sec-BUTYLAMINE JMPR 1975
IDENTITY
Chemical name
2-amino butane
Synonyms
2-AB, 'Tutane'(R), 'Deccotane'(R), 'Frucote'(R)
Structural formula
CH3CH2CH(NH2)CH3
Empirical formula: C4H11N
Molecular weight: 73.14
B.P. 63°C
V.P. 135 mm Hg at 20°C
N20 1.394
D
d20 0.724
4
Other information on identity and properties
sec-Butylamine is a colourless liquid with an ammoniacal odour.
It has a boiling point of 63°C and a vapour pressure of 135 mm Hg at
20°C. It is miscible with water and most organic solvents.
sec-Butylamine is an organic base, forming water-soluble salts
with acids. Having an asymmetric carbon atom, it exists as optical
isomers. sec-Butylamine occurs together with a number of primary and
secondary amines as natural components of citrus peel and juice. It is
stable but corrosive to tin, aluminium and some steels.
Formulated products include not only the base but the phosphate
and carbonate salts. The hydrochloride is referred to in some early
literature but is apparently not used commercially as it corrodes
equipment. The commercial product contains 25% sec-butylamine or 26%
of the carbonate equivalent to 15.5% sec-butylamine.
The product is used alone. Compatibility with other pesticides
and adjuvants is unknown. Mixed solutions are not stable beyond three
days and concentrates or mixed solutions require protection from
direct light or extremes of temperature.
EVALUATION FOR ACCEPTABLE DAILY INTAKE
BIOCHEMICAL ASPECTS
Absorption, distribution and excretion
Studies were carried out on the distribution of sec-butylamine
in edible tissues, milk and excretory products of cows.
sec-Butylamine is apparently rapidly absorbed as evidenced by its
presence in milk at three days after feeding. The two to three day,
interval was the first assayed and the level from that time on for the
remainder of a feeding trial was constant.
Residues of sec-butylamine were found in muscle, liver, fat and
kidney in a dose relationship at 100 and 10 ppm (but not 2 ppm) levels
in the diet fed to cows for up to 28 days. The residues were found in
samples taken at 0 withdrawal time after feeding (animals were fed
diets containing sec-butylamine until sacrificed). Data on the
presence of sec-butylamine in urine and faeces suggest that it is
readily absorbed into the blood and excreted primarily in the urine
(Anonymous, 1975).
No definitive metabolism studies have been performed.
Biotransformation
Urinary samples from two dogs treated daily with 5000 ppm or 10
000 ppm were acidified and distilled. A diphenyl hydrozone was formed
which corresponded to the product formed from a reaction with methyl
ethyl ketone. Methyl ethyl ketone formed from the deamination of
sec-butylamine and appeared to be excreted. The amine nitrogen
entered the biological pool and was lost (Worth and Meyers, 1965).
TOXICOLOGICAL STUDIES
Special studies on pharmacological response
Groups of dogs were administered sec-butylamine as the
carbonate or acetate salt and data were recorded an heart rate,
respiration rate, blood pressure and with an EEG apparatus.
Intravenous administration of either the acetate or carbonate resulted
in elevated blood pressure, heart rate and respiration. Intragastric
administration of larger doses resulted in similar responses. It was
suggested that the primary acute response is similar to other amines
producing a standard sympathomimetic response (Worth and Henderson,
1965).
Special studies on reproduction
Rat
Groups of rats (20 male and 20 female rats per group) were fed
sec-butylamine acetate at levels of 0, 500 and 2500 ppm in a two
litter per generation, four generation reproduction study. The Fo
parents were allowed to bear six additional litters. The F1b, 2b and
3b litters were used as parents for the following generation and
maintained for varying periods (162-202 days after weaning their
respective litters). Reproduction indices, fertility index, gestation
index, viability index and lactation index, were normal. A reduction
of growth was noted throughout the study at the high dietary level.
Reproduction was unimpaired for any of the eight litters produced by
the Fo generation (Worth et al., 1969a,b).
Rabbit
Groups of rabbits were fed sec-butylamine phosphate in the diet
and subjected to a two generation, one litter per generation
reproduction study. Two groups of rabbits (10 males and 14 females in
the treatment group; 5 males and 10 females in the control group) were
fed for 53-54 days and the females artificially inseminated with semen
collected from two control and two treated males. The dietary levels
were 0 and 2500 ppm. The F1a were maintained for six months, divided
into groups of 6 males and 12 females, fed 2500 ppm sec-butylamine
phosphate with 5 males and 8 females fed control diets. These animals
were bred by insemination, allowed to bear young, maintained for 63
days and discarded. On postpartum day 14 and day 28 milk samples were
taken and analysed for sec-butylamine.
