sec - BUTYLAMINE           JMPR 1978


         In 1975 the Joint Meeting (FAO/WHO 1976b) evaluated
    sec-butylamine. A temporary ADI was allocated and some temporary
    MRLs were recommended. In 1977 information on the fate of
    sec-butylamine in livestock when citrus pulp and molasses containing
    residues are used as components in their ration was evaluated (FAO/WHO

         Of the remaining work or information required, some information
    on uses on fruits other than citrus was considered in 1977. Since
    then, information has been supplied from Scotland and Ireland on the
    use and fate of sec-butylamine applied to potatoes: this is evaluated
    in the following monograph addendum.



         No toxicological data bearing on the concerns expressed by the
    1975 Meeting were received. A re-evaluation of the long-term
    rat-feeding study, including a microscopic examination of tissues, was
    made to consider the suggestion of an incidence of thyroid light-cell
    adenoma. The Meeting was also made aware of similarities between
    light-cell tumours in rats and thyroid tumours in humans. Although
    there was no evidence from that re-evaluation to suggest a
    carcinogenic potential for sec-butylamine, it was felt that the
    study was of borderline value for an adequate carcinogenic bioassay.
    The Meeting felt that further information on the carcinogenic
    potential was needed. No bioassays for mutagenic activity which would
    bear on this question and which were requested by the 1975 Meeting
    were reported. Concern was raised on the potential for the formation
    of a nitrosated derivative. As a result of these concerns, the Meeting
    estimated a temporary ADI at a lower level.


    Level causing no toxicological effect

           Rat:      686 ppm base (1250 ppm acetate salt) in the diet
                     equivalent to 35 mg base/kg bw (63 mg acetate salt)
                     kg bw

           Mouse:    69 mg base/kg bw/day (125 mg acetate salt) kg bw/day

    Estimate of temporary acceptable daily intake for man

           0 - 0.1 mg base/kg body weight




         Since 1971 sec-butylamine has been widely used in Scotland, and
    more recently in Ireland, for treatment of seed potatoes, giving good
    control of gangrene caused by Phoma exigua var. FAVEATA and skin
    spot due to Oospora pustulans. Some control of silver scurf disease
    (Helminthos porium solani) is also obtained (Graham and Hamilton,
    1970; Graham et al., 1973, 1973b, 1975; Quinn et al., 1976; Graham,

         Recently, limited approval was extended to allow the sale of
    those treated potatoes which are too small or too large for seed
    purposes for human consumption and animal feed.

         Potato-tubers are fumigated with sec-butylamine generated as a
    vapour from the base. The rate is 200 mg/kg and application should be
    made within 14 days of harvest. Air is charged with the vaporised
    sec-butylamine while it is re-circulated through the potatoes for 30
    minutes and then re-circulation of the charged air continued for a
    further two hours.

         In general, fumigation does not have any substantial effect on
    the growth pattern or the yield of the crop obtained from treated
    seeds. However the use of sec-butylamine greatly reduces the loss of
    seed potatoes during storage. Without treatment the loss can exceed
    60% with some varieties (Quinn at al., 1976).

    Other uses

         Although sec-butylamine has been used experimentally on
    commodities other than citrus and potatoes there was no evidence that
    any of these treatments has been accepted commercially.


         Having demonstrated effectiveness against gangrene and skin spot
    Graham and Hamilton (1970) carried out trials in which 3 varieties of
    potatoes were fumigated in a specially constructed chamber holding
    5000 kg of potatoes, treatment being carried out within 2 days of
    harvest and care being taken to ensure good distribution throughout
    the stack. The air/fumigant mixture was blown through the perforated
    floor of the chambers.

         The potatoes were sampled from the top and bottom of the stacks
    (1.5 m high). The samples were analysed by the gas-chromatographic
    method of Day et al., (1968) but without a carbon tetrachloride wash.

         Considerable variation was found in the residues in individual
    potatoes, even in adjacent tubers. This was almost certainly due to
    the condition of the skin since higher residues were found in immature
    tubers and in those whose skin was damaged. To reduce this variation,
    sound quarters were taken from each of four tubers of fairly uniform
    size for each analysis.

