Report on experiments with methyl bromide as a fumigant for stored tobacco

MISSING IMAGE

Material Information

Title:
Report on experiments with methyl bromide as a fumigant for stored tobacco
Physical Description:
10 p. : ; 27 cm.
Language:
English
Creator:
White, W. H ( William Henry ), 1892-1951
United States -- Bureau of Entomology and Plant Quarantine
Publisher:
United States Department of Agriculture, Agricultural Research Administration, Bureau of Entomology and Plant Quarantine
Place of Publication:
Washington, D.C
Publication Date:

Subjects

Subjects / Keywords:
Bromomethane -- Testing   ( lcsh )
Tobacco -- Fumigation   ( lcsh )
Genre:
federal government publication   ( marcgt )
non-fiction   ( marcgt )

Notes

General Note:
Caption title.
General Note:
"E-753."
General Note:
"August 1948."
Statement of Responsibility:
by W.H. White.

Record Information

Source Institution:
University of Florida
Rights Management:
All applicable rights reserved by the source institution and holding location.
Resource Identifier:
aleph - 030293013
oclc - 780085006
System ID:
AA00025143:00001

Full Text



August 1948 E-753

United States Department of Agriculture
Agricultural Research Administration
Bureau of Entomology and Plant Quarantine



REPORT ON EXPERIMENTS WITH
METHYL BROMIDE AS A FUMIGANT FOR STORED TOBACCO

By W. H. White
Division of Truck Crop and Garden Insect Investigations l


The experimental work on methyl bromide as a fumigant for control
of the cigarette beetle (Lasioderma serricorne (F.)) and the tobacco
moth (Ephestia elutella (Hbn.)) in stored tobacco is reported herein.
This report does not constitute a recommendation of this material as a
fumigant for tobacco.

Tobacco was fumigated with methyl bromide both in vacuum chambers
and under atmospheric pressures. Most of the studies were conducted at
Richmond and Newport News, Va., during 1939-41. Data were obtained on
the fumigation of a cigar factory at Selma, Ala., in April 1948.

Vacuum Fumigation

Laboratory tests.--In an effort to determine the relative effec-
tiveness of methyl bromide and hydrogen cyanide at reduced pressure, a
series of replicated tests were conducted in an experimental vacuum
chamber, 33 cubic feet in sizeaa described by Brubaker and Reed. J
In each test or fumigation, three bales of imported Turkish tobacco were
used, one of which was not fumigated, but was held as a check. These
bales weighed approximately 140 pounds each. Conditions in all tests
were as uniform as possible. Tobacco and air temperatures were constant
at approximately 70 F., and the moisture content of the tobacco was
about 13 percent. A perforated, hollow-steel test spike containing
large, nearly mature cigarette beetle larvae were driven into each bale.
These larvae had been reared under laboratory conditions and were selec-
ted at random. Each spike held the larvae at depths of 1, 3, 5, 7, and
9 inches in the tobacco, with 25 larvae being used at each depth. Fumi-
gation was performed with a vacuum of 28 to 29 inches as recorded on a
standard mercury gauge. After fumigation the chamber was air washed
twice to remove as much gas as possible, and the tobacco then removed
from the chamber. The test insects were allowed to remain in the tobacco
for 72 hours after fumigation. They were then removed to glass-covered

I/This report was prepared by J. N. Tenhet. The work was performed
by J. P. Vynzant (resigned Sept. 15, 1940), P. K. Harrison, R. W. Bru-
baker, and J. N. Tenhet. Prior to 1942 the work was under the direct
supervision of W. D. Reed (resigned June 13, 1946).
_/Brubaker, R. W, and W. D. Reed. 1943. lFumigation of tobacco at
reduced pressures. Jour. Econ. Ent. 36s 200-303.


SEP 9- ,.






-2-


dishes for a 7-day period of observation for mortality. Each fumigant
was tested at dosages of from 1 to 4 pounds per 1,000 cubio feet, at an
exposure of 3 hours, and every test was replicated 6 times or more.

Results of these tests are presented in table 1. Under the condi-
tions of this experiment it can be seen that either 2 or 3 pounds per
1,000 cubic feet of methyl bromide gave 100 percent mortality of the
test insects, and that 4 pounds of hydrogen cyanide were required to
produce the same results.

