U.S. patent number 3,586,005 [Application Number 04/767,444] was granted by the patent office on 1971-06-22 for metal coated cigarette paper.
This patent grant is currently assigned to Reynolds Metals Company. Invention is credited to Bernard Flynn Armbrust, Jr., Alfred Lippman, Jr..
United States Patent |
3,586,005 |
Lippman, Jr. , et
al. |
June 22, 1971 |
METAL COATED CIGARETTE PAPER
Abstract
A cigarette wrapper having a coating of metal which does not
significantly reduce porosity and combustibility of the wrapper but
does significantly increase peak burning temperature of the
cigarette using the wrapper (the coating weight being preferably
about 1 microgram per square millimeter for optimum reduction of
biological activity of the smoke from a cigarette using the
wrapper). The metals which have been found suitable are the
aluminous metals, iron and tin.
Inventors: |
Lippman, Jr.; Alfred (Little
Rock, AR), Armbrust, Jr.; Bernard Flynn (Benton, AR) |
Assignee: |
Reynolds Metals Company
(Richmond, VA)
|
Family
ID: |
25079506 |
Appl.
No.: |
04/767,444 |
Filed: |
October 14, 1968 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
|
|
609384 |
Jan 16, 1967 |
|
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|
Current U.S.
Class: |
131/365 |
Current CPC
Class: |
D21H
5/16 (20130101); A24D 1/02 (20130101) |
Current International
Class: |
A24D
1/00 (20060101); A24D 1/02 (20060101); A24d
001/02 (); D21h 005/16 () |
Field of
Search: |
;131/1,9,15,17
;162/139 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Rein; Melvin D.
Parent Case Text
This application is a continuation-in-part of application Ser. No.
609,384, filed Jan. 16, 1967 now abandoned.
Claims
What we claim is:
1. A cigarette comprising a tubular wrapper of medium porosity
cigarette paper, a tobacco tiller wrapped in said wrapper, and an
aluminous metal coating on said wrapper amounting to at least 0.5
micrograms per square millimeter, and not exceeding 3 micrograms
per square millimeter, said aluminous metal coating not
substantially reducing porosity or combustibility of the wrapper,
and said cigarette having a peak temperature characteristic when
burned which is at least about 50.degree. C. to about 120.degree.
C. higher than that of a corresponding cigarette without said
coating.
2. A cigarette according to claim 1 in which the coating amounts to
at least about 0.8 micrograms per square millimeter.
3. A cigarette and the like comprising a tobacco filler capable of
burning to a porous ash, a tubular wrapper of medium porosity
combustible sheet material selected from the group consisting of
cigarette paper and thin tobacco sheet, said filler being wrapped
in said wrapper, and a metal coating on said wrapper amounting to
at least 0.5 micrograms per square millimeter, said coating not
exceeding a weight per square millimeter which would substantially
increase the difficulty of keeping the cigarette burning or permit
substantial thermal conductivity through the coating lengthwise of
the cigarette, said metal being selected from the group consisting
of an aluminous metal, iron or tin and providing a coating not
being combustible during burning of the cigarette and having the
capability when the wrapper is burned of forming with the burned
wrapper a substantially unbroken and air-impervious tubular sheath
of burned metal-coated wrapper material around the burned tobacco
ash, said sheath at least partially maintaining said ash during
smoking and having the capability of directing air during puffs
lengthwise of the cigarette through the burning zone, the cigarette
thereby having the characteristic of a peak burning temperature of
at least about 50.degree. C. to about 120.degree. C. higher than a
corresponding cigarette without said metal coating.
4. A cigarette according to claim 3, in which the metal is
iron.
5. A cigarette according to claim 3, in which the metal is tin.
6. A cigarette according to claim 1 in which the wrapper is paper
and the coating is aluminum and amounts to about 1 microgram per
square millimeter.
7. A cigarette according to claim 1 in which the wrapper is coated
only on its inner surface.
8. A cigarette and the like comprising a tubular wrapper of medium
porosity combustible sheet material selected from the group
consisting of cigarette paper and thin tobacco sheet, a tobacco
filler wrapped in said wrapper, and an aluminous metal coating on
said wrapper, said coating not significantly reducing porosity and
combustibility of the wrapper as compared to a like wrapper without
said coating, having sufficiently low thermal conductivity
lengthwise of the cigarette to avoid reducing peak temperature of
the cigarette when burned, but being present in an amount
sufficient to produce a peak temperature of about 50.degree. C. to
about 120.degree. C. above the peak temperature of a corresponding
cigarette in which said coating is omitted, the amount of said
metal coating being about 0.5 to about 3 micrograms per square
millimeter.
