FAO, PL:CP/15
WHO/Food Add./67.32
EVALUATION OF SOME PESTICIDE RESIDUES IN FOOD
The content of this document is the result of the deliberations of the
Joint Meeting of the FAO Working Party and the WHO Expert Committee on
Pesticide Residues, which met in Geneva, 14-21 November 1966.1
1 Report of a Joint Meeting of the FAO Working Party and the WHO
Expert Committee on Pesticide Residues, FAO Agricultural Studies, in
press; Wld Hlth Org. techn. Rep. Ser., 1967, in press
METHYL BROMIDE
IDENTITY
Synonym
Bromomethane
Formula
CH3Br
BIOLOGICAL DATA AND TOXICOLOGICAL EVALUATION
Biochemical aspects
After absorption, methyl bromide appears to be broken down by the
mammalian body, at least in part, for the level of non-volatile
bromide in the blood and tissues rises significantly. There is also
some evidence that volatile bromide, presumably unchanged methyl
bromide, is stored in tissues which are rich in lipoid material. It is
doubtful, however, whether these findings are relevant to the
consideration of the residues to be found in foodstuffs fumigated with
methyl bromide, because in this process as commercially practised no
unchanged methyl bromide persists (von Oettingen, 1946).
Acute toxicity
For rabbits the minimum acute lethal dose of methyl bromide has been
estimated at 60-65 mg per kg body-weight, when given by stomach-tube
as a solution in olive oil (Dudley et al, 1940).
100 mg/kg of methyl bromide given by stomach-tube as a solution in
olive oil proved to be fatal to rats in five to seven hours (Miller &
Haggard, 1943).
Short-term studies with fumigated foodstuff
Rat. When an unspecified number of rats was fed on a diet fumigated
with methyl bromide so as to give a residue in the diet equivalent to
5760 ppm, calculated as bromide, the animals developed diarrhoea after
three weeks and, over eight weeks in all, their weight gain was
slight, their general condition was poor and reproduction ceased
(Dudley et al., 1940).
In a further experiment extending over 16 weeks in which, again, the
number of animals was not disclosed, a residue equivalent to 1304 ppm
bromide in the diet gave rise to increased sleepiness, reduced
activity. Increased death-rate, decreased weight gain and cessation of
activity. Return to a normal diet then led to complete restoration to
health (Dudley et al., 1940).
A third experiment was carried out with groups each of 36 young white
rats, fed on a methyl bromide fumigated diet for 20 weeks. In those
receiving the diet in which the residue was equivalent to 5760 ppm
bromide adverse effects were observed - partial limb paralysis, scaly
tails, a form of xerophthalmia, loss of hair, reduced food intake,
inactivity, impaired reproduction and increased mortality. By
contrast, those animals on a diet in which the residue was equivalent
to 206 and 223 ppm bromide remained apparently healthy, although their
weight gain was slightly reduced. Finally, where the diet was a mixed
one containing fresh vegetables, cheese, peanuts, and dried fruits, in
addition to the rat pellets, all fumigated with methyl bromide at a
concentration of 3 lb per 1000 ft3 (48 g/m3) so that the residue
was equivalent to a maximum of 240 ppm calculated as bromide, no
deleterious effects were seen. In all the experiments there was no
significant histopathology (Dudley et al., 1940).
Two groups, each of 25 males and 32 females, were fed for one year on
a modified Sherman diet, previously fumigated with methyl bromide at
the rate of 2 lb and 6 lb respectively per 1000 ft3 (16 g to 48
g/m3) and having an average bromide content of 262 ppm and 637 ppm. A
group of 10 male and 15 female rats was fed the same basic diet
unfumigated but with the addition of 0.1 per cent (i.e., 1000 ppm)
sodium bromide. The control group received the unmodified diet. At the
end of 12 months none of the animals showed any evidence of adverse
effect in growth rate, organ weights and results of haematological and
histological examination (Spencer et al., 1944).
Rabbit. Groups, each of 12 rabbits, were fed for one year on diets
which had been fumigated with methyl bromide for 24 hours. When the
residue was equivalent to 3254 ppm bromide the animals developed a
progressive paralysis and urinary retention and all died within two
weeks. In the others, for which the residue was equivalent to 67 and
75 pm bromide, there were no abnormalities, apart from a slight
reduction in weight gain and some polydypsia and polyuria. Post
mortem, bronchopneumonia was common in the high dose group and changes
were found in the brain (Dudley et al., 1940).