Mortality of several rabbits was evident at an original dose
level of 5000 ppm. After the rabbits on this level were switched to
the 2500 ppm regimen, mortality and growth of all animals was normal.
The dietary level of 2500 ppm had no effect on fertility, duration of
gestation, delivery of live progeny or lactation indices in both
generations examined. Growth of progeny in the F1 generation was
normal while it was slightly depressed in the F2. There were no
effects noted on survival of offspring in either generation. There was
a constant level of sec-butylamine found in milk at both the 14 and
28 days ranging from 20 to 77 ppm in the F1 and 19 to 84 in the F2.
(The analytical method used in the study is sufficient to detect
sec-butylamine in milk but the sensitivity is questionable as food
samples containing 2500 ppm were found to contain 1770-1820 ppm or a
recovery of 72%. The study suggests that the F1 and F2 generation were
exposed to the pesticide from parturition.) The presence of 2500 ppm
sec-butylamine in the diet had no effect on reproduction in the
rabbit (Gibson et al., 1970).
Special studies on teratogenicity
Rabbit
Groups of Dutch Belted does (10 rabbits per group) were
administered sec-butylamine acetate at a dose of 0, 75 and 150 mg/kg
daily from day 8 through day 18 of gestation. On day 28 the does were
sacrificed and half of the foetuses were examined for gross and
skeletal abnormalities. Half of the foetuses were incubated for 24
hours to assess viability after which they were examined and
discarded. Mean foetal weight appeared lower than controls and a
decreased viability of live foetuses was noted at the high dose level.
There were no differences from controls with respect to reproduction,
sex distribution of foetuses or in the number of malformations
observed (Worth et al., 1966).
Acute toxicity
LD50 Chemical
Species Route (mg/kg) form Reference
Mouse Oral 660 base Worth and Anderson, 1965
1750-2470 salt* "
iv 225 base "
Rat Oral
Newborn 350 base "
Weanling 350 base "
Adult 380 base "
Newborn 430-690 salt* "
Weanling 1270-1660 salt* "
Adult 1510-4600 salt* "
Inhalation 3.5 mg/L salt & base* "
Guinea-pig Oral 880 salt* "
Dog Oral 250 base "
250-500 salt "
Rabbit Dermal 2500 base & salt* "
*Little differences were noted in four salt forms (acetate,
phosphate, carbonate, and HCl) and the range for these is presented.
Signs of poisoning in rat included salivation for two hours
before convulsion. In rats and mice acute gastritis, excessive mucus
secretion and respiratory paralysis were noted. In dogs foamy bloody
vomitus, depression tremors and mydriasis were observed. In primary
dermal irritation studies, salts of sec-butylamine were
non-irritating while the base administered at 0.7 mi/animal was a
primary irritant.
Short-term studies
Rat
Groups of rats (10 male and 10 female rats per group) were fed
sec-butylamine acetate in the diet for three months at levels of 0,
312.5, 625, 1250, 2500 and 5000 ppm. A significant growth reduction
was noted at 5000 ppm. A dose-dependent leukopenia in both males and
females was recorded although no other effects on clinical chemistry
parameters were observed. Gross and microscopic examination of tissues
and organs showed no adverse effects of dietary sec-butylamine
(Worth et al., 1965).
Rabbit
A group of rabbits (6 males and 6 females) were treated dermally
for 20 days at a daily dose of 2 ml/kg of a 10% solution of
sec-butylamine acetate. A surfactant was present in the aqueous
solution. The skin of half of the animals was abraded prior to
initiation of the study. There was no mortality and only one animal of
the abraded group showed adverse reactions (diarrhoea) during the
study. Growth, clinical chemistry, haematology and gross and
microscopic examination of tissues and organs were normal (study
reported in summary only) (Worth et al., 1965).
Dog
Groups of mongrel dogs (2 male and 2 female dogs per group) were
administered sec-butylamine acetate by capsule for 91 days at levels
equivalent to 0, 1250, 2500 and 5000 ppm of the diet. (No indication
of whether treatment was for five or seven days/week.) No effects were
noted in this study on growth (body weight stability), haematology,
clinical chemistry or gross and microscopic examination of tissues and
organs (Worth et al., 1965).