9. A cigarette according to claim 8 in which said amount of coating
being about 0.8 to 1.2 micrograms per square millimeter.
10. Cigarette wrapper stock comprising medium porous and
combustible material in sheet form selected from the group
consisting of cigarette paper and thin tobacco sheet and an
aluminous metal coating thereon which has substantially no effect
on porosity or combustibility of said material, and which is
present in an amount of about 0.5 to 3 micrograms per square
millimeter sufficient to produce a peak temperature of about
50.degree. C. to about 120.degree. C., when employed as a cigarette
wrapper, above the peak temperature of a corresponding cigarette
wrapper in which said coating is omitted.
11. Cigarette wrapper stock according to claim 10 in which the
coating amount is about 0.8 to about 1.2 micrograms per square
millimeter.
12. Cigarette wrapper stock according to claim 10 in which the
sheet material is paper, the coating is aluminum and the amount of
the coating is about 1 microgram per square millimeter.
13. A cigarette according to claim 3, in which the metal is
aluminum.
14. A cigarette according to claim 3, in which the wrapper is
cigarette paper.
15. A cigarette according to claim 8, in which the wrapper is
cigarette paper.
Description
BACKGROUND OF THE INVENTION
For some years there has been extensive discussion in medical and
public health circles concerning the alleged carcinogenic and other
harmful effects of cigarettes. This discussion has been
supplemented by the report of the Surgeon General of the United
States, confirming that statistical evidence tends to show a higher
incidence of throat cancer and lung cancer in the case of smokers,
and especially cigarette smokers, than is true of nonsmokers. These
carcinogenic effects are usually ascribed to the presence in
cigarette smoke of certain polycyclic aromatic hydrocarbon
compounds containing fused ring structures. Experimental studies
have indicated that carcinogenic compounds are formed during
tobacco pyrolysis and are retained in the smoke generated (by the
smoking process on cigarettes) because of incomplete combustion
during said smoking process.
The combustion of a cigarette during the smoking process is a very
complex phenomenon. The volatile components are vaporized by (1)
the radiation from the hot zone; (2) the hot gases being given off
from the burning zone; and (3) air coming through the hot zone and
being heated to cause this vaporization. These vaporized components
are subjected to pyrolysis, decomposition, reaction with other
components, and condensation in the cooler zones of the cigarette.
As the burning zone approaches the areas where previous
condensation has occurred, the condensates are again subjected to
heat along with fresh tobacco, giving rise to vaporization,
decomposition, reaction, etc., all contingent on conditions in the
immediate vicinity.
Over 500 chemical compounds have been identified in cigarette
smoke. Reduction in carcinogenicity of the smoke from cigarettes
could result from burning up more of the tar or of the carcinogens
in the smoke, or from imposing conditions whereunder less
carcinogens or more anticarcinogens are formed, or by changing the
chemical composition of the smoke to give rise to different
synergistic effects resulting in a reduction of
carcinogenicity.
SUMMARY OF THE INVENTION
In accordance with this invention, it has been found that the
higher peak burning temperature of cigarettes with more complete,
uniform combustion can be achieved by employing, in conjunction
with a conventional tobacco filler, a cigarette paper wrapper in
which the paper is coated on either or both faces thereof with a
thin layer of a metal, such as aluminous metal. The term "aluminous
metal" as used herein means aluminum and aluminum-base alloys.
The term "peak temperature" refers to the maximum burning
temperature of a cigarette achieved during the smoking process as
measured by a thermocouple (platinum --platinum plus 13 percent
rhodium) with the bead of the thermocouple placed in the center of
the transverse cross section and 30 mm. from the end of the
cigarette, which is lighted and then smoked through and beyond the
thermocouple bead. For smoking to determine tar levels and other
characteristics, the cigarette is smoked to a 25 mm. but (including
filter, if present). Puffing for smoke analysis and for temperature
measurement is carried out with puffs of 35 ml. volume and 2
seconds duration taken at 1-minute intervals on a mechanized
smoking machine until the cigarette is burned to the predetermined
length.