Dog. Twenty-two beagles of both sexes, in groups of four to six
animals, were fed for one year on methyl bromide fumigated diets. The
residues of 1389, 2975 and 6097 ppm led to a bromide intake of
approximately 35, 75 and 150 mg per kg body-weight daily. Another
group of dogs was given sodium bromide in the diet at the rate of 100
mg per kg body-weight daily of bromide. Lethargy was seen only in
those animals on the high residue intake and there was occasional
salivation and diarrhoea both in this group and that on sodium
bromide. Otherwise the animals remained substantially healthy and, on
post mortem, no significant changes were found (Rosenblum et al.,
1960).
Long-term studies
No long-term studies are available.
Comments
No work has been done on the long-term oral toxicity of methyl bromide
as such. However, it is probable that by far the major part, if not
all, of the residue which persists in foodstuffs fumigated with methyl
bromide in accordance with ordinary commercial practice is in the form
of inorganic bromide. If this is so, the safety of treated products
could be assessed simply on the basis of their bromide content.
The question still remains whether the small interaction that takes
place between the fumigant and the food constituents could lead to a
significant decrease of nutritional value or to the formation of toxic
compounds. The answer to this should be provided by the feeding
studies with animals given a diet which had previously been fumigated.
These experiments have been short term and covered three species of
animals. From these it is clear that diets fumigated with methyl
bromide at the usual rates adopted commercially had no deleterious
effects on any of the animals.
TOXICOLOGICAL EVALUATION
Since nothing is known about the long-term oral toxicity of unchanged
methyl bromide no acceptable daily intake can be assigned to it as a
residue.
To judge by the work on cereal products the interaction of the
compound with the food is unlikely to have hazardous consequences.
The minimum pharmacologically effective dosage in the human adult has
been generally stated to be about 900 mg of KBr, equivalent to 600 mg
of bromide ion, daily. Assuming an adult weight of 60 kg this dosage
in man is about 10 mg/kg body-weight/day. In the light of available
toxicological information obtained from the extensive therapeutic use
in man, an acceptable daily intake for man of inorganic bromide from
all food sources can be estimated.
Estimate of acceptable daily intake for man of inorganic bromide
0-1.0 mg/kg body weight.
Further work required for unchanged methyl bromide
Chemical nature and amount of the residue in foods other than cereals.
Biochemical studies on the changes produced by methyl bromide in food.
Results of the above work should be made available not later than
three years after the publication of this report, when a re-evaluation
of this compound will be made.
Depending on the results of the above two studies, additional work
such as biochemical studies in animals, reproduction studies and
long-term toxicity studies may be required.
RESIDUES IN FOOD AND THEIR EVALUATION
Use pattern
(a) Pre-harvest treatments
Methyl bromide is very phytotoxic to growing plants, thus limiting its
pre-harvest uses. Such uses were reviewed by Page & Lubatti (1963). It
is applied to soils before planting, at low doses, to some seeds and
plants for quarantine purposes. These uses do not give rise to
significant bromide residues in foods.
(b) Post-harvest treatments
Methyl bromide is used against storage pests on cereals in many
countries. Treatment is carried out in various kinds of enclosures,
including chambers at atmospheric or reduced pressures, in warehouses,
in box cars and in barges. These are sometimes temporarily adapted for
the purpose. A few elevators are equipped for forced circulation of
the fumigant. For economic reasons, treatments are normally reserved
for specific shipments requiring remedial measures and are not carried
out as a matter of routine. Much of the methyl bromide used in
commerce contains an indicator substance (e.g. chloropicrin at two per
cent) which gives a readily perceptible warning of leakage from
fumigant containers or from stores being treated.
It is also occasionally used in admixture with "liquid fumigants". For
example, a mixture mainly containing carbon tetrachloride has high
powers of penetration down into standing grain and is sometimes
applied at the top of deep bins of standing grain. Mixtures with
ethylene dibromide are also used in a few countries, (Majumder, Muthu
& Narasinham, 1963) for the fumigation of stocks of grain in bags.
Some proprietary preparations contain three or more other components
(e.g. ethylene dichloride, ethylene dibromide, carbon tetrachloride,
carbon disulfide). Methyl bromide is also used occasionally on
processed cereals such as flour and milling by-products. It is used on
a wide range of stored products including dried fruits, pulses, nuts,
oilseeds, animal feed and other dry foodstuffs; also against insects
in clothing, furniture and timber.