Commercial experiments: To obtain information on the behavior of
methyl bromide under commercial conditions, a large-scale experiment
was conducted in 1940. In a series of replicated tests at moderately
low temperatures, Turkish tobacco was fumigated at Richmond and at
Newport News, Va.

In the first series of tests at Richmond, bales of Turkish tobacco
were fumigated in commercial vacuum chambers of 1,028 cubic feet capacity,
each. The chambers were filled to capacity with bales of tobacco, evacu-
ated to approximately 29 inches on a standard mercury gauge, and a dos-
age of 4.62 pounds of fumigant per 1,000 cubic feet was introduced.
After an exposure of 4 hours the chambers were air washed twice and the
tobacco was then removed. As in the laboratory tests insects were in-
serted into the tobacco by means of perforated steel test spikes and
allowed to remain in the tobacco for 72 hours after fumigation. Mortal-
ity was recorded at the end of 7 days after fumigation. During the course
of the tests tobacco temperatures ranged from 30 to 43 F.

In this first series of tests, 6 replicates of each test were como
pleted with hydrogen cyanide and 4 with methyl bromide. A total of
3,168 eggs of the tobacco moth, 1,568 eggs of the cigarette beetle, 90
larvae of the tobacco moth, 749 larvae of the cigarette beetle, and 191 '
.cigarette beetle pupae were exposed to hydrogen cyanide. A total of
2,342 tobacco moths eggs, 715 cigarette beetle eggs, 60 tobacco moth
larvae, 495 cigarette beetle larvae, and 193 cigarette beetle pupae were
exposed to methyl bromide.

Mortality of all stages was 100 percent for both insects, except
that in two tests with methyl bromide some eggs of the tobacco moth sur-
vived. .

The second series of tests were conducted at Newport News at
slightly higher temperatures. In this experiment the vacuum chambers
of 3,026 cubic feet capacity, each, were also evacuated to a pressure of
approximately 29 inches on a standard mercury gauge. The dosage of
fumigant was 5 pounds per 1,000 cubic feet and the exposure period was
4 hours. Following fumigation the chambers were air washed twice before
removing the tobacco. Mortality data on test insects were obtained by
the test-spike method previously described. During this experiment
tobacco temperatures ranged from 57 to. 0 F. .A total of 5 replica-
tions or separate fumigations were completed for both methyl bromide
and hydrogen cyanide. A total of 832,000 pounds of tobacco were fumi-
gated with methyl bromide and 778,000 pounds fumigated with hydrogen
cyanide. A total of 2,250 eggs and 1,672 lirvae of the cigarette beetle
and 224 larvae of the tobacco moth were exposed.







-3-


Table l.--Mortality of 50 large cigarette beetle larvae exposed at
indicated depths in bales of Turkish tobacco to fumigation at reduced
pressure for 3 hours at 70 F. Richmond, Va,, 1941.

Fumig ibs l, sw t
per 1,000 :Percent mortality in tobacco at depths of:
ou. ft. a 1 in. t 3 in. : 5 in. : 7 in. j 9 in. : Average
Fumigation with methyl bromide


1






Av.
2 (Av. 6 tests)
3 (Av. 6 tests)
4 (Av. 6 tests)
Check
(Av. 25 tests)_/


96
86
26
96
100
6
76
73.1
100
100
100

0.6


100
100
16
100
100
86
98
86.0
100
100
100

2.3


100
100
62
100
100
78
100
91.4
100
100
100


2.3


100 100
100 ,10
56 56
100 100
100 100
96 90
96 94
92.6 91.4
100 100
100 100
100 100


0.6


1.7


Fumigation with
100 100
100 100
100 98
98 94
100 100
100 100
99.7 98.7


100
100
100
100
100
100
100
100
100
100
100
100
100
100


100


Check(Av. 24 tests)&/ 1.3


100
100
100
100
100
100
100
100
100
100
100
100
100
100


100

1.7


hydrogen cyanide


96
100
92
86
100
100
95.7
100
100
100
100
100
98
99.7
100
100
100
100
100
98
99.7


100

1.5


92
98
90
88
100
100
94.7
98
100
100
100
98
100
99.6
98
100
100
100
100
100
99.7


100


10


l_/ Only 25 larvae used at each depth in each test.


