sec-BUTYLAMINE JMPR 1977
Explanation
sec-Butylamine was evaluated for acceptable daily intake by the 1975
Joint Meeting (FAO/WHO, 1976). A temporary ADI for humans was
established to be 0.2 mg/kg body weight. Maximum residue limits were
recommended for citrus and citrus products. It was considered that the
following information was required before the ADI and maximum residue
limits could be confirmed.
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.
It was considered that information from mutagenicity studies with
techniques currently available and clinical observations in humans
were desirable.
It has been interpreted that the first requirement is a duplication of
requirement number 3 which is expressed in clearer terms.
Information in fulfillment of some of these requirements has been made
available and the following monograph addendum summarises these
studies.
RESIDUES IN FOOD AND THEIR EVALUATION
USE PATTERN
In the 1975 monograph (FAO/WHO 1976), it was indicated that
sec-butylamine had proved useful and was widely used for the
post-harvest treatment of citrus. It was stated that in addition it
had been shown to be useful for controlling post-harvest decay of
apples, pears, peaches and bananas.
In response to the request for information on the use of
sec-butylamine for the control of post-harvest rot on fruits other
than citrus, one of the principal manufacturers advised that in the
United States sec-butylamine has been cleared only for use on
citrus. The reason for this is that experimentation on other crops was
not promising enough to warrant further investigation. In the case of
apples, excellent decay control could be obtained with apples
inoculated with Penicillium expansum as long as the experiments were
conducted at room temperature. However, in refrigerated storage the
sec-butylamine treatment was not effective in preventing spoilage;
this observation discouraged further work. Also, there was some
indication of phytotoxicity to apples from some important apple
growing regions.
Notwithstanding the interest in the use of sec-butylamine on
potatoes in Europe, no interest has developed in this application in
USA and certain other countries because sec-butylamine is rather
ineffective against the two main spoilage organisms on stored potatoes
in these countries -- Fusarium dry rot and bacterial soft rot.
Much of the potato crop grown in the United Kingdom is from seed
produced by growers in Scotland where, at present the most serious
tuber diseases are gangrene, caused by the fungus Phoma exigua var.
foveata, and skin spot, caused by the fungus Oospora pustulans.
Both fungi are particularly difficult to control as they can be latent
in association with the tubers. This means that the fungus may persist
or develop extremely slowly in the seed tuber long before any visible
lesions may be found. Even at the end of the storage period, tubers
may look healthy but still be carrying the disease organisms.
At present, some potato seed tubers are dipped in organo-mercury
disinfectant solutions which control a range of pathogens and give
reasonable control of gangrene. However, there are serious
difficulties in using organo-mercury solutions.
Extensive research has shown that sec-butylamine applied by
fumigation at the rate of 200 mg/kg of potato tubers over a period of
30/40 minutes with further recirculation for 2 hours is most effective
against these diseases. The treatment has been adopted at a number of
centres in Scotland.
For general commercial use it is unlikely that more than a few farmers
would find it economically worthwhile to construct suitable fumigation
chambers, so the treatment is being carried out in official
installations, though mobile fumigation chambers are being constructed
commercially.
Residues of sec-butylamine remain on and in treated potatoes, and
cannot even be removed by boiling. Therefore the process may at
present only be used for treating seed potatoes and such potatoes must
not be subsequently sold for human consumption or fed to stock.* No
significant residues have been found in crops grown from treated seed.
* It must be expected that there will be a move to obtain clearance
for use on potatoes destined for human consumption, since it is not
practicable to sort seed potatoes from ware potatoes as they are
delivered from the fields, which is the time when treatment must be
applied.
RESIDUES RESULTING FROM SUPERVISED TRIALS
No information other than the results of further studies on citrus has
come to hand since this compound was evaluated in 1975.
FATE OF RESIDUES
In Animals
In response to the request for 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, the meeting was supplied with details of two
studies.
The objective of the first experiment (Eli Lilley, 1967) was to
determine sec-butylamine residues in faeces, blood, milk, urine,
liver, kidney, fat and muscle of lactating dairy cows fed various
amounts of sec-butylamine in their diets. Cows of varying milk
production were divided into a control group and a treated group, each
penned separately. During the base-line period of two weeks, all
animals were on control feed: a maximum of 15 lbs twice daily of a
dairy lactation ration, with concentrate hand-fed to each cow, 2 1/2
lbs twice daily at milking time. Milking and feeding were on a 12 hour
schedule. Samples from individual cows were analysed and reported
separately. The treated cows were fed a ration to which was added
sec-butylamine as the phosphate at levels of 100, 20, 10, 5, and 2
ppm. Twenty-four hour composite milk samples, samples of edible tissue
(immediately after withdrawal) from the 100 and 2 ppm cows and grab
samples of urine, blood and faeces from the 100 and 10 ppm cows were
assayed for sec-butylamine.
The 100 ppm feeding level is 5-10 times the level that would be
expected in a dairy ration containing citrus by-products.