         Typical residues in potatoes treated in the 5-tonne chambers
    where the fumigant was introduced over 30-40 minutes and re-circulated
    for a further 2 hours are shown in Table 1. Good distribution with a
    dosage of 200 mg/kg was achieved, but at 50 mg/kg most of the residue
    was confined to the lower tubers indicating this dose to be
    insufficient for equal distribution.

         Commercial potato stores of large capacity fitted with internal
    re-circulation systems are adaptable for fumigation and Graham et al.,
    (1975b) reported trials in which 35 tonne lots were fumigated in such
    a store. The degree to which equal distribution of sec-butylamine
    throughout the bulk of tubers took place was determined by residue
    analysis. Results are given in Table 2. The residue levels in samples
    taken at the end of fumigation (Nos. 1-17), showed there was good
    horizontal distribution at the top of the bin. Vertical distribution
    also seemed to have been satisfactory because samples taken from
    various positions at the top of the bin had a mean residue level of
    161 mg/kg whereas 196 mean level of 196 mg/kg was found on samples
    taken from the bottom near the duct.

         Samples in mesh bags were buried in the bulk at the time of
    filling the store. These were recovered 5 months after fumigation and
    analysed. Some reduction in the residues had occurred but the mean
    levels of 111, 88 and 100 mg/kg in the top, middle and bottom
    confirmed that the gas distribution had been satisfactory.

         Graham at al., (1973a) recognized that the decline in
    effectiveness of fumigation which occurs when the treatment is delayed
    following harvest was due to the skin and damaged areas becoming
    increasingly impervious to the gas as a result of physico-chemical
    changes after lifting. It was also suggested that the fungus might
    have penetrated to depths in the tuber which the sec-butylamine
    could not reach in sufficient concentration to kill the organism.
    However, the need to treat tubers so soon after lifting presents
    practical problems, especially when chemicals that many only be
    applied to seed potatoes are used because separation of seed and ware
    (table) potatoes has then to be done quickly, often while growers are
    still lifting crops. Growers prefer to store the mixture of seed and
    ware, separating them up to several months later. Another reason for
    delaying sorting is that latent infections associated with the tuber
    become activated by damage during grading. Fumigation after grading
    was shown to be much less effective than a similar treatment carried
    out on the freshly lifted tubers.

        TABLE 1. Residues of sec-butylamine in potatoes fumigated within 2 days
             of lifting in a 5-tonne prototype fumigation chamber

    Cultivar            Dose (mg/kg)    Same position     Residue (mg/kg)
                                        in chamber
    Redskin 1             200           top                   194
                                        bottom                182

    Majestic 1            200           top                   103
                                        bottom                113

    Redskin 2             200           top                    92
                                        bottom                160

    King Edward 1         200           top                    92
                                        bottom                 90

    Kind Edward 2          50           top                    12
                                        middle                 39
                                        bottom                 32

    Redskin 3              50           top                     2
                                        middle                 11
                                        bottom                 23

    TABLE 2. Residues in a 35 tonne bulk fumigated soon after lifting
             (Pentland Crown tubers) (Graham et al., 1973b)
                                                                   Range of     Mean
    Sample    Position          Time of sampling                   residues     residue
    no.       in bin 4                                             (mg/kg)      (mg/kg)
    1-2       top layer         after 50% of dose applied          2.3-6.8        4.6

    3-4       top layer         after 100% dose applied            57-114         86

    5-6       top layer         after 1 h further recirculation    103-112        108

    7-8       duct below bin    at end of fumigation               156-236        196

    9-17      top layer         at end of fumigation               124-184        161

    18-21     top layer         at unloading of bin                95-122         111

    22-23     middle layer      at unloading of bin                64-113         88

    26-30     bottom layer      at unloading of bin                58-130         100
         Graham et al., (1975) in the course of experiments to determine
    the feasibility of delaying fumigation until the ware potatoes had
    been sorted from the bulk determined the residue of sec-butylamine
    in tubers after hand and mechanical sorting. The data are summarized
    in Table 3. These potatoes had been fumigated at the rate of
    200 mg/kg.

         Graham (1978) provided information on residue levels measured in
    several other trials in which sec-butylamine was applied in the
    vapour phase at the rate of 200 mg/kg. There results are summarised in
    Table 4.