99.2
97.2
44.4
99.2
100
71.2
93.2
86.9
100
100
100

1.5


Av.


Av.







Av.


Av.


98
96
98
96
98
98
97
100
100
100
100
100
100
100
100
100
ioo
IOO
100
100
100
100


100


97.2
97.8
95.6
92.8
99.6
98.6
97.2
99.6
100
100
100
99.6
99.6
99.7
99.6
100
100
100
100
99.6
99.9


100


2.2


1.5






-4-


bMortality of test insects was 100 percent at all depths in the
tobacco in all tests with both gases.

Following fumigation, the tobacco used in this experiment was
stored in separate warehouses -- that fumigated with methyl bromide in
warehouse 22-A, and that fumigated with hydrogen cyanide in warehouse
22-T. The weekly insect-trap catch from the two warehouses is shown in
table 2. The insect population was appreciably higher in the warehouse
containing tobacco fumigated with methyl bromide. However, the tobacco
moth passes the winter outside of the mass of tobacco; hence, perhaps
the large emergence of moths in warehouse 22-A could be attributed in
part, at least, to a heavier population in this warehouse the preceding
year.

Table 2.--Weekly catches in suction light traps in warehouses containing
tobacco fumigated in March. Newport News, Va., 1941.



Period : Warehouse 22-A, tobacco : Warehouse 22-T* tobacco
ending : fumigated with methyl bromide z fumigated with HCN

STobacco moths : Cigarette beetles.Tobacco moths Cigarette beetles

May 9 2 0 0 0
16" 3 0 2 0
23 44 0 18 0
31 300 0 50 0
June 6 100 0 40 0
13 48 1 29 3
20 28 4 22 0
27 19 0 12 I
July 5 10 5 8 0
11 2 2 3 2
18 2 5 4 5
25 5 3 1 1
Aug. 1 26 5 3 1
8 44 2 30 0
15 68 1 29 1
22 150 4 30 0
29 71 0 9 1
Sept. 5 51 16 20 6
12 59 8 7 1
19 5 5 0 1
26 49 6 4 10
Oct. 3 110 0 9 1
10 100 0 13 0
17 96 2 8 0
24 43 1 12 0

Total 1,433 68 343 34

Weekly
average 57 2.7 13.7 1.4







-5-


Atmospheric Fumigation

Warehouse fumigation.--Four tobacco warehouses were fumigated at
Richmond in 1941. Two of them contained hogsheads of cigarette tobacco
of the flue-cured type, and two contained bales of Turkish tobacco. One
warehouse of each type of tobacco was fumigated with methyl bromide and
the other with hydrogen cyanide. The warehouses were comparable in every
way, except that one was somewhat smaller. Each of three of the ware-
houses were approximately 239,000 cubic feet in size, while the fourth
was only 177,000 cubic feet. Each of the larger storage contained about
1 .500,000 pounds of tobacco, while the smaller contained about 1,100,000
pounds. Prior to the fumigation on September ll, no insect control meaS-
ures had been practiced in these buildings in 1941, except the operation
of suction light traps. The tests were uniform in respect to the sealing
of the buildings and the introduction of the fumigants. The dosage of
fumigant used was 12 ounces per 1,000 cubic feet, with an exposure of 72
hours. Test lots of eggs and adults of the cigarette beetle and the
tobacco moth were exposed in the air space of each warehouse at three
elevations from the floor, and lots of cigarette beetle larvae were
placed in the tobacco in each warehouse (by means of test spikes) at
depths of 1, 3, and 5 inches. At the beginning of the experiment the air
temperature was 76 F. Unfortunately, bad weather developed and the
temperature dropped to 490 F. for two nights of the 3-day period.

Mortality of eggs and adults of both kinds of insects exposed in the
air space was 100 percent in all four warehouses. Mortality of the
cigarette beetle larvae in tobacco is given in table 3. The penetration
of methyl bromide was definitely superior to that of hydrogen cyanide.
In one warehouse fumigated with hydrogen cyanide the sealing of the door
was broken by the wind, permitting loss of an unknown amount of gas. This loss
would in part account for the comparatively low mortality of test insects
in the tobacco in this building.