Tolerances
There are no tolerances for unchanged methyl bromide. For inorganic
bromide derived from fumigation the figures in Brazil, Germany, India,
the Netherlands, Canada and USA for various cereal are 50 ppm and in
Czechoslovakia 20 ppm; in New Zealand there is a tolerance of 20 ppm
in any food.
Gibich & Petersen (1963) have determined inorganic bromide residues in
various mill fractions of fumigated and unfumigated wheat. Even with
unfumigated wheat great differences were observed in the amounts
of bromide located in different parts of the grain. The rejected
fractions (screenings and scourers) ran at 50-100 ppm approximately
whether fumigated or not, whereas flour and feed fractions gave Br
residues up to four times higher in treated, compared with untreated
samples. The type of wheat itself to some extent determines the amount
of Br found in certain fractions and there is some correlation between
bromide level and fat and protein contents. Some results obtained are
summarized in Table II.
TABLE II. TOTAL BROMIDE RESIDUE IN MILL FRACTIONS FROM TREATED WHEAT (PPM)
Mill fraction Hard red winter wheat Hard red spring wheat
Clean wheat 11.7 29.7 38.6 18.2 39.1
A grade flour 11.0 18.6 22.9 19.1 21.3
X grade flour 24.3 28.0 30.9 35.8 31.8
Y grade flour 21.0 39.5 36.6 38.3 36.9
Head shorts 10.3 60.8 79.8 22.9 96.0
Tall shorts 17.6 60.1 75.2 31.5 101.2
Bran 10.0 42.6 57.1 19.1 56.1
Germ 16.4 109.4 113.2 18.0 212.8
Dirty wheat 8.9 25.3 35.1 17.8 43.1
Screenings 51.9 55.1 60.8 17.8 71.5
Scourers 72.8 82.6 115.8 62.6 119.9
An examination of 227 grain shipments to the Netherlands from all
parts of the world in the period May 1964 to September 1965, showed
inorganic bromide residues to be present in only 14 of these. The
measurement of residues of unchanged fumigants are still being
developed but preliminary observations on the 227 shipments above
showed that residues of unchanged methyl bromide, if any, did not
exceed 0.1 ppm.
Residues resulting from supervised trials
During the exposure period some of the fumigant is sorbed1 by the
cereals or cereal products. The amount increases with the dosage used
under given circumstances and a higher moisture content usually
results in a higher residue. For example, some wheat of nine per cent
moisture content exposed at 32 g/m3 for 24 hours, gave an immediate
total bromide figure of 30 ppm whereas one at 15 per cent moisture
under the same experimental conditions gave 99 ppm (Lindgren, Gunther
& Vincent, 1962).
As shown by Lubatti & Harrison (1944), Shrader, Beshgetoor & Stenger
(1942) and Winteringham (1955) immediately after the termination of
the exposure period the residue consists partly of unchanged methyl
bromide and partly of a fixed residue resulting from some kind of
reaction with constituents of the food. The unchanged methyl bromide
disappears quite rapidly leaving a fixed residue which does not
decrease on further airing. This fixed residue behaves as inorganic
bromide. As examples of the rate of disappearance of unchanged methyl
bromide, the above-mentioned wheat, which had contained a total of 30
ppm immediately after treatment contained 19 ppm six hours later and
17 ppm after eight days and that which had contained 99 ppm
immediately gave 78 ppm and 77 ppm after these same intervals of time.
These losses are due to disappearance of unchanged methyl bromide.
Flour has been found to take up rather more than wheat when they are
exposed under identical conditions.
Winteringham (1955) showed that the fixation of the methyl bromide is
due mainly to reaction with the protein fraction mainly by methylation
of nitrogen and sulfur-containing groups with the formation of
methylated histidines, dimethyl sulfonium derivatives and lesser
amounts of methoxy and thiomethoxy derivatives. These reactions have
not been considered to be sufficient to reduce the nutritive value of
the products.