         Eades et al., (1978) reported results of the analysis of samples
    taken from 50 kg jute sacks fumigated at the rate of 200 mg/kg. These
    are given in Table 5. Some analyses were done in triplicate. The
    variation between individual samples is noticeable.


    In plants

         In 1968, potatoes which had been grown from seed tubers treated
    at 140 mg/kg three days after lifting in 1967, were harvested. In 1969
    crops were harvested from seed treated at levels of 200, 500 and 1000
    mg/kg three days after lifting in 1968. In 1970, crops were harvested
    from seed treated at 200 mg/kg three and fourteen days after lifting
    in 1969. Results of the analysis of all these crops and untreated
    material from the same source are given in Table 6 (Graham et al.,
    1973). Eades et al., (1978) reported from 0 to 0.36 mg/kg in the
    progency of single tubers fumigated at 200 mg/kg. This value had been
    corrected for background contamination.

         The residues found crops grown from treated seed are very small
    and are generally not greatly different from those found in untreated
    material, even when the mother tubers had been treated at five times
    the recommended dosage. There is, therefore, no significant
    translocation of the chemical to daughter tubers, so that there is no
    hazard to consumers from crops grown from treated seeds.

    In animals

         General studies designed to evaluate the effect and fate of
    sec-butylamine fed to dairy cows as a residue in their ration were
    evaluated in 1977 (FAO/WHO 1978b).

    In storage

         Graham et al., (1973a) reported that there was some reduction in
    residue when potatoes were stored under ventilated conditions, such as
    in oven trays. However, the variation between individual tubers made
    it difficult to establish this with certainty. Substantial residues
    were still present after many months storage.

         Graham et al., (1973b) showed that some reduction occurred in
    large stacks held for 5 months but the average concentration was still
    about 100 mg/kg.

    In processing

         Graham et al., (1973a) found that 44-75% of the residue was
    removed by peeling potatoes in the usual manner, which removes 10-12%
    of the weight of the whole tuber. The distribution of the residues
    between whole tuber flesh and peel is given in Table 7. When the
    treatment is delayed until the potatoes have been in store for a
    longer period there is less penetration: 50-84% of the residue was
    removed by peeling potatoes stored for periods up to 14 weeks before
    fumigation (Graham et al., 1975; Table 3).

         Graham et al., (1973a) found that 24-45 of the residues in potato
    flesh were removed by boiling and slightly more by crisping (Table 8).
    There are significant losses converting unpeeled potatoes into
    part-cooked potato chips (Graham 1978). Data are given in Table 9.


         No residue figures are available on samples taken at the point of
    retail sale but some of the figures given in Tables 4 and 9 are from
    potatoes intended for consumption following processing.

         When treated potatoes are sorted to remove tubers which are
    either too small or too large for use as seed only about 10% of the
    bulk is normally diverted for ware (table) use. This greatly reduces
    the likelihood of significant quantities of treated potatoes being
    used as human food.


         These residue data involving the experimentation of more than
    1000 samples, were all obtained by the method of Day et al., (1968) as
    modified by Graham et al., (1973). The latter modification consists of
    omitting the carbon tetrachloride wash. It gave a recovery greater
    than 95% and a limit of determination of 0.05 mg/kg (Graham 1978).

         Results were from the analysis of a sample comprising one quarter
    from each of four sound tubers of uniform size. The potatoes were not
    washed or peeled before analysis, but any surplus adhering soil was


         The Meeting is not aware of any national MRLs having been
    established for sec-butylamine residues in potatoes.


         For a number of years the use of sec-butylamine has been
    approved in Scotland and Ireland for the treatment of seed potatoes
    against a number of fungal diseases. Recently limited approval was
    extended to allow the sale for human consumption and animal feed of
    those treated potatoes which are too large or too small for seed
    purposes. The fungicide is applied by fumigation within 14 days
    following harvest.

         Extensive studies in Government research stations have followed
    the distribution of the fungicide among potatoes in storage, the
    effects of various factors on the retention of residues and their fate
    following processing and cooking. The bulk of the residue is in the
    outer layer and is removed by peeling. Up to half of that remaining is
    removed by cooking.

         The method of analysis used for citrus is applicable to potatoes
    as well as citrus and has been used successfully in monitoring
    programmes. The limit of determination is 0.05 mg/kg.