Close study of the action of the coating indicates that as the
metal-coated paper burns, it forms a relatively continuous and
unbroken sheath or tube around the burned and burning tobacco. This
is in contrast with the same paper and tobacco with the metal
coating omitted, in which case the paper wrapper burns to an ash of
relatively great porosity, at least partly due to many breaks in
the paper ash, thus permitting a higher proportion of air to pass
into the cigarette between the burning zone and the adjacent edge
of unburned wrapper paper, with resultant decrease in the
proportion of air drawn through the burning zone. The relatively
less broken and less porous tubular sheath of burned metal-coated
paper of the present invention opposes such passing of air into the
cigarette radially behind the burning zone. Instead, it acts as a
conduit which causes more of the air to flow, during the puff,
lengthwise through the end of the cigarette ash, so that more of
the air passes through the burning zone across its entire cross
section, thereby making more oxygen available for more complete
combustion and higher peak burning temperature during each puff.
For example, when a conventional cigarette is puffed the
temperature rises by about 20.degree. C. (comparing minimum and
peak temperatures), while a like cigarette with 1 microgram per
square millimeter aluminum coating on the wrapper has a temperature
increase of about 140.degree. C. (measured in the middle of the
cross section of the cigarette, with unbroken ash at a point 30 mm.
from the original lit end of the cigarette). On the other hand,
between puffs, the tubular sheath formed by the burned metal-coated
wrapper of the invention cuts down on airflow to the burning zone
and thus causes the cigarette of the invention to burn between
puffs at a temperature which drops to a level lower than that of a
corresponding cigarette with uncoated wrapper (e.g., about
20.degree. C. lower). This slows down wasteful burning between
puffs, thus offsetting higher rate of combustion during puffs. The
peak temperature increase effect, during puffs, seemingly is not a
catalytic effect, as aluminum coated or foil strips within the
cigarette were tried per U.S. Pat. No. 2,976,190; but no rise in
temperature resulted. In fact, they actually produced a lowering of
the temperature.
For purposes of the invention, the optimum thickness of the
aluminous metal coating is about 0.8 to about 1.2 micrograms per
square millimeter of paper surface. However, a significant increase
of peak temperature is obtainable when the average coating
thickness is in the broader range of about 0.5 to about 3
micrograms per square millimeter, accounting for an increase in
peak temperature of about 50.degree. C. to about 120.degree. C.
(compared to the peak temperature of a corresponding cigarette
without any amount of said coating).
Thus, the use of metal-coated cigarette paper within the coating
weight ranges of the invention, makes it possible, surprisingly and
unexpectedly, to raise and to control degree of combustion and peak
temperature, with a conventional tobacco filler.
It had been proposed in the prior art, for example, in U.S. Pat.
No. 2,976,190,to employ as a cigarette wrapper a strip of cigarette
paper completely coated on one side with flocculent aluminum foil,
but this involves a coating of a thickness of 0.2 mils or more,
which is not only far outside the critical weight range of the
present invention, but which, as indicated in the patent, reduces
the combustion temperature.
In U.S. Pat. No. 3,106,210, it is proposed to employ as a wrapper
for cigarettes, cigarette paper coated on one side with a thin
layer of aluminum or aluminum oxide or both, of a thickness between
about 3 and 20 millionths of an inch, and preferably 5 to 10
millionths of an inch, for strengthening the ash in order to keep
added alumina hydrate or activated alumina granules from falling
out, thereby preventing the burning of objects onto which the
alumina granules might otherwise fall. The aluminum coating is said
to be applied by vacuum deposition in a single flash at less than 1
micron pressure, which suggests that the weight of the coating of
aluminum would not be substantially over 0.3 micrograms per square
millimeter. Not more than a small temperature rise is disclosed to
be possible, due to combustion of the aluminum, contrary in both
respects to the results and findings of the present invention.