Figures for residues after commercial, or simulated commercial
treatments of wheat and flour vary widely. In one test with cornflour,
Wagner (personal communication) gives 75 ppm. In another case a figure
as high as 150 ppm for total bromides was reported in flour
immediately after fumigation and before airing had taken place. For
whole wheat, residues are rather lower than when the processed grain
such as flour is exposed. Wheat of 12 per cent moisture content
exposed under commercial conditions gave an initial total bromide
residue of 35.5 ppm which fell to 14 ppm in 24 hours (Pest Infestation
Laboratory, 1947). Wheat of 15 per cent moisture content however had a
residue of 78 ppm after 24 hours, following a fumigation under
identical conditions. These variations are probably due to the wide
1 This term is used so as to include all the gas taken up by the
exposed solid irrespective of the particular mechanism or mechanisms,
such as solution, surface retention or chemical combination, which may
be involved in any given case.
range of conditions of exposure which occur in practice, including
dosages, period of exposure, tightness of the enclosure, moisture
content of the cereals and cereal products treated and whether or not
they are turned or aired before sampling. Burns-Brown et al. (1955)
reported residues of about 50 ppm, inorganic bromide in flour after
treatments corresponding to normal commercial practice. The bromide
content of commercial flour which has not been treated with a fumigant
of any kind has been reported to fall between 2.4 and 7.7 ppm
(FAO/WHO, 1964)
Getzendaner (1966a) measured bromide residues in cocoa beans and
processing fractions resulting from the experimental fumigation of
beans with methyl bromide. Under the conditions used (five fumigations
with 1-1/2 lb methyl bromide per 100 cu. ft for 24 hours; 7-1/2 lb in
one fumigation, or 4-1/2 lb for 24 hours followed by 4-1/2 lb for 12
hours), residues of less than 50 ppm bromide were found after 24 hours
aeration. The shells of fumigated beans contained between four and six
times the amount found in a whole bean. Cocoa residues were about the
same as those found in the whole beans, but lower residues were found
in corresponding butter and nib fractions. Getzandaner & Richardson
(1966) have measured bromide residues in fruit and vegetables
experimentally fumigated with methyl bromide. Treatment at atmospheric
pressure in general gave residues of less than 25 ppm of bromide.
Yams, however, approached 30 ppm and sweet corn and peas up to 40 ppm
bromide. Typical results for other produce were: cherries 8 ppm;
peaches 3 ppm; carrots 20 ppm; oranges, grapefruit 12 ppm; cucumber 15
ppm; apples 3 ppm; cabbage 20 ppm bromide. Garlic subject to vacuum
fumigation in commercial chambers had residues of 2 to 11 ppm and
cipollini bulbs up to 48 ppm bromide. Getzandaner (1965) has also
shown that poultry meat and eggs from hens fed diets containing up to
400 ppm bromide residues contain at equilibrium no more bromide
residue than the diet.
Bär (1964) found that whilst cereals, fruit and vegetables retained
only small residues after treatment, flour and oily goods retained
much higher levels even after 48 hours aeration. Maximum levels (for
inorganic bromide) cited by the German Federal Office of Health from
rat feeding studies reported by Bär are: cereals and citrus fruit skin
50 ppm; almonds and other nuts (kernels) 40 ppm; citrus pulp 25 ppm;
cocoa beans, dried fruit 10 ppm.
The feeding of fumigated cereals to cattle may result in bromide
residues in milk. Lynn (1963) found 10-20 ppm in milk from cows fed a
diet containing 43 ppm bromide.
Residues in food moving in commerce
Duggan, Barry & Johnson (1966) reported total bromide levels of up to
200 ppm in various defined food groups in total diet studies; results
are summarized in Table I. Heywood (1966) pointed out that not all of
this bromide could be attributed to fumigants since part, at least,
occurred naturally in food.
TABLE I. BROMIDE RESIDUES IN TOTAL DIET STUDIES
Foods Bromide range ppm No. of samples
(out of 18)
Dairy produce 1.1 to 31.7 17
Meat, fish 2.3 to 35.5 16
Grain 4.4 to 111.0 17
Potatoes 1.5 to 38.0 15
Leafy vegetables 1.1 to 16.3 16
Legumes 0.9 to 17.9 14
Root vegetables 2.6 to 22.1 14
Salad fruit 1.7 to 18.9 15
Fruit 0.7 to 31.4 12
Oils, fats 1.1 to 261.0 16
Sugar, etc. 0.7 to 55.1 18
Beverages 0.9 to 17.0 10
Fate of residues
(a) In plants and animals
There is a fairly extensive literature on the activity and excretion
of inorganic bromides in animals and man. As indicated by Heywood
(1966), furthermore, small amounts of bromide occur naturally on a
fairly wide range of plant products. Residues of "apparent
organobromine compounds" reported by Gunther & Spenger (1966) were
said to be due to the extraction of inorganic bromide by organic
solvents in the presence of lecithin-type complexing agents present in
vegetable tissues. The results obtained, indicated in Table II,
probably reflect naturally occurring bromide in the various plants.