Groups of dogs (half the dogs were purebred beagles and half were
mongrels - 4 male and 4 female dogs per group - 5 males and 3 females
were used in the low treatment level) were fed or administered
sec-butylamine acetate by capsule daily for periods of up to two
years. All animals except four at the highest dose were administered
capsules containing a dose of 0, 31, 62.5, 125 or 250 mg/kg daily. Two
male and two female dogs (of the highest dose group) were administered
the test material in the food (undefined diet reported to be
equivalent to 10 000 ppm).
Mortality (4/4) occurred in the highest group of dogs
administered sec-butylamine acetate by capsule within three weeks of
the start of the treatment. Mydriasis was reported as evident in all
treated animals (including controls an one occasion). Lacrimation
occurred at the highest treatment level accompanied by keratitis in
three of the four treated animals. Two other deaths occurred (one male
at 62.5 mg/kg and one male at 125 mg/kg) apparently not attributable
to the sec-butylamine acetate. Abnormal behaviour was not observed
in any treatment. Body weights at the termination of the study were
normal in all animals including those dogs fed 10 000 ppm in the diet.
Keratitis was observed in three of four dogs fed 10 000 ppm.
Haematology values were normal except for a reduced haemoglobin and
haematocrit value (especially in females) at 10 000 ppm. Urinalysis
and clinical chemistry values were unaffected. Gross examination of
tissues and organs indicated increased kidney weight and decreased
spleen weight in females at 10 000 ppm. Leukocyte counts were normal
as were bone marrow m/e ratios. Microscopic examinations of tissues
and organs showed no pathological conditions. A no-effect level in
this study is 125 mg acetate salt/kg body weight/day (equal to 69 mg
base/kg body weight/day) (Worth et al., 1969b).
Long term studies
Rat
Groups of rats (30 males and 30 females per group) were fed
sec-butylamine acetate in the diet for two years at dose levels of
0, 1250, 2500 and 5000 ppm. Survival of rats over the two years was
not affected by sec-butylamine acetate. Terminal body weight was
slightly reduced in males at 5000 ppm. Haematological findings
recorded at several intervals over the test period were normal.
Leukocyte count averages at the end of the study were normal but the
range of values suggested a possible leukopenia at 5000 ppm. Terminal
male kidney weight was increased while prostate and testes were
reduced. These changes were not evident in female kidney, ovary or
uterus. Gross and microscopic examinations of tissues and organs,
except where noted above, were normal. A no-effect level for this
study is 2500 ppm acetate salt equal to 686 ppm base (Worth et al.,
1969b).
OBSERVATIONS IN MAN
None.
No definitive studies have been reported. A series of letters
from industrial users of the material have been offered as suggestions
that, although occupational exposure when handling the chemical is
present, the hazard is low.
COMMENTS
sec-Butylamine, an agricultural fungicide, is absorbed in cows
through the GI tract and distributed widely in the body within two to
three days of high dietary dosing. An equilibrium level in body
tissues, milk and excrete was apparent. sec-Butylamine was noted in
milk of lactating cows and rabbits. sec-Butylamine is degraded by
oxidative deamination to methyl ethyl ketone in the dog although a
complete metabolic route has not been differentiated.
The acute toxicity of sec-butylamine is low with all salt forms
(acetate, carbonate, phosphate and hydrochloride) by several routes of
administration. General sympathomimetic signs of acute poisoning have
been noted in acute studies in rodents and dogs and in pharmacological
studies in dogs. Reproduction studies in rats and rabbits, including a
study for teratological potential, were negative. Short- and long-term
studies suggest a no-effect level of 1250 ppm of the acetate salt in
rats (equivalent to 63 mg acetate salt/kg/day) and 125 mg acetate salt
kg/day in dogs. The value of 1250 ppm in rats was based on the effect
on growth noted in the reproduction study. The no-effect levels were
recalculated and expressed as the free base. A dose-dependent
leukopenia, observed in rat, did not appear to be critical. Leukopenia
was not noted in the dog.
The carcinogenic potential of sec-butylamine was judged to be
low based on the long-term feeding study.