         Because of the limited need to use sec-butylamine on potatoes
    and the limited distribution of treated potatoes in international
    trade, no recommendation is made.


    Required (by 1981)

    1.   Further studies to resolve the question of carcinogenic risk.


    1.   Quantitative metabolic studies to determine if metabolites in
         test animals are the same as those in food plants and animals.

    2.   Information on the formation and, if found toxicity of potential
         nitrosated derivative.

    3.   Mutagenicity studies with techniques currently available.

    4.   Clinical and metabolic observations in humans.

        TABLE 3. Residues in 5 tonne bulks fumigated after periods of storage of up to 14 weeks
             (Graham et al., 1975)


    Cultivar           Grading       Number of        Residue       Residue      Calculated      Residue
                       method        days elapsed     in flesh      in peel      residue in      removed
                                     between          (mg/kg)       (mg/kg)      whole tuber     by peeling
                                     grading and                                 (mg/kg)         (mg/kg)

    1. Bintje          hand              1               1             37             5             75
                       riddle            1               7             71            14             54
                       riddle            7               5             41             9             50

    2. Marie Peer      hand              1               5            109            22             79
                       riddle            1              10            184            31             70
                       riddle            7               7             82            15             59
                       spool             1               8            173            30             74
                       spool             7               5             67            13             66

    3. Pentland        hand              1               3             89            13             80
       Squire          riddle            1              12            189            30             66
                       riddle            7               2             57             9             84
                       spool             1               7            139            22             75
                       spool             7               4             75            10             68

        TABLE 4. Residues of sec-butylamine measured in potatoes from various trials
             (Graham 1978)

    Type of storage     Quantity       No of samples       Range of        Mean
                        (tonnes)                           residues        residue
                                                           (mg/kg)         (mg/kg)

    Bulk                  250               20              2-96             34
    Bulk                  150               31              1-138            30
    Bulk                  100               25              2-107            32
    Bulk                  150               20              2-142            57
    Bulk                   80               42              1-256            83
    Pallet Boxes           30               30              1-133            42
    Pallet Boxes           11               12              45-170          101
    Pallet Boxes           20               20              70-242          117
    Bulk                   30               15              2-44             21
    Bulk                   30               26              1-137            33

    TABLE 5. sec-butylamine levels in fumigated seed potatoes (Eades et al., 1978)


    Sample no.                    sec-butylamine, mg/kg

    1                             159

    2                             18

    3                             24, 16, 5 (mean 15)

    4                             97

    5                             53

    6                             37

    7                             199

    8                             158, 80, 179 (mean 139)

    9                             80

    10                            255, 161, 132 (mean 183)

    TABLE 6. Residues of sec-butylamine in crops grown from fumigated seed tubers

    Year     Treatment of seed     Number of     Number of     Range of       Mean
             tubers                cultivars     stocks        residue        residue
                                   used          used          (mg/kg)        (mg/kg)
    1968     140 mg/kg                 2            2          0.05            0.05
             Nil                       2            2          0.05            0.05

    1969     200 mg/kg                 3            4          0.04-0.12       0.08

             500 mg/kg                 1            1          0.09-0.16       0.14

             1000 mg/kg                1            1          0.05-0.11       0.08

             Nil                       3            4          0.03-0.11       0.07

    1970     200 mg/kg (3 days)        2            2          0.01-0.10       0.05

             200 mg/kg (14 days)       2            2          0.01-0.06       0.03

             Nil                       2            2          0.01-0.04       0.03

       Limit of detection 0.01 mg/kg

    TABLE 7. Residues in 5-tonne bulks fumigated soon after lifting (Graham et al, 1973)

    Cultivar            Residue in       Residue in       Calculated       Residue
                        flesh (mg/kg)    peel (mg/kg)     residue in       removed by
                                                          whole tuber      peeling (%)
    Redskin 1                8              193              28              73
    Majestic                13              294              48              75
    Redskin 2               24              374              53              58
    Kind Edward 1           28              508              66              60
    King Edward 2           63              688             130              57
    Redskin 3               16              365              45              66
    King Edward 3           33              244              55              44
    King Edward 4           22              192              40              50
    Pentland Crown 1        24              471              62              64
    Pentland Crown 2        23              420              56              70

    TABLE 8. Effect of cooking on residues of sec-butylamine in fumigated potatoes
             (Graham et al., 1973a)