It has been further found, that the employment of cigarette paper
coatings in accordance with the invention, in addition to achieving
more complete combustion, maximizing peak temperature and improving
ash characteristics, is responsible for a reduction in the
biological activity of the tar produced by the combustion of the
paper, and of the tobacco. The optimum performance in increasing
the degree of combustion is obtained when the aluminous metal
coating has an average thickness of about 1 microgram per square
millimeter. The peak temperature increase compared to uncoated
wrapper paper drops off as the aluminous metal coating weight
decreases, so that about 0.5 micrograms per square millimeter of
aluminous metal coating is necessary to achieve the desired minimum
peak temperature increase of 50.degree. C. As the aluminous metal
coating weight is increased, the peak temperature increase rises in
some cases as much as about 120.degree. C. above the peak for the
uncoated cigarette, but does not generally continue to improve as
the aluminous metal coating weight increases above the optimum of
about 1 microgram per square millimeter. However, the aluminous
metal coating weight may be increased until such time as the net
porosity of the wrapper paper and coating drops to such a low level
that the cigarette is hard to keep lighted. As shown in column B in
Table 1, as much as about 3 micrograms per square millimeter of
aluminous metal coating have been successfully used for the purpose
of the invention. The paper may be coated on either or both sides
so that the total average weight of the aluminous metal present is
in the ranges specified above. In the case of other suitable
metals, such as iron or tin, the minimum weight is no lower than
0.5 micrograms per square millimeter to increase the peak
temperature by 50.degree. C.; e.g., a coating of about 2.5 to 3
micrograms of vacuum-deposited iron has produced a peak temperature
increase of about 60.degree. to 70.degree. C., and a coating of
about 0.5 to 0.7 micrograms per square millimeter of
vacuum-deposited tin has produced a peak temperature rise of about
50.degree. C., compared to like cigarettes with uncoated paper in
both cases.
Porosity of the unburned wrapper is defined as the time in seconds
for 50 ml. of air to pass through a 1 inch diameter circular area
of the paper being tested, under a slight negative pressure (see
Greiner test, pages 70--71 of Apr. 8, 1960 issue of Tobacco
Science). The commercially available medium porosity cigarette
paper (Ecusta Ref. 556 ) used in the Table 1 tests has a porosity
of about 22.5 seconds, for example. Coating weights of up to 3
micrograms per square millimeter do not reduce the paper porosity
substantially enough to have an adverse effect for the purposes of
the invention; for example, wrapper papers having aluminum coatings
of 1 and 1.8 micrograms per square millimeter have been found to
have porosities of 24.2 and 28.0 seconds, respectively. Cigarette
wrappers of greater and lesser porosities are commercially
available and can be used without significant effect on the coating
weight limits mentioned above. However, more coating weight could
be used to offset to some extent the effect of high level of
porosity of a particular wrapper paper.
After a cigarette has been burned the same porosity tests cannot be
applied to the ash of the wrapper that are applied to the unburned
wrapper. In order to obtain a measurement of porosity of the
wrapper and cigarette after burning, the following test has been
devised: a cigarette is mounted to be smoked at one end of a tube
connected to a manometer to read pressure drop through the
burned-out cigarette, to a vacuum source to draw air through the
tube from the burned-out cigarette, and to a flowmeter used to
establish a standard 17.5 milliliters per second flow of air
through the tube from the burned-out cigarette. The cigarette is
first smoked until all the tobacco is burned, and the ash is
supported so that it will not break or fall away. The pressure drop
is small (about 1 mm. or less of water) and hence difficult to
measure precisely. However, it has been found that for a given
cigarette there is a substantially straight line increase of peak
temperature when plotted against increasing pressure drop measured
through the burned-out cigarette. The latter pressure drop rises,
but not in a straight line relation, as wrapper paper coating
weight is increased. This further demonstrates that the tubular
sheath around the tobacco ash of the burning cigarette of the
invention is responsible for the desired increase of peak burning
temperature.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
The aluminous metal coating on the cigarette paper in the range of
about 0.5 to about 3 micrograms per square millimeter does not
detrimentally change the porosity of the unburned cigarette paper,
but does affect the burning rate and the porosity of the ash formed
therefrom. The coating does not burn, nor even ignite, but it
appears to melt or sinter without forming appreciable aluminum
oxide. It gives a strong ash and provides a substantially unbroken
continuous envelope or tube which produces the increased peak
temperature phenomenon of the invention. This is believed to be
attributable to the fact that the airflow down through the tube
provides more oxygen to the burning zone so that there is more
complete combustion of the organic matter and a higher peak
temperature during puffs. If the ash is knocked off just prior to
each puff, it is found that no substantial increase in peak
temperature above that of an ordinary cigarette is produced.
However, if in smoking a cigarette with the metal-coated paper of
the invention the ash is left in place, the peak temperature can be
increased by about 50.degree. C., up to about 120.degree. C., and
preferably up to about 100.degree. C.