Table 3.--Percent mortality of 150 cigarette beetle larvae per test in
tobacco fumigated at atmospheric pressure with methyl bromide and
hydrogen cyanide. Richmond, Va., 1941.



S: Percent mortality in tobacco
Fumigant : Type of at depths of
: tobacco :
c 1i inch : 3 inches 1 5 inches

Methyl bromide Turkish 100 98.7 99,3
Flue-cured 100 100 99.9

Hydrogen cyanide Turkish i/ 93.3 54.7 47.3
Flue-cured 100 98.7 65.3

None Flue-cured 23.3 28,0 32,7

l/ Wind broke the sealing of the door on the warehouse and ; r
affected the results.






-6-


Weekly trap catches of cigarette beetles and tobacco moths in the
fumigated warehouses are shown in table 4.. The relative insect popula-
tions in the four warehouses after fumigation indicate that there was
little difference in the control given by the two insecticides, although
the control of the tobacco moth was slightly better with methyl bromide
than with hydrogen cyanide.

Cigar factory fumigation.-A cigar factory at Selma, Ala., was fumi-
gated in April 1948. This two-story brick building was over 900,000 cubic
feet in size, and held a considerable stock of cigars, as well as filler,
binder, and wrapper tobacco, A dosage of 11 pounds of methyl bromide per
1,000 cubic feet was used with an exposure of 44 hours. The air tempera-
ture ranged from 65e to 85 F., and the weather was calm and fair.

Cigars were made with a perforated capsule containing 25 cigarette
beetle larvae rolled within the tobacco. Each of these cigars was placed
at random in a box of 50 cigars in a rack of such boxes. Twenty-five
cigarette beetle larvae were also placed in each compartment of test
spikes that were inserted into bales of wrapper, binder, and filler
tobacco, and into a bag and pile of loose, 'strip-filler tobacco#

Mortality of the test insects was high, as shown in table 5. Penetra-
tion of the gas was excellent. The larvae in cigars were all killed, except
in a sin-le instance where 3 survived out of a total of 275 exposed. In
bales of Connecticut Broadleaf, mortality was 100 percent at all depths to
9 inches, and in bales of Wisconsin binder, at depths of 7 inches or less,
but there was some survival at 9 inches. In bales of Florida wrapper, mor-
tality was 100 percent to a depth of 3 inches, and 76 percent at 5 inches;
at greater depths than 5 inches kills were light.

No effect of the fumigant upon the tobaccos was noted, and no odor of
gas could be detected after 20 hours of aeration.









-7-


4,
.4-)


'C






0



14.
,0
ra


4>
W
El

4.)
4,




taD
"9-I


hfl
*-4
Iir

4-)


0

0



woo





-4







0

54.
4-) 1a

















010
r-l
aS
(3


a i
w

4-1
0
9-4


0















4.'
0

0
0
































0
E4

















o
4,

0
09l
0










-* ** We












43



0
0
0

0
H-


-*f 4 C


n) OOOOtOCw 0r-4O
CMl V-4 r-I


C f4 m0 0c
r-4 0
.-4


CM Pt 1O W 0
10to CM


0










0


0
taD
0




0









.4.4
h0
































4
01

0







0)
.i-4
El
0:
14






,0



4.)


r-4
r-4 CO

C4
0

4-


0

&0
*o
'C


oS


I-.


"O 0l- "< mO~ CM0
C%2 CM4 to e-







C000000tC41









r-4 r-l1414


0 )010u0

r-4 C to


w t- r-I4 U)
04 rf r-I


wMO<03QOtw"
r-CN r4 04Mt') r-4


t-1o 1r


CO t'- 0 t'-O m Nt- v^
to wO MO 41 4' ) r-4 r-q
r-4 >-1 qdf









-8-


0-P
hoa
a! 0
0 N
P, o
o4 P
-0 of 0


fr,

0
0 LO
"4 OD

m
4-)
0 1







4-)
0







4-p4

CH
4 0







o


04
4,-
-PoO




















0
40~
d
or













r- 0
.c
4-)























4- 4)
,.40





















o



o
(6 o
































to
wly
4-1
410





























E-4
,-.
0 0)
00






'-- 0
.0
4)43



0 0
bD0
.r4 5


0,~



o) S


o 4
6 -
1H 0^
'5.