The sec-butylamine was determined as the dinitrophenyl derivitive by
gas-chromatography using electron affinity detection, with a limit of
determination of 0.003-0.01 mg/kg, depending upon the substrate.
Endogenous sec-butylamine was found to be present in most samples
from control cows: it was identified in milk by infra-red spectroscopy
and gas chromatography.
The volatile amines in the milk sample were isolated by steam
distillation and subsequent formation of the dinitrophenyl
derivatives, which were separated by thin-layer chromatography. The
dinitrophenyl derivative of C4 amines were eluted from the absorbent
and the sec-butylamine content determined by gas chromatography. The
specificity and sensitivity of this procedure were described by Day et
al. (1966). The large quantity of volatile amines in milk necessitated
extensive isolation and purification procedures involving 10 separate
operations. Table 1 indicates the level of sec-butylamine found in
the milk of animals receiving 100 ppm in the total diet (equivalent to
1.6 g of sec-butylamine per head per day) as compared with the milk
of control animals.
A dose-response relationship was observed between the amount of
sec-butylamine fed and the amount found in milk, blood, urine,
faeces, kidney and liver. The sec-butylamine appeared to be readily
absorbed and excreted in the milk and urine. It is estimated that less
than 1% of the amount fed was found in the milk.
The composite range and range of individual results for each type of
sample are shown in Table 2.
Although the amount of sec-butylamine in lean meat was not
significantly higher in the dosed than in the control animals, there
were significant amounts of sec-butylamine in kidneys at all feeding
levels with a maximum of 2-6 mg/kg at 100 ppm, and in liver at the 100
and 10 ppm feeding levels. A dose-response relationship was observed
in these tissues.
The residue levels found in the blood, faeces and urine show that
sec-butylamine is readily absorbed and mainly excreted in the urine.
The second experiment (Peoples 1968) was designed to determine the
levels of sec-butylamine in milk, muscle, liver, fat and kidney of
lactating cows fed a dried citrus pulp ration made from oranges which
had been treated with sec-butylamine. Seven Holstein cows were used
in this study, three as controls and four receiving a ration
containing 16 ppm sec-butylamine. The control ration was fed to all
animals during a 7 day conditioning period.
The average level of sec-butylamine found in the milk over the
treatment period for all animals was 0.33 mg/kg, and the range of
values was 0.071-0.67 mg/kg. There was no appreciable build-up of
sec-butylamine as the feeding period progressed. The average residue
at the first sampling after the feeding began was 0.35 mg/kg, 0.37
mg/kg at the mid-point and 0.42 mg/kg on the last day. Results are
shown in Table 3.
The average and range of residue levels found in each tissue and blood
are shown below.
sec-butylamine, mg/kg
Tissue Average Range
Muscle 0.050 036-0.064
Fat 0.018 0.001-0.028
Liver 0.179 0.148-0.198
Kidney 1.56 0.96-2.68
Blood 0.04 0.012-0.057
TABLE 1. sec-Butylamine feeding study in lactating
cows (Lilley, 1967)
Days on sec-butylamine in milk (mg/kg)
Treated Feed Control Animals Treated Animals*
303 305 302 650
0 0.003 0.002 0.002 0.002
0 >0.10 0.006 0.27 0.016
0 0.012 0.16 0.32 0.30
3 0.003 0.002 2.54 1.94
7 0.010 0.081 2.58 1.20
10 0.003 0.006 1.27 1.72
14 0.023 0.017 0.65 1.42
17 0.047 0.037 1.51 2.08
21 0.031 0.043 0.81 1.07
25 0.050 0.030 0.86 1.46
28 0.016 0.023 0.91 1.28
Mean 1.39 1.52
Range 0.002 - 0.16 0.7 - 2.6
* Cows received 100 ppm sec-butylamine in total diet equivalent
to 1.6 g sec-butylamine/head/day.
TABLE 2. sec-Butylamine feeding study residues in milk, tissues and fluids
of lactating cows (Lilley, 1967)
mg/kg sec-butylamine found at dietary level of
SAMPLE 0 ppm 2 ppm 5 ppm 10 ppm 20 ppm 100 ppm
Milk 0.02 0.02 0.04 0.04 0.09 1.46
0.00- 0.01- 0.01- 0.01- 0.05- 0.65-
0.32 0.04 0.07 0.15 0.11 2.58
Kidneya Mean 0.01 0.06 - 0.23 -
Range <0.01 0.05- 0.18- 0.43,
0.021b 0.10 0.30 2.61
Livera Mean 0.02 <0.01 - 0.10
Range <0.01 <0.01- - 0.04- 0.15,
0.031 0.02 0.14 0.19
Lean Mean 0.02 <0.01 - 0.03
meata Range <0.01- <0.01 0.01- 0.05,
0.05 0.01 0.06 0.07
Fata Mean <0.01 <0.01 - <0.01 -
Range 0.00- - - 0.01,
0.03 0.03
Urine Mean 0.28 - - 3.6 72
Range <0.01- 0.03- 16-
1.96 15.2 179
Blood Mean 0.06 - - 0.02 - 0.58
Range <0.01- 0.01- 0.07-
0.63 0.04 3.0
Feces Mean 0.04 - - 0.11 - 0.23
Range <0.01- - - 0.01- 0.04-
0.85 0.84 0.81
a 7 samples at 0 ppm; 4 samples at 2 ppm; 3 samples at 10 ppm; 2 samples at 100 ppm.
b One value of 0.198 omitted.