The metal coated cigarette paper may be manufactured by known
methods, for example, by vacuum deposition. Regular cigarette paper
is coated in this way to provide a metal layer having the desired
thickness. This coating may be applied on either or both sides of
the paper. However, it is believed to be commercially preferable to
coat only the inside surface of the paper so that the outside will
have an uncoated appearance (and also, as suggested by another, so
that less products of combustion of the paper wrapper will be drawn
into the smoke passing through the cigarette).
The deposition of the metal on the cigarette paper may be performed
in conventional apparatus adapted for a vacuum metal coating of web
materials, and including a vacuum coating chamber, a crucible
located inside the chamber for holding molten coating metal, means
for maintaining a high vacuum and means for supplying heat to the
crucible. The paper is first degassed by a short vacuum treatment
and is then passed through the vacuum coating chamber which
contains a source of aluminum vapor, the chamber being maintained
under high vacuum, preferably well below 1 micron Hg absolute. The
source of metal vapor is molten metal in a crucible maintained at a
temperature well above the melting point of the metal being coated.
The effectiveness of the coating may depend on its quality, which
in turn is affected by many factors; e.g., degree of vacuum,
outgassing of paper, control of paper temperature and presence of
contaminants.
The effect of weight of aluminous metal coating of the cigarette
paper on peak temperature is shown in the following table:
##SPC1##
A curve drawn through the peak temperature points indicates that
the peak temperature reaches a substantially constant high level
best suited for purposes of the invention when the coating weight
is in the range of about 0.8 to 1.2 micrograms per square
millimeter. However, for purposes of reaching desirable increases
of peak temperature of about 50.degree. C. to about 120.degree. C.
above the corresponding peak temperatures of like cigarettes with
uncoated wrappers, the average weight of coating is in the range of
about 0.5 to 3 micrograms per square millimeter.
The following examples are illustrative but not limiting:
EXAMPLE 1
A cigarette having an outside diameter of 8 millimeters and a
length of 80 millimeters was prepared employing conventional
cigarette smoking tobacco (1.1 grams) as a filler and a cigarette
paper coated with a layer of aluminum having an average thickness
of 1.0 micrograms per square millimeter as a wrapper. The peak
temperature of the cigarette was 946.degree. C., compared with
842.degree. C. for a similar cigarette employing uncoated
paper.
The improvement in the type and degree of combustion is shown in
the accompanying drawings, in which FIG. 1 illustrates a cigarette
having a wrapper of aluminum coated paper in accordance with the
invention, and FIG. 2 illustrates a corresponding conventional
cigarette with the metal coating omitted.
In FIG. 1, the cigarette 1 which is being smoked, terminates in a
burning zone 2, having the approximate configuration shown. The
burning zone apex is surrounded by tobacco ash 3 and the burning
zone 2 and ash 3 are surrounded by a substantially unbroken and
relatively nonporous tubular sheath formed by the combination of
aluminum metal, which does not burn, with the ash of the cigarette
wrapper paper. During each puff the incoming air preferentially
passes lengthwise through the sheath as indicated by the arrows
shown in FIG. 1.
In FIG. 2, an ordinary cigarette 10 is being smoked, but in the
absence of an aluminous metal coating, the paper wrapper and the
tobacco burn, leaving only a porous and broken-surfaced ash 11
around the burning zone 12. The shaped combustion zone 12 is
considerably shorter than in FIG. 1. During each puff, air is drawn
as indicated generally by the arrows in FIG. 2, preferentially
radially inwardly. Much of the incoming air passes radially
inwardly through the periphery of the pyrolysis zone behind and by
passing the combustion zone 12. The net effect is that less air is
drawn through the burning zone to provide oxygen.
EXAMPLE 2
This example illustrates the effect of coating weight on peak
temperature. Samples of commercially available medium porosity
cigarette paper (Ecusta Ref. 556 ) were subjected to vacuum
deposition of aluminum to obtain average weights of deposited metal
of respectively 0.1, 0.4, 0.8, 1.0 and 1.2 micrograms per square
millimeter. cigarettes of 8 millimeters outside diameter and 80
millimeters length were prepared from each sample of coated paper,
each containing 1.1 grams of tobacco. These cigarettes were smoked
according to standard procedure and average peak temperatures
determined. The results are shown under Columan A in Table 1
above.