TABLE II. APPARENT ORGANOBROMINE RESIDUES IN PLANT PARTS
Plant Plant part Bromine
ppm
Atriplex lentiformis Leaves and stems 4.4
4.9
Schinus Molla Tops 1.1
Suaeda sp. Whole plants 0.3
Beets Tops 0.15
Broccoli Heads 0.13
Chard Foliage 0.2
Corn, sweet Leaves 0.15
Cucumber Seeds 9.9
Barley Whole plants 0.34
0.26
Lima beans Whole plants 0.2
Onions Whole plants 0.18
0.27
Peppers Whole plants 0.18
Radishes Whole plants 0.1
Zucchini Fruits 0.13
(b) In storage and processing
Methyl bromide disappears rapidly from whole wheat and cannot be
detected after three or four days of airing. The combined bromide does
not disappear to a significant extent during airing. When fumigated
wheat has been milled the residues found in the various milling
fractions, present at the stage as inorganic bromide, have been found
to vary: the residues in flour and other fractions for human
consumption, however, have always been appreciably lower than those in
the original wheat. For example, on one occasion wheat with 14 ppm
bromide gave flour of 5 ppm but the bran contained 13 ppm (Pest
Infestation Laboratory, 1947). Wagner (personal communication) quotes
a wheat of 26.8 ppm which yielded a flour of 12.2 ppm but the bromide
residues in the animal feed fractions had slightly increased.
Methods of residue analysis
Berck (1965) has published details of a gas chromatographic method for
the detection and measurement of some 34 fumigant vapours, including
methyl bromide. The application of this technique to the determination
of residues of unchanged methyl bromide in fumigated foods is most
desirable. The method of Napes & Shrader (1957), based on the
measurement of inorganic bromide, is in the meantime suggested as
suitable for measuring residues of total bromide in cereals after
fumigation. Working details are set out in Appendix A(4) of the
(Extract) Report of the Second Session of the FAO Working Party on
Pesticide Residues (PL/1965/12). The limit of detection is about 1
ppm.
The Joint FAO/WHO Expert Committee on Food Additives, when considering
the presence of bromide in bread due to the addition of bromate
conditioner to flour (FAO/WHO, 1964) gave estimates of acceptable
levels of treatment for flour to be consumed by man as:
Unconditional 0-20 ppm
Conditional (for special purposes) 20-75 ppm
The recommendation of 50 ppm in cereals and flour resulting from
fumigation, is in accordance with this estimate because cereals and
cereal products are treated with the fumigant to deal with specific
outbreaks and not as a routine, during milling or other manufacture,
as are flour conditioners.
RECOMMENDATION FOR TOLERANCES
On the basis of an acceptable dally intake of 1 mg/kg of inorganic
bromide, a tolerance of 50 ppm for inorganic bromide residues in
cereals and flour resulting from the use of methyl bromide and other
fumigants can be recommended. This recommendation is also consistent
with tolerances for dried eggs, processed herbs and spices at 400 ppm;
various fresh fruits at 200 ppm; citrus at 230 ppm; raisins, dates at
100 ppm and various other fruits including certain dried fruits, at
from 50 ppm to 20 ppm, which are residues which have been found after
responsible usage of the fumigant and which are as follows:
Dried eggs, spices, herbs 400
Cereals 50
Dried figs 250
Avocados 75
Dried raisins, dates 100
Dried peaches 50
Dried prunes 20
Other dried fruits 30
Citrus, strawberries 30
Other fresh fruit 20
Since no acceptable daily intake has been established for the
unchanged compound and since there appears to be no requirement for
such a tolerance in commercial practice, no tolerance is recommended
for residues of unchanged methyl bromide.
Further work or information
The measurement of residues of bromide, and of unchanged methyl
bromide (if any) resulting from the use of methyl bromide on raw
wheat, flour and other food items in commercial practice is desirable.
There would be particular interest in information on the retention of
unchanged methyl bromide in foods with a relatively high oil or fat
content. Further information on residues resulting from the use of
mixed fumigants is also desirable.
The Working Party considers that a sensitive multidetection method for
residues of unchanged fumigants (including methyl bromide) in treated
foods is now possible and the development of such a method would be a
valuable advance.
REFERENCES PERTINENT TO BIOLOGICAL DATA
Dudley, H. C., Miller, J. W., Neal, P. A. & Sayer, R. R. (1940)
Publ. Hlth Rep., 55, 2251
Miller, D. P. & Haggard, H. W. (1943) J. industr. Hyg. Toxicol.,
25, 423
von Oettingen, W. F. (1946) Nat. Inst. Hlth Bull., 185
Rosenblum, I., Stein, A. A. & Eisinger, G. (1960) Arch. environ.