Data were sufficient to estimate a no-effect level and to
allocate a temporary ADI. A larger margin of safety reflected such
considerations as the probable occurrence of residues in milk and meat
and the lack of studies to define the mutagenic potential.
TOXICOLOGICAL EVALUATION
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).
Dog: 69 mg base/kg bw/day (125 mg acetate salt/kg bw/day).
ESTIMATE OF TEMPORARY ACCEPTABLE DAILY INTAKE FOR MAN
0-0.2 mg base/kg bw.
RESIDUES IN FOOD AND THEIR EVALUATION
USE PATTERN
sec-Butylamine is a fungicide particularly effective for the
control of many fruit-rotting fungi. Aqueous solutions of its salts
containing 0.5-2% amine are used as dips or sprays on harvested fruit
to prevent decay in transport or storage. The amine has been used
experimentally to fumigate harvested fruit at 100 ppm by volume for
four hours or its equivalent. In neutral aqueous solution, the salts
of the optical isomers show marked differences in fungicidal activity.
The control of Penicillium decay of oranges is due largely to the 1(-)
isomer (Eckert et al,, 1972). sec-Butylamine is non-phytotoxic to
most fruits at 10 times the recommended concentration.
Since the discovery at the University of California of the
fungicidal activity of sec-butylamine (Eckert and Kolbezen, 1962),
many workers have reported outstanding results on the control of a
variety of post-harvest diseases of many varieties of citrus. The
following are some of the more important references to the performance
of sec-butylamine in general and particularly on citrus: Eckert,
1967, 1969; Eckert and Kolbezen, 1962, 1963, 1964, 1970; Eckert et
al., 1966, 1969, 1972; Gutter, 1967; Jarrett and Gathercole, 1964;
McCornack and Brown, 1965; McCornack and Hopkins, 1965; MacLean and
Dewey, 1964; Pierson, 1966; Seberry, 1969; Seberry and Baldwin, 1968;
Vanderweyen et al., 1965.
There are a number of scientific papers indicating the
suitability of sec-butylamine for the control of post-harvest decay
of apples, pears, peaches and bananas. These include Eckert and
Kolbezen (1964), MacLean and Dewey (1964), Pierson (1966).
The use of sec-butylamine was registered in the United States
of America in 1972 (EPA, 1972, 1973; Bruner, 1974, 1975).
The recommendations for the control of Penicillium moulds of
citrus involve drenching the fruit in boxes or bins in a 1% solution
of sec-butylamine. For spray treatment on packing lines a 2%
solution of the active ingredient is recommended. To attain the best
disease control the fruit must not be rinsed with fresh water after
treatment. Fumigation treatment, though effective, is not practical
because of difficulty in maintaining an adequate concentration in the
fumigation chamber.
For the control of stem-end rot more intensive treatment is
required. This involves dipping in a 1% solution for one to five
minutes, or drenching for at least three minutes. For the control of
stem-end rot by treatment on packing lines, a much more concentrated
solution is required. Careful control of the concentration of the
dipping and spraying fluid is essential. Ph control is essential.
Although phytotoxic damage is not reported from treatments with
sec-butylamine, field injury of fruit may be more apparent after
treatment.
As far as it is known sec-butylamine has not been registered
for use on other fruits and there is no indication that it is used
commercially for fruits other than citrus.
RESIDUES RESULTING FROM SUPERVISED TRIALS
Pre-harvest treatments
There is no indication that sec-butylamine has any pre-harvest
application to crops, but Kolbezen et al. (1962a, 1969) have shown
that ripe citrus contains appreciable amounts of endogenous primary
and secondary amines including sec-butylamine. Results of a typical
analysis are shown in Table 1,
TABLE 1. Endogenous amines of Valencia oranges (mg/kg)
Amine Peel Juice
methyl 0.36 Tr
dimethyl 0.42 0.13
ethyl 5.0 1.3
isopropyl 0.082 Tr
sec-butyl 0.029 0.009
isobutyl 0.13 Tr
isoamyl Tr Tr
Citrus fruit
The following information is a summary of extensive data provided
by Elanco (1968a,b).