    Treatment and             Residue in           Residue in         Residue removed
    cultivar                  uncooked flesh       cooked flesh       by cooking (%)
                              (mg/kg)              (mg/kg)

    Cooking by boiling
    Redskin 1                    18.8                10.3                  45
    King Edward 1                42.4                26.1                  39
    Majestic 1                   53.0                37.0                  30
    Majestic 2                   20.0                15.3                  24
    King Edward                  10.0                 5.9                  41
    Pentland Crown 1             24.0                15.1                  37
    Pentland Crown 2             14.1                 8.4                  40

    Cooking by crisping
    King Edward 1                63.0                38.0                  40
    King Edward 2                39.0                16.5                  58
    Redskin 1                     7.8                 4.2                  46
    Redskin 2                    16.5                10.1                  39

    TABLE 9. Effect of industrial processes on the level of sec-butylamine
             residues in potatoes and potato products


                                        Residue, mg/kg
    Description of sample         Trial 1             Trial 1

    Unpeeled potatoes               76                   32

    Peel potatoes                   19                   24

    Peel                            48                   79

    Waste pieces                    60                   6.8

    Chips - freshly cut             1.2                  5.7

    Chips - blanched                6.8                  6.0

    Chips - part fried              8.4                  7.2


    Day, E.W., Holzer, F.J., Tepe, J.B., Echert, J.W. and Kolbezen,
    (1968)         M.J. Determination of sec-butylamine residues in
                   fruit. J. Ass. Off. Anal. Chem. 51: 39-44.

    Eades, J.F., Neville, C., Rice, B. Residues of sec-butylamine in
    (1978)         fumigated seed and the progeny of fumigated seed.
                   Report of the Agricultural Institute, Carlon, Ireland.

    FAO/WHO sec-butylamine. 1975 evaluations of some pesticide
    (1976)         residues in food AGP:1975/M/13 FAO Rome or WHO
                   Pesticide Residue Series No. 5. WHO Geneva P. 59.

    FAO/WHO sec-butylamine.1977 evaluations of some pesticide
    (1978)         residues in food. AGP:1977/M  FAO Rome.

    FAO/WHO 1977 evaluation of some pesticide residues in food.

    Graham D.C. Submission of residues of sec-butylamine in potatoes.
    (1978)         Letter from Department of Agriculture and Fisheries for
                   Scotland, Edinburgh (22 Aug. 1978).

    Graham D.C. and Hamilton, G.A. Control of potato gangrene and skin
    (1970)         spot diseases by fumigation of tubers with
                   sec-butylamine. Nature, London 227: 297-298.

    Graham, D.C., Hamilton, G.A., Quinn, C.E. and Ruthven, A.D. Use of
    (1973a)        2-aminobutane as a fumigant for control of gangrene
                   skin spot and scurf diseases of potato tubers. Potato
                   Res. 16: 109-125.

    Graham, D.C., Hamilton, G.A., Nash, M.J. and Lennard, J.H. Fumigation
    (1973b)        of bulk-stored potatoes with 2-aminobutane for control
                   of gangrene, skin spot and silver scurf diseases.
                   Potato Res. 16: 234-243.

    Graham D.C., Hamilton, G.A., Quinn, C.E. and Ruthven, A.D. Control
    (1975)         of potato gangrene by fumigation of tubers with
                   2-aminobutane after periods of storage. Potato Res.
                   18: 410-415.

    Quinn, C.E., Harper, P.C. and Graham, D.C. Effect of fumigation of
    (1976)         potato seed tubers with 2-aminobutane on plant growth
                   and yield. Potato Res. 19: 147-155.

    Rice, B. Res. Rep. Pl. Sci. Crop Husb. An Foras Taluntais (The
    (1973)         Agricultural Institute) Dublin pp. 80.

    See Also:
       Toxicological Abbreviations
       Butylamine, sec- (WHO Pesticide Residues Series 5)
       Butylamine, sec- (Pesticide residues in food: 1977 evaluations)
       Butylamine, sec- (Pesticide residues in food: 1979 evaluations)
       Butylamine, sec- (Pesticide residues in food: 1980 evaluations)
       Butylamine, sec- (Pesticide residues in food: 1981 evaluations)