Hlth, 1, 316
Spencer, H. C., Rowe, V. K., Adamo, C. M. & Irish, D. D. (1944) Food
Res., 9, 11
REFERENCES PERTINENT TO AGRICULTURAL DATA
Bär, F., (1964) Methylbromide zur Schädlingsbekämpfung
Bundesgesundheitsblatt, 7: 113
Berck, B., (1965) Determination of fumigant gases by gas
chromatography J. Agric. Food Chem. 13 (4): 373-377
Burns-Brown, W., Coppock, J. B. M., Edwards, G. H., Greer, E. K., Hay,
J. G. & Heseltine, H. K. (1955) The fumigation of flour with methyl
bromide. Chem. Ind., March 19, 1955: 324-5
Duggan, R. E., Barry, H. C. & Johnson, L. Y. (1966) Pesticide residues
in total-diet samples Science, 151 (3706): 101-104
FAO/WHO (1964) Specifications for the identity and purity of food
additives and their toxicological evaluation: emulsifiers,
stabilizers, bleaching and maturing agents. FAO Nutr. Meetings Rep.
Ser. 35: 167
FAO/WHO (1965) Evaluation of the toxicity of pesticide residues in
food. Rome FAO Meeting Report No. PL/1965/10/2, 71 p.
Getzendaner, M. E. (1965) Residues in milled wheat products resulting
from spot fumigation of milk machinery with halogenated liquid
fumigants. J. Agric. Food Chem., 13: 455-458
Getzendaner, M. E. (1966a) Bromide residues from methyl bromide
fumigation of cocoa beans and processed fractions from fumigated
beans. J. Agric. Food Chem., 14: 56-58
Getzendaner, M. E. & Richardson, H. H. (1966b) Bromide residues from
methyl-bromide fumigation of fruits and vegetables subjected to
quarantine schedules J. Agric. Food Chem., 14: 59-62
Gibich, J. & Pederson, J. R. (1963) Bromide levels in mill fractions
of unfumigated and fumigated wheat. Cereal Science Today, 8: 345-354
Gunther, F. S. & Spenger, R. E. (1966) Apparent organobromide
compounds in higher plants by neutron activation analysis. Bull.
Environ. Contam. Toxicol., 1: 121
Heywood, B. J. (1966) Pesticide residues in total diet samples:
bromine content. Science, 152 (5727): 1406
Lindgren, D. L., Gunther, F. A. & Vincent, L. E. (1962) Bromine
residues in wheat and milled wheat fractions fumigated with methyl
bromide. J. Econ. Ent., 55: 773-6
Lubatti, O. F. & Harrison, A. (1944) Determination of fumigants. XVII.
Comparison of the sorption of hydrogen cyanide, ethylene oxide,
trichloro-acetonitrile and methyl bromide by wheat. J. Soc. Chem. Ind,
63: 353-9
Lynn, G. E., Shrader, S. A., Hammer, O. H. & Lassiter, C. A. (1963)
Occurrence of bromide in the milk of cows fed sodium bromide and grain
fumigated with methyl bromide. J. Agric. Food Chem., 11: 87-91
Majumder, S. K., Muthu, M. & Narasinham, K. S. (1963) Behaviour of
ethylene dibromide methyl bromide and their mixtures. I: in columns of
grains and milled materials. Food Technol., 17; 106-111
Mapes, D. A. & Shrader, S. A. (1957) Determination of total and
inorganic bromide residues in fumigated products. J. Ass. Offic. Agr.
Chem., 40: 189-96
Page, A. B. P. & Lubatti, O. F. (1963) Fumigation of insects. Annu.
Rev. Ent., 8: 239-64
Pest Infestation Laboratory. (1947) The effect on the milling and
baking quality of wheat after fumigation with methyl bromide. Slough,
Bucks. Pest Infestation Res. Rep. 11 (unpublished document)
Shrader, S. A., Beshgetoor, A. W. & Stenger, V. A. (1942)
Determination of total inorganic bromide on food fumigated with methyl
bromide. Ind. Eng. Chem. Anal. Ed. 14: 1-4
Winteringham, F. P. W. (1955) The fate of labelled insecticide
residues in food products. IV. The possible toxicological and
nutritional significance of fumigating wheat with methyl bromide. J.
Sci. Food Agr., 6: 269-74