The mean level of sec-butylamine residues found in citrus fruit
following application concentrations of 2% and less was 5.8 mg/kg with
a range of 0.16-44 mg/kg. A dose-response correlation was observed
when sec-butylamine was applied by dip or drench methods. However,
the spray treatment did not show this relationship. The average
residues, expressed as mg/kg sec-butylamine, resulting from various
concentrations of treatment and method of application are shown below:
Dip or drench Spray
Concentration 0.5% 1.0% 2.0% 1.0% 2.0%
Residue, mg/kg 1.8 3.9 6.6 6.8 6.0
Separate analysis carried out on peel and pulp clearly indicate
that the overwhelming majority of the residues is found in the peel
portions, with the pulp showing only a trace of residue. In many
instances, the pulp is free from sec-butylamine residue at a
detectable level.
The average residue found from many trials in each type of fruit
from application concentrations of 2% and less is summarized in Table
2.
TABLE 2. sec-Butylamine residues in citrus fruit from application
concentrations <2%.
Residue, mg/kg, average
Citrus type Dip or drench Spray Dip + spray
Oranges 5.6 3.4 12.6
Grapefruit 3.7 4.9 1.6
Lemons 9.0 15.1 27.8
Tangelos 23.5 - -
Tangerine - 9.5 -
The results of analysis of 250 samples of different citrus
varieties have been grouped to show the distribution pattern of
residue levels found in the whole fruit from all treatment levels
(Table 3).
A cross-section of extensive data (Table 4, Elanco, 1968a,b)
shows the wide scatter in residue levels resulting from differing
types of treatment with different rates of application. Duration of
dipping, condition of fruit at time of dipping, nature of the pre- and
post-treatment conditions, as well as concentration of fungicide in
the dip or spray solution, all appear to affect the level of deposit.
An analysis of the data suggests that if there is an influence of the
formulation (carbonate or phosphate) on the level of residues
deposited then it is frequently overshadowed by the variability in
fruit and in packing-house practices.
The method of application must be adapted to suit packing-house
practice, variety of fruit being handled, amount of harvest injury,
likely storage requirements and marketing requirements.
Irrespective of the method of application or the amount of
sec-butylamine deposited an the whole citrus fruit it is obvious
from the data summarized in Table 5 that the amount of residue finding
its way into the pulp is negligible. Eckert (1969) indicates that this
is probably due to the impermeability of the surface cells of fruit to
amine cations. Most data indicate that the amount of sec-butylamine
reported to be found in pulp is at or about the limit of
determination, and possibly reflects the presence of endogenous
primary amines.
Kolbezen et al. (1969) give an indication of the residues
resulting from an adequate and effective fumigation (150 ppm) and from
a double-dosage fumigation (300 ppm) when sec-butylamine is
volatilized into a chamber holding various types of fruit. These data
(Table 6) show residues broadly similar to those resulting from
dipping or spraying treatments.
Other fruits
Although known to be effective against post-harvest rots of
fruits other than citrus (Eckert and Kolbezen, 1964; McLean and Dewey,
1964; Pierson, 1966), the only information available to show the
level of residues on other fruit is that given in the paper on
analytical methods by Day et al. (1966). The tabulated data
representing typical residues of sec-butylamine in fruit show
residue levels in apples ranging from 2.3 to 19.3 mg/kg (five
examples) and in peaches, 3.6 mg/kg (one example).
TABLE 3. Distribution pattern of residues of sec-butylamine on various varieties of citrus fruits
No. of samples of each variety found in range
Total samples
in each range,
Residues as% of total
(range, mg/kg) Orange Grapefruit Lemon Tangerine Tangelo Total samples analysed
0-5 62 57 13 10 - 142 56.8
5.1-10 15 17 8 4 - 44 17.6
10.1-15 7 5 7 7 - 26 10.4
15.1-20 5 2 7 3 1 18 7.2
20.1-25 - - 4 1 - 5 2.0
25.1-30 - 1 6 2 - 9 3.6
30.1-35 - - - - 1 1 0.4
35.1-40 - - - 1 - 1 0.4
>40 - - 2 1 1 4 1.6
Total samples
of each fruit
analysed 89 82 47 29 3 250
TABLE 4. sec-Butylamine residues in citrus fruit
Residue, mg/kg, after treatment with
Carbonate Phosphate
Variety Location Treatment 1% 2% 1% 2%
Oranges
Temple Florida Dip 1.49 4.86 11.0
" " " 1.37 2.68 11.2
" " " 4.15 3.38 8.13
Pineapple " " 3.20 11.6 17.0
" " " 2.98 7.2 12.4
" " " 2.41 5.78 13.9
" " Drench 5.65 6.10 5.95 6.45
" " " 3.32 3.80 2.21 3.18
Valencia " Spray 1.1-2.4
" " " 2.88 3.44 2.00 2.50
" " " 4.00 5.45 2.96 3.45
" " " 2.36 2.78 2.45 2.93
TABLE 4. (continued)
Residue, mg/kg, after treatment with
Carbonate Phosphate
Variety Location Treatment 1% 2% 1% 2%
" California Dip 0.58 1.73 0.69 0.69
" " Spray 1.73 3.76 4.00 6.32
" " " 3.32 3.06 1.03 2.16
" " Dip & spray 11.7-13.5
Grapefruit
Marsh Florida Dip 2.96 8.65
" " " 6.92 8.00
" " " 3.47 10.2
" " Drench 1.32 2.46
" " " 1.66 2.22
Ruby Red " " 2.06 4.58 2.92 2.96
Duncan " Spray 1.87 1.90 2.29 2.79
" " " 2.44 4.46 1.15 3.38
Marsh California " - 3.4-10.4
TABLE 4. (continued)
Residue, mg/kg, after treatment with
Carbonate Phosphate
Variety Location Treatment 1% 2% 1% 2%
Lemons
Eureka California Dip 1.93 1.66
" " " 0.33-24.0 1.15-16
" " Spray 0.67-44
Dip & spray 27.8
Tangerines
Orlando Florida Dip 16.2 30.8
" " Spray 3.58 5.25
Dancy " " 1.29 3.46 8.10 13.35
TABLE 5. Distribution of sec-butylamine residues within citrus fruits
Residue, mg/kg, after treatment with
1% solution 2% solution
Variety Location Treatment peel pulp whole peel pulp whole
Oranges
Valencia Florida Spray 2.34 0.42 1.34
" " " 5.30 0.23 2.48
" " " 2.05 0.39 1.19
" " " 3.02 0 1.35
Grapefruit
Marsh Florida Dip 6.43 0.09 2.96 18.1 0.31 8.65
Ruby Red " " 8.10 0 3.47 23.4 0 10.2
Marsh " Drench 2.32 0 1.32 5.14 0 2.46
" " " 1.58 0 0.82 5.50 0 2.72
" California Dip 8.7 0 4.26
" " Spray 4.18 0.09 2.02
" " " 9.53 0.16 4.59
" " Dip & spray 3.42 0 1.57
TABLE 5. (continued)
Residue, mg/kg, after treatment with
1% solution 2% solution
Variety Location Treatment peel pulp whole peel pulp whole
Lemons
Eureka California Dip 29.1 0.32 15.4
" " " 41.5 0.21 24.0 28.3 0.03 16.0
" " Spray 24.6 0 14.0
" " " 18.5 0 9.2
Tangerines
Dancy Florida Spray 17.0 0.11 3.58 23.3 0.26 5.83
" California " 1.74 0.24 0.92
These data are quite inadequate to determine an appropriate
maximum residue limit.
FATE OF RESIDUES
In stored products
Kolbezen et al. (1969) reported that residues resulting from
spray, dip or fumigation treatments are contained exclusively in the
peel and the greater part is in the flavedo. As spray or dip treatment
solutions are somewhat alkaline (Ph 8.5-9.5), there is normally a
small loss of residue during the first few days after treatment due to
volatilization. During this period, the presence of sec-butylamine
can be detected by its odour. Thereafter, the remaining residues
persist unchanged in magnitude and identity for many weeks. There is
no evidence that citrus is able to metabolize sec-butylamine in any
way. An injection of 3 mg sec-butylamine as an aqueous solution of
the sulfate salt into lemons showed no changes in quantity or chemical
nature after eight weeks (Kolbezen et al., 1969).
TABLE 6. Residues of sec-butylamine on citrus fumigated for four
hours with its vapour at two rates
ppm sec-butylamine in air
150 300
Fruit sec-butylamine, mg/kg, on whole fruit
Grapefruit 6.1 13.5
Tangerines 6.6 16.5
Lemons 13.4 29.3
Naval oranges 8.7 15.1
The same authors referred to the finding of endogenous primary
amines in citrus. Although, the amount of naturally occurring
sec-butylamine is relatively low (0.03 mg/kg), there may be from
5-7.5 mg/kg of ethylamine together with varying amounts of
methylamine and dimethylamine. The presence of these related products
give reasonable assurance that residues of sec-butylamine will
persist unchanged as there is apparently no inbuilt mechanism for
degradation of amines in citrus.
Day et al. (1968) provide data on typical residues of
sec-butylamine in fruit measured at varying intervals after
treatment. There appears to be no significant difference in the level
of residues determined 28 days after treatment compared with the
residues three days after treatment. Results obtained at intermediate
times of storage appear consistent and support the belief that the
residue is stable.
Elanco (1968a,b) reports that commercial citrus washing
procedures remove only a portion of the residual sec-butylamine from
treated citrus. The data indicate that, depending upon the vigour of
the wash and the adjuvants used, up to 50% of the residue may be
removed during washing. Relatively little of the residue is removed
when citrus is subjected to a solvent waxing process after fungicide
treatment. Application of water-based wax emulsion does not appear to
significantly lower the residual deposit of sec-butylamine,
particularly when the fruit is dried prior to waxing.
In processing
Because of the huge quantity of citrus which is processed for the
extraction of juice and other by-products, numerous studies have been
conducted to determine the level and fate of sec-butylamine residues
in the various fractions of processed citrus. Table 7 summarizes the
residue levels in various components of processed oranges, determined
during semi-commercial production over three separate seasons (Elanco,
1968a,b). The use of a five-minute dip in 7% sec-butylamine in the
1967 studies was merely an attempt to determine the effect of
excessive treatments and the fate of such residues during processing.
This amount of sec-butylamine is four to seven times the normal rate
applied to commercial citrus.
EVIDENCE OF RESIDUES IN FOOD IN COMMERCE OR AT CONSUMPTION
sec-Butylamine has not yet been widely used and therefore no
information is available on residues in food moving in commerce.
TABLE 7. Residues of sec-butylamine in various fractions of processed oranges
Residue, mg/kg, after specified treatment
Year 19651 19661 19671 19682
Fraction 1%3 2%3 1%3 2%3 7%4 1%3
Whole fruit 3.3 8.8 2.96 8.65 23.7 13-17
Juice (single strength) 0 0 0.4 0.5 0.38 0.18-0.23
Juice sacs + pulp 0 0 0.18 0.46 0.50 -
Peel residue 9.3 11.6 3.60 3.80 26.0 19.4-20.3
Peel press liquor 6.6 6.8 1.93 2.72 15.8 2.64-2.69
Molasses 25.2 27.8 13.1 24.6 82.0 22-25.7
Dried pulp 33.3 33.3 16.2 24.9 38.2 45-51
Cold pressed oil 0 0 0.46 0.50 0 0.26
1 Florida process.
2 California process.
3 Normal rate of application.
4 Excessive rate of application for experimental purposes.
METHODS OF RESIDUE ANALYSIS
Based on the method of McIntire et al. (1953) as modified by
Kolbezen et al. (1962b), Day et al. (1966, 1968) developed GLC methods
for the determination of sec-butylamine residues in fruit. By these
methods, the amine is distilled from the tissue, reacted with
1-fluoro-2,4-dinitrobenzene, and determined by gas chromatography with
an electron affinity detector. Dimethylamine interferes but can be
separated from sec-butylamine by thin-layer chromatography before
the final measurement. Of 65 pesticides studied, only ferbam, thiram
and ziram which produce dimethylamine upon hydrolysis, interfered to
any degree with the determination. The authors claim that the
recoveries fall within the 80-100% range. The limit of determination
of sec-butylamine under the conditions described is about 0.1 mg/kg.
This concentration yields a peak height of about 0.5 cm. The authors
draw attention to the fact that there are significant amounts of
endogenous amines, particularly ethylamine but also including
sec-butylamine and dimethylamine in citrus and corrections must be
made for such materials which have not come from chemical treatment.
Johnson (1968a,b) has modified the procedure of Day et al. in
order to determine sec-butylamine in citrus oil. The amines in the
oil sample are isolated by acid extraction and subsequent formation of
the dinitrobenzene derivative. The various amine derivatives are
separated by thin-layer chromatography and the sec-butylamine
content is determined by gas chromatography.
Kolbezen et al. (1969) using experience gained in the
microdetermination of amines with 2,4-dinitrofluorobenzene (Kolbezen
et al., 1962a,b) have drawn attention to important refinements which
assist in eliminating interference by endogenous amines. The limit of
determination is reported to be 0.2 mg/kg.