EXAMPLE 3
In order to compare control cigarettes with cigarettes of the
invention, both types were prepared using conventional cigarette
smoking tobacco as a filler and a commercially available medium
porosity cigarette paper (Ecusta Ref. 556 ). These cigarettes
served as controls. Cigarettes of the invention were prepared using
the same batch of cigarette smoking tobacco as above as a filler
and the same cigarette paper as above except that it had previously
been coated with a layer of aluminum having an average weight of
1.0 micrograms per square millimeter, as a wrapper. Twenty
cigarettes of each type were smoked by standard techniques
mentioned previously for measuring peak temperature and tar. The
cigarettes of both types were 7.5 millimeters in outside diameter
and 85 millimeters long, and had a standard tobacco filler content
which would amount to about 2.7 pounds per 1,000 cigarettes.
The control cigarettes had an average peak temperature of
820.degree. C. The Cambridge filter method was used to determine
both wet and dry particulate matter, to give 29.4 mg. per cigarette
wet particulate matter, and 9.1 mg. dry particulate matter, per
cigarette. The above-described cigarettes of the invention gave,
using the same procedure, 934.degree. C. average peak temperature
with 23.1 mg. per cigarette wet particulate matter, and 8.6 mg. per
cigarette dry particulate matter.
It will be understood that the principles of the invention may
readily be applied to other types of wrapper materials than
cigarette paper, such as, for example, tobacco leaves or thin
wrapper sheets made of reconstituted tobacco, which are used for
little cigars, cigarillos, and the like. Such wrappers may also be
coated with metal within the weight ranges previously
disclosed.
The following example illustrates the decrease in biological
activity obtainable with cigarettes utilizing the aluminous metal
coated paper of the present invention:
EXAMPLE 4
Cigarettes were prepared as in Example 3 so that biological
activity of the tars produced by smoking said cigarettes could be
evaluated by mouse skin painting techniques. The biological
activity of the tars was evaluated on a gram for gram basis without
regard to the amount of tar produced per cigarette according to the
following method:
Representative cigarettes from each batch were tested for weight,
air resistance and porosity of the paper, Using these data,
cigarettes of a given type were grouped according to weight and
pressure drop, and the negative pressure on the smoking machine was
adjusted to provide a puff volume of 35 ml. using constant puff
pressure of 2 second duration each minute. The smoke was collected
in condensers maintained in a dry ice-ethanol bath. The condensed
smoke (tar) was removed with acetone and the acetone solution was
concentrated to apparent dryness using reduced pressure.
The "crude tar" obtained in this manner was weighed, dissolved in
an equal volume of acetone, and then treated with eight volumes of
heptane, added slowly with mixing. The resulting two phases were
separated, the upper phase containing nonpolar components was
condensed to provide the "refined tar" to be used in subsequent
bioassays. This heptane soluble fraction possesses all the mouse
skin activity present in crude cigarette tar. The batches of
"refined tar" were prepared in quantities sufficient for a 2 -week
supply. The production rate was strictly controlled to provide
fresh tar at all times. Except during use or chemical manipulation
the "tar38 was stored at temperatures below - 20.degree. C. in low
actinic flasks.
ICR/Ha Swiss female mice in groups of 100 were used for the
bioassays beginning at 40--47 days of age. Two days prior to the
beginning of the experiment the dorsal hair was clipped using an
Oster Progeinic clipper with a size 0000 head and during the course
of the experiment the hair was clipped routinely each month. The
refined tar from each group of cigarettes was tested at 81/2
percent concentration with acetone as the solvent. Each animal was
treated with 0.25 ml. of test solution applied 10 times a week from
Monday through Friday. An additional group of mice was treated only
with acetone as negative controls for the experiment. At weekly
intervals, each mouse was examined and the number and distribution
of any grossly visible tumors was recorded on a weekly data sheet.
Animals which died were autopsied with particular attention paid to
the skin, lungs, bladder, liver and kidneys. The negative controls,
the group treated with "refined tar" from regular commercial
cigarettes, and the group treated with "refined tar" from the
product of this invention were treated for 75 weeks. Cigarettes
utilizing the Example 3 cigarettes of this invention showed a
reduction of about 38 percent in the number of mice with cancers
over those painted with tar from cigarettes using regular cigarette
paper.
None of the tested cigarettes referred to in the above examples
contained any hydrous or activated alumina, which should in any
event be kept low enough (substantially below 25 percent by weight
of the filler) in the cigarettes of the present invention to avoid
adverse effects in terms of increased biological activity.
While present preferred embodiments of the invention have been
illustrated and described, the invention is not limited thereto but
may be otherwise variously embodied within the scope of the
following claims.
* * * * *