Data received from the Netherlands Government

    Newsome, W.H. (1974) A method for determining
    ethylenebis(dithiocarbamate) residues in food crops as
    bis(trifluoroacentamido)ethane. J. Agr. Food Chem.p 22(5): 886-889.

    Onley, J.H, Giuffrida, L., Ives, N.F., Watts, R.R. and Storherr,
    R.W. (1977)  Gas-liquid chromatography and liquid chromatography of
    ethylenethiourea in fresh vegetable crops, fruits, milk and cooked
    foods. J. Assoc. Off. Anal. Chem.# 60:1105-1110.

    Onley, J.H. (1977) Gas-liquid chromatographic method for determining
    ethylenethiourea in potatoes, spinach, apple sauce, and milk;
    collaborative study. J. Assoc. Off. Anal, Chem., 60:1111-1115,

    Otto, S., Keller, W., and Drescher, N. (1977) A new gas
    chromatographic determination of ethylenethiourea residues without
    derivatisation. J. Environ. Sci. Hlth., B 12(3):179-191.

    Pease, H.L. and Holt, R.F. (1977) Manganese ethylenebisdithiocarbamate
    (meneb)/ethylenothiourea (ETU) residue studies on five crops treated
    with ethylenebisdithiocarbamate (EBDC) fungicides. J. Agric. Food
    Chem., 25:561-567.

    Phillips, W.F., Grady, M.D. and Freudenthal, R. (1977) Effects of food
    processing on residues of two ethylenebisdithiocarbamate (EBDC)
    fungicides and ethylenethiourea (ETU). Environmental Health Effects
    Research Series, EPA-600/1-77-021, EPA, North Carolina, USA.

    Winell, B. (1975) Ditiokarbamatrester i frukt bär, grönsaker och
    potatis. Vär föda No. 2, 1-9.

    See Also:
       Toxicological Abbreviations
       Dithiocarbamate Fungicides (AGP:1970/M/12/1)