0 t.
'-. 1.a
0PA ol
fcd
Hj


U,
CO
0
o
'-4



o t- LO0 o ODo
OOtO)OOI







0 00 CO 0 0 1
o ooo











84r-4 r-4 r-i
.-1




0oo0 0 I



0 0 (0 0 0 1
r-4 r-l 0-i r-4




0 0 0 00 1
000001











r-4 r-4 r1 9-4 r-4
O00tO0


















000001
000001



0- r- 00- -
000001


0







[14
4-.
0


*I4








0
0
41-









0
E4













00
3-4

4)>
0
H-
0. 04


0 0 0 LO 1O 0
LO 1O U) CM) CQ U)
04 CM C r-l r-li ri-









0



0I 0
0 4)
41 00*r

-S.0 03
--- 'N m< P4
) 3'1 0 af 45


r4l"' ,0 (Dt bO 0
%- -' hbf' &4
oj^ Cd as n r
0 0 1-4 0-. P4 a.'
m a P4 d o
.4.l P454 -

3 H *Hs r
01 D (I r0 r"14

4> C.) 0 1r) D wS
0 "4 &1
4 46
(o 1.4 ho
0 "Jl r-4 4,> .^
0 st PO to 0


I I I
I I i






I I I
I I I

















I I I00
I I I






I I I
I I I







I I I
I I I








t- LOU)




0)
41)









o
0

0


as r-I a)
C-4 r-i .





0
Lo o to N
0 '0
0H 0+
01- -H 4)'


10410w




..0 3,0


(0




0 1
r-4 0
0
00



0)54

o
0 4-4





145

4-)0
0 0











414)

04
04-0
0










<<- 0
4 -1
D40

4)

0 tl

-i 0


0
0











041Q
0A 0
0) tH







W 4)
0 -4








4-)
03
4$ -H









1 (al
bo 0

o-I

0

4)0
0
1-4 0
CM4>

05-4

~41

'o
"-4 (

0'd

t0
or tl
0 1







>1-


4.4 0-4
0 93
0
to to

0
0
P 43


4-4
0

4)
Cd
to *
0 $1
10 as

0



0 -P

14 0




t0


0
o r






40 a



( 0




4.40
o









CH

4-)


P4 0
0 0


D o


4
5-4 0
04




co4 )




0 0

4z


4-)
(00'

-I-.' I
to >












E4
C33
s6
N8


*o
0
u)




4* 09












,.
0
41
r-i
P4

0
54
0


--as.






.-9-


Effect of Methyl Bromide on
"Sweating" of Tobacco

Fumigation has been suspected of adversely affecting the "sweating"
or fermentation of tobacco. In 1940 and 1941 large :,..ntities of Turkish
and flue-cured tobacco were fimigated with methyl bromide in vacuum and
at atmospheric pressure. Careful records were made as to the sweating
of this tobacco. In all instances the tobacco fumigat.=d with methyl
bromide sweated normally and no injurious effects of ewn? 1.ind were noted.

Reports of 1ethyl Bromide Injury
to Cigar Tobaccos

In the experiments on methyl bromide fumigation no injury of any
character was noted. In 1940, however, an investigation was made of a
report of an objectionable odor in tobacco follcving fumigation. It was
found that a lot of Puerto Rican cigar tobacco (strip filler) in r-w York
had been fumigated in vacuum with methyl bromide at a dosage of 5 poc:'
per 1,000 cubic feet. A part of this tobacco had developed such an rb-
jectionable odor that it was worthless. Samples of the affected tobacco
were found to be high in bromine content, which constituted some evidence
that perhaps the odor had been caused by methyl bromide. 1Nc 3_'i:euce
could be found to eliminate the methyl bromide fumigation as the respons-
ible factor.

In the spring of 1948 another report was received, that since 1941
in the course of commercial fumigation of cigar tobaccos in Havana, Cuba,
there had been at least two instances in which tobacco fumigated with
methyl bromide developed objectionable odors.