TABLE 3. Residues in milk of cows fed sec-butylamine (Peoples, 1968)
sec-butylamine, mg/kg (mean values from multiple analyses)
Days On Cow No. cow No. Cow No. Cow No.
Treated Feed* 1338 1340 1341 1342
0 0.002 0.001 0.003 0.003
3 0.33 0.45 0.29 0.32
7 0.46 0.59 0.34 0.39
10 0.44 0.57 0.26 0.38
14 0.36 0.35 0.35 0.31
17 0.42 0.47 0.26 0.34
21 0.24 0.47 0.21 0.14
24 0.35 0.38 0.31 0.16
28 0.12 0.65 0.16 0.12
31 0.54 0.45 0.35 Sample Lost
34 0.42 0.60 0.34 0.34
Average all analyses 0.32 0.49 0.28 0.24
Range all analyses 0.097-0.54 0.22-0.67 0.16-0.44 0.071-0.53
* Cows received 16 ppm sec-butylamine in the total diet.
In this experiment it was again observed that the major route of
excretion was through the urinary system. Levels up to 37.1 mg/kg were
found in the urine of treated animals and an average of 16 mg/kg was
observed during the treatment period. The mean urine level of control
animals was only 0.3 mg/kg.
APPRAISAL
Following evaluation of this compound in 1975, the Joint Meeting
considered that additional information was required before the
temporary ADI and maximum residue limits could be confirmed. Some of
this information was available to the Meeting.
In spite of early indication that sec-butylamine was effective
against a range of fungal organisms which are detrimental to a number
of fruits and vegetables, there is no indication that it is being
utilized commercially on fruits other than citrus on which there was a
complete monograph in 1975. There has been limited use on potatoes for
the control of gangrene and skin spot. Although it is known that
significant residues remain no detailed information was available.
There is no indication that these residues transfer into the tubers
that develop when the treated seed is planted, but it would be
desirable to have information on the level and fate of residues in
edible potatoes treated before being stored.
Cows receiving dried citrus pulp containing normal commercial residues
and excessive dosages of sec-butylamine excreted most of the residue
unchanged in the urine, but milk contained from 0.071 to 0.67 mg/kg of
sec-butylamine residues (mean 0.33 mg/kg). There was no tendency for
residues to accumulate as a result of repeated administration. Traces
of sec-butylamine could be detected in muscle, blood and fat of cows
slaughtered immediately at the end of a period of continuous ingestion
of sec-butylamine residues. Significant residues (1-2.7 mg/kg) were
found in kidney and lesser amounts (0.15-0.2 mg/kg) in liver.
sec-Butylamine occurs naturally at concentrations up to 0.3 mg/kg in
fresh milk and much higher in sour milk, together with significant
quantities of other endogenous amines. Extensive isolation and
purification procedures are required to separate, recover and measure
residues of sec-butylamine resulting from the ingestion of feeds
containing residues of the fungicide.
It is considered that the information received fulfils the
requirements listed in 1975 with the exception of certain specified
toxicological information.
RECOMMENDATIONS
The following temporary maximum residue limits are proposed to cover
the residues resulting from the feeding of citrus pulp and citrus
molasses containing sec-butylamine.
Commodity Limit, mg/kg
Edible offal 2 mg/kg
Milk and milk products 0.5 mg/kg
Meat 0.1 mg/kg
FURTHER WORK OR INFORMATION
Required (before 30 June 1978)
Quantitative metabolic studies in animals.
Desirable
1. Mutagenicity studies with techniques currently available.
2. Clinical observations in humans.
3. Information on the level and fate of sec-butylamine residues on
potatoes.
REFERENCES
Eli Lilly & Company (1967) -- 2-aminobutane feeding study on lactating
cows. VPR-107-741
Day, E.W., Golab, T., and Koons, J.R. (1966) Determination of
micro-quantities of C1-C4 primary and secondary amines by electron
affinity detection. Analyt. Chem., 38:1053.
FAO/WHO (1976) 1975 evaluations of some pesticide residues in food.
AGP:1975/M/13; WHO Pesticide Residue Series No. 5.
Peoples, S.A. (1968) Feeding study in lactating dairy cows using dried
citrus pulp from 2-aminobutane treated oranges. -- Report from School
of Veterinary Medicine -- University of California -- Davis.