The United States Food and Drug Administration, in establishing a
food additive tolerance (FDA, 1973), recommend the method of Day et
al. (1968) as suitable for the determination of residues covered by
the tolerance.
The Environmental Protection Agency (EPA, 1974) published a
method developed by Elanco Products Company, and submitted with a
pesticide residue petition. When used for the determination of
sec-butylamine in milk, recoveries of 70% were obtained at 0.75
mg/kg and 85% at 1.5 mg/kg. The sensitivity is reported to be 0.02
ppm.
Kroller (1975) has reported on a method to determine
sec-butylamine residues in the peel of treated citrus involving
extraction with acid, concentration on an ion-exchange resin, reaction
with 1-fluoro-2,4-dinitrobenzene and measurement of the yellow colour
by spectrophotometry. The limit of determination is quoted as
0.05 mg/kg.
NATIONAL TOLERANCES REPORTED TO THE MEETING
Tolerances for sec-butylamine residues in raw agricultural
commodities and foods have been established as follows.
United States of America
Citrus fruit (from post-harvest
application) 30 mg/kg
Kidney of cattle 3 mg/kg
Milk and meat, fat and meat
by-products of cattle (except kidney) 0.75 mg/kg
Citrus molasses 50 mg/kg
Dried citrus pulp 50 mg/kg
APPRAISAL
sec-Butylamine has been shown to have good fungicidal and
fungistatic properties which make it suitable for application to
citrus and other fruit for controlling post-harvest rots. It is
effective for inhibiting the germination of Penicillium digitatum
spores and for controlling organisms which develop resistance to other
fungicides.
Primary amines including sec-butylamine are recognized as
natural components of citrus fruit including orange juice. Although
the fungicidal properties of sec-butylamine were originally
discovered in 1962, commercial development has been fairly recent.
Extensive data available to the Meeting demonstrate the levels of
residues resulting, in various classes of citrus fruits, from
different packing-house practices. The level of residues depends as
much on packing-house practice as on formulation or any other factor,
and it can be anticipated that commercial citrus will vary
considerably in its sec-butylamine residue content, depending upon
the need for treatment and the treatment conditions. Virtually all of
the residue is deposited in the peel, the amount appearing in the pulp
and juice being generally less than the amount of naturally occurring
primary amines which, in the case of ripe orange juice, exceeds
7 mg/kg.
Residues of sec-butylamine on citrus remain stable in storage
and withstand processing of citrus pulp and molasses. Data were
available to the Meeting to indicate the level of residues at various
steps in the processing of citrus, figures being provided for juice,
pulp, dried pulp and molasses. No information is available on the fate
in cooking citrus fruits for the production of marmalade.
Whilst sec-butylamine has also been evaluated for the control
of post-harvest rots of apples, pears, peaches and bananas, little
data were available on these aspects of its use.
The feeding of citrus wastes containing residues of
sec-butylamine can be expected to give rise to transient residues in
meat, animal tissues and milk but the results of studies known to have
been conducted were not available to the Meeting.
Several colorimetric and gas chromatographic methods suitable for
the determination of sec-butylamine residues in fruit, plant
products, animal tissues and milk are available and these have been
extensively used in the evaluation of the performance of
sec-butylamine, and in studying its fate in packing-house practice.
Several authors point to the occurrence of natural sec-butylamine in
citrus fruit and the possible interference of other primary amines in
the pulp of ripe citrus. Methods for eliminating interference from
these endogenous amines have been published.
National tolerances for sec-butylamine residues in citrus,
citrus pulp and foods of animal origin have been published.
RECOMMENDATIONS
The following maximum residue limits are recommended for
sec-butylamine in the following commodities.
Commodity Limit, mg/kg
Dried citrus pulp,
citrus molasses 50
Citrus fruits 30
Citrus juice 0.5
FURTHER WORK OR INFORMATION
REQUIRED (before 30 June 1978)
1. Fate of residues especially after processing of meat and
milk.
2. Quantitative metabolic studies in animals.
3. Information on the fate of sec-butylamine residues in
livestock when citrus pulp and citrus molasses containing
sec-butylamine are used as components in the ration of
livestock.
4. Information on the use of sec-butylamine for the control
of post-harvest rot on fruits other than citrus and on
residues resulting from such uses.
DESIRABLE
1. Mutagenicity studies with techniques currently available.
2. Clinical observations in man.
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