Danger to Wafehouse Workers

CAUTION.--METHYL BROMIDE IS A POISONOUS GAS A1D SHOULD BE HANDLED ONLY
BY ESPECIALLY TRAINED OPERATORS*, However, it also may present a hazard
to workmen employed in the handling of tobacco after 'umigation. The fact
that the odor of this gas in low concentrations is not very noticeable,
increases the danger. During fumigation, tobacco absorbs a considerable
amount of the gas which is gradually released over a period of days. It
is often necessary for laborers to work in a warehouse immediately after
fumigation. Even though the concentration of poison gas may be too low
to be noticed, continued exposure for several days may result in acute
illness. For example, a crew of laborers at Winston-Salem, N. C., were
handling tobacco that had been fumigated with methyl bromide. After
several days spent in moving the bales of tobacco, two of the men developed
typical cases of acute methyl bromide poisoning. They eventually re-
covered after a prolonged period of illness.

In experiments at Newport News in 1940, data on the concentrations of
gas which would develop under certain conditions were obtained through the
cooperation of the Research Department of the Dow Che:nical Company. After
being fumigated in vacuum and air washed, bales of Turkish tobacco were
brought from the fumigation chambers &nd stored in a tobacco warehouse
100 by 100 by 18 feet. The doors and ventilation open:'n-s on two sies of





UNIVERSITY OF FLOrIDA
-.0- II II 111111111 hH1
3 1262 09239 1860
thH warehouse were screened and the other two sides were brick firewalls.
This is customary in many tobacco warehouses, but affords ra+iG&r poor
ventilation.

?efore opening the doors at 8:00 a.m., after this warehouse had been
closed overnight, 13 samples of air were taken from various points in ths
building. By chemical analysis the average concentration of methyl
bromide was found to be 37.4 parts per million. The Ya-ximum amount of
-as in any sample was 50.6 p.p.m. and the rdinimum 19 p.p.m. After the
building had been aerated the concentration of gas dr:-pped rapidly. At
8:10 a.m, the average of 3 air samples 'Iowved 29. p.p.m., and at 9:10 a. m.,
27o7 p.p.m. At 2 locations near the door the methyl bromide content of
the air had dropped rom 19 to 12,2 p.p.m. and from 30 to 17.6 pop.m.;
in the center of the warehouse the concentration had dropped only from
39k3 to 38,5 p.p.m. After thorough ventilation the hLihest concentrate
tion of methyl bromide was 16 p.p.m, and the lowest 4.5 p.p.m. The
average of 12 samples taken near the doors was 8.3 p.p.m. Under similar
-orditions, in the same warehouse, shortly after storage of 105,000
pounds of tobacco just fumigated in vacuum with methyl bromide, tests of
the air with a halide detector showed concentrations of gas ranging from
20 to 200 p.p.m.

Summary

Extensive and carefully replicated experiments have shown that
methyl bromide is an effective fumigant against the cigarette beetle,
(Lasioderma serricorne (F.)) and the tobacco moth (Ephiestia elutella (Hbn)).,

In laboratory tests at reduced pressure 2 pou-ndF of mneth+l bromide
was as effective as I pounds of hydrogen cyanide. In cor nercial-ccale
tests at reduced pressure methyl bromide was found to be aP:r-r.:'ximately
equal in effectiveness to hydrogen cyanide at the same dosage. In atmos-
-heric fuirdgation of flue-cured and of Turkish tobacco methyl bromide
was found to be more effective than hydrogen cyanide at the same dosage -
giving bettor penetration,

No injurious effects were noted to cigarette-type tobaccos from
fln-iigation with methyl bromide. F'we7er, injury to cigar tobaccos has
been reported. After fumi:t-.I.r, with :,ethyl br-mide, ci-ar tobaccos
have 'ee'n known to develop obnoxious odors. Bad odors after fumigation
with this ;oas are rare, bu-c until some explanation of this occurence can
be made or until some ro r:. for it can be found, it should be recognized
that the use of this gas on cigar tobaccos involves a risk.

For several days after fumigation with methyl bromide low concen-
tration of the jj remains in the tobaccq,Where it constitutes a health
hazard to workne.i, particularly si-,F there is little or no